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Osteocalcin (OC) is an abundant extracellular calcium-binding protein synthesized by osteoblasts. Although most OC is bound to hydroxyapatite mineral during bone formation, a consistent amount is released directly to circulation. Plasma OC (pOC) levels are highly sensitive to stressful stimuli that alter stress-responsive hormones, such as glucocorticoids (cortisol or corticosterone) and the catecholamines norepinephrine and epinephrine. To gain a better understanding of the apparent relationship of OC to the effects of ethanol (EtOH) and the stress responses, we compared mice that have OC (WT [OC+/+] and HET [OC+/-]) with OC null mutants (KO [OC-/-]), which have no OC in either plasma or in bone. One experiment included chronic unpredictable stress, a second was conducted in the absence of any known stressors other than EtOH, while a third imposed a more severe acute immobilization stress in addition to EtOH consumption. The data obtained confirmed significant differences in EtOH consumption in mice that previously experienced various stressful stimuli. We also determined that adrenal tyrosine-hydroxylase expression was inversely proportional to EtOH consumption and tended to be lower in KO than in WT. Data suggest that OC possesses the ability to modulate the adrenal gene expression of the catecholamine synthetic pathway. This modulation may be responsible for differences in EtOH consumption under stress.

Studies of socially housed rodents have provided significant information regarding the mechanisms of stress and of stress-related disorders. Since psychosocial stress is known to alter the functional activity of dopaminergic system, we employed amphetamine (AMP) to evaluate the involvement dopamine in mediating the behavioral consequences of psychosocial stress. Male rats housed two per cage were designated as dominant (DOM) or subdominant (Sdom) based on initial evaluations of agonistic behaviors and body weight changes. Diad-housed rats and a group of single-housed (SiH) rats were tested in an open field after injections of saline or amphetamine (0.9 or 2.7 mg/kg IP) prior to and again while diad-housing. Compared to future DOM rats, saline-injected future Sdom rats entered the open field center less frequently, spent less time in rearing behavior and groomed less. At the pre-diad test AMP treatment elevated locomotor activity of all rats, while stimulation of center entries was more marked in future DOM rats. At the diad test, AMP’s locomotor stimulant effect was evident in all experimental groups with DOM rats showing higher effects compared to Sdom and SiH rats. Amphetamine’s stimulation of center entries in DOM rats was similar to the pre-diad test, but it was diminished in Sdom rats, while stimulation of rearing behavior was most evident in diad-housed rats. The dopaminergic system modulates the psychosocial stress-induced differences in explorative and emotional behaviors. Furthermore, behavioral traits like frequency of grooming behavior and of center entries were predictive of future hierarchical status.

Psychosocial stressors are known to alter ingestion of ethanol in humans and experimental animals. We evaluated the effect of novel acute stressors on ethanol ingestion of male triad-housed rats. Based on behavioral and body weight assessments triad members were designated as dominant, subdominant or subordinate rats, housed in triads designated as aggressive or non-aggressive triads. The triad-housed, and a group of single-housed rats, were sequentially subjected to three stressors (novel open field arena, elevated plus maze, and modified resident–intruder test) at 1–2 week intervals. Ethanol intake was measured for 21-h before and after each stressor. Prior to stressor exposure, ethanol intake of the triad-housed rats was higher than that of single-housed rats. In triads overall intake of ethanol was lower in dominant compared to non-dominant rats. The modified resident–intruder test decreased ethanol intake in non-dominant rats in aggressive triads, but increased its intake in non-aggressive triads. Since in non-dominant rats this stressor also increased ethanol preference but not total fluid intake, its effect on ethanol intake was specific. In non-dominant rats ethanol intake and preference declined after the elevated plus maze stressor, without an effect on total fluid intake, but water intake was increased only in the subdominant rats. Compared to triad-housed rats, single-housed rats were more resilient to the novel stressors. It can be concluded that novel acute stressors have specific effects on ethanol intake that are dependent on the subject's psychosocial stress level.

Drug abuse researchers have noted striking similarities between behaviors elicited by Pavlovian sign-tracking procedures and prominent symptoms of drug abuse. In Pavlovian sign-tracking procedures, repeated paired presentations of a small object (conditioned stimulus, CS) with a reward (unconditioned stimulus, US) elicits a conditioned response (CR) that typically consists of approaching the CS, contacting the CS, and expressing consummatory responses at the CS. Sign-tracking CR performance is poorly controlled and exhibits spontaneous recovery and long-term retention, effects that resemble relapse. Sign-tracking resembles psychomotor activation, a syndrome of behavioral responses evoked by addictive drugs, and the effects of sign-tracking on corticosterone levels and activation of dopamine pathways resemble the neurobiological effects of abused drugs. Finally, the neurobiological profile of individuals susceptible to sign-tracking resembles the pathophysiological profile of vulnerability to drug abuse, and vulnerability to sign-tracking predicts vulnerability to impulsive responding and alcohol self-administration. Implications of sign-tracking for models of drug addiction are considered.

The present experiment evaluates the effects of intermittent exposure to a social stimulus on ethanol and water drinking in rats. Four groups of rats were arranged in a 2 × 2 factorial design with 2 levels of Social procedure (Intermittent Social vs Continuous Social) and 2 levels of sipper Liquid (Ethanol vs Water). Intermittent Social groups received 35 trials per session. Each trial consisted of the insertion of the sipper tube for 10 s followed by lifting of the guillotine door for 15 s. The guillotine door separated the experimental rat from the conspecific rat in the wire mesh cage during the 60 s inter-trial interval. The Continuous Social groups received similar procedures except that the guillotine door was raised during the entire duration of the session. For the Ethanol groups, the concentrations of ethanol in the sipper [3, 4, 6, 8, 10, 12, 14, and 16% (vol/vol)] increased across sessions, while the Water groups received 0% ethanol (water) in the sipper throughout the experiment. Both Social procedures induced more intake of ethanol than water. The Intermittent Social procedure induced more ethanol intake at the two highest ethanol concentration blocks (10–12% and 14–16%) than the Continuous Social procedure, but this effect was not observed with water. Effects of social stimulation on ethanol drinking are discussed.

We evaluated the effects of social interaction opportunity (SIO) and intermittent presentations of the ethanol sipper tube (IS) on autoshaping of ethanol drinking in nondeprived rats. Rats were assigned to one of seven groups. Two groups experienced brief IS, either paired with or randomly related to the response-independent raising of a guillotine door (D) revealing the presence of a conspecific male rat in a holding cage (SIO). Two control groups received similar training, respectively, except that the D revealed an empty cage, whereas a third control group received IS but neither D nor SIO. For two additional control groups, the ethanol sipper tube was continuously available during the session, with and without SIO, with both groups receiving intermittent D. In IS conditions, procedures with SIO induced more ethanol intake than did non-SIO procedures, indicating that SIO contributed to ethanol intake, but D procedures did not differ from non-D procedures, indicating that ethanol drinking was not related to the operation of the door. Groups that received training procedures providing for both SIO and IS showed more rapid initiation of ethanol intake and more rapid escalation of ethanol intake as the concentration of ethanol in the sipper tube conditioned stimulus was increased across sessions. Theoretical accounts, which are based on cue at response manipulandum/autoshaping, schedule-induced polydipsia, incentive sensitization, and intermittency-induced arousal, are considered.

Two experiments were designed to evaluate the effects of pairings of ethanol sipper conditioned stimulus (CS) with social opportunity unconditioned stimulus (US) on ethanol sipper CS-directed drinking in rats. In both experiments, rats were deprived of neither food nor water, and initiation of drinking of unsweetened 3% ethanol was evaluated, as were the effects of increasing the concentration of unsweetened ethanol (3–10%) across sessions. In Experiment 1, Group Paired ( n =8) received 35 trials per session wherein the ethanol sipper CS was presented for 10 s immediately prior to 15 s of social opportunity US. All rats initiated sipper CS-directed drinking of 3% ethanol. Increasing the concentration of ethanol in the sipper CS [(3%, 4%, 6%, 8%, 10% (vol./vol.)] across sessions induced escalation of daily g/kg ethanol intake. To evaluate the hypothesis that the drinking in Group Paired was due to autoshaping, Experiment 2 included a pseudoconditioning control that received sipper CS and social opportunity US randomly with respect to one another. All rats in Group Paired ( n =6) and in Group Random ( n =6) initiated sipper CS-directed drinking of 3% ethanol and daily mean g/kg ethanol intake in the two groups was comparable. Also comparable was daily g/kg ethanol intake, which increased for both groups with the availability of higher concentrations of ethanol in the sipper CS, up to a maximum of approximately 0.8 g/kg ethanol intake of 10% ethanol. Results indicate that random presentations of ethanol sipper CS and social opportunity US induced reliable initiation and escalation of ethanol intake, and close temporally contiguous presentations of CS and US did not induce still additional ethanol intake. This may indicate that autoshaping CR performance is not induced by these procedures, or that high levels of ethanol intake induced by factors related to pseudoconditioning produces a ceiling effect. Implications for ethanol drinking in humans are discussed.

Pavlovian autoshaping procedures provide for pairings of a small object conditioned stimulus (CS) with a rewarding substance unconditioned stimulus (US), resulting in the acquisition of complex sequences of CS-directed skeletal-motor responses or autoshaping conditioned responses (CRs). Autoshaping procedures induce higher post-session levels of corticosterone than in controls receiving CS and US randomly, and the enhanced post-session corticosterone levels have been attributed to the appetitive or arousal-inducing effects of autoshaping procedures. Enhanced corticosterone release can be induced by aversive stimulation or stressful situations, where it is often accompanied by higher levels of norepinephrine (NE) and serotonin (5-HT) in prefrontal cortex (PFC) but not in striatum (ST). Effects of autoshaping procedures on post-session corticosterone levels, NE contents in PFC, and 5-HT contents in PFC and ST were investigated in male Long-Evans rats. Post-session blood samples revealed higher corticosterone levels in the CS-US Paired group (n = 46) than in the CS-US Random control group (n = 21), and brain samples revealed higher levels of PFC NE and 5-HT in CS-US Paired group. Striatal 5-HT levels were unaltered by the autoshaping procedures. Autoshaping procedures provide for appetitive stimulation and induce an arousal-like state, as well as simultaneous stress-like changes in plasma corticosterone and monoamine levels in PFC. Autoshaping, therefore, may be useful for the study of endocrine and central processes associated with appetitive conditions.

Compared with the use of classic receptor ligands, antisense oligonucleotides (ASO) targeted at specific central nervous system receptors are an effective alternative in experiments designed to examine the behavioral role of such systems.The nociception/orphaninFQ (N/OFQ) system has been implicated in mediating endocrine function, feeding, stress, pain, anxiety, and the rewarding effects of drugs of abuse. The objective of the current study was to examine whether long-term ASO-induced downregulation of N/OFQ's receptor (NOP) produced changes in endocrine, anxiety, nociception and ethanol's (EtOH's) locomotor activating properties.Male Long Evans rats were implanted with osmotic mini-pumps containing ASO for the NOP receptor. ASO was chronically infused for 26 days and, during this time, multiple behavioral and physiological measurements were conducted.ASO infusion significantly reduced expression of the NOP receptor in brain, confirmed by significant reductions of OFQ-stimulated [(35)S]-GTPgammaS binding in the paraventricular nucleus, prefrontal cortex, and septum. Behavioral changes were observed in ASO-treated animals including higher body temperature, increased water intake, decreased corticosterone (CORT) levels, decreased grooming in the open field, increased tail-flick latency, shorter durations on the open arms of the elevated plus maze, and heightened locomotor activity following EtOH.These behavioral, physiological and endocrine changes are relatively consistent with previous findings with agonists and antagonists for the NOP receptor and, taken together, suggest that ASO-induced downregulation of the NOP receptor is an effective method for studying the N/OFQ system.

Social stressors, like other stressors, are powerful activators of the sympathoadrenomedullary system. Differential housing (single vs. group) and social defeat of rats is known to alter the activity of catecholamine-synthesizing enzymes in the medulla. The present studies examined the effect of 70 days of triad (3 rats per large cage) and individual housing of male rats on adrenal mRNA levels of tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT) and on TH protein levels. Behavioral ratings carried out at the triad formation indicated that dominant rats exhibited mostly offensive aggressive behaviors. By contrast, subordinate rats expressed primarily defensive behaviors, while the subdominant rats displayed intermediate levels of these behaviors. Overall, compared with single housing, triad housing resulted in lower gene expression for TH, DBH and PNMT and lower TH protein in the adrenals. Within triads, gene expression for these enzymes and TH protein concentration were higher in subordinate compared with dominant and subdominant rats. The dominant rats tended to have the lowest gene expression of these enzymes. These data indicate that in rodents, individual housing and a subject’s social rank have a differential impact on the regulation of catecholamine biosynthesis already during the process of gene expression of catecholamine biosynthetic enzymes in the adrenals.

To examine the hypothesis that Pavlovian autoshaping provides an animal learning model of drug abuse, two studies evaluated the induction of ethanol drinking by autoshaping procedures. In Experiment 1, the sipper tube conditioned stimulus (C S) contained saccharin/ethanol solution and was repeatedly paired with food as an unconditioned stimulus (US). The CS-US paired group consumed more of the 0.1% saccharin-6% ethanol solution than did the CS-US random group, revealing that autoshaping conditioned responses (CR) induce ethanol drinking not attributable to pseudo-conditioning. Experiment 2 employed saccharin-fading procedur es and showed that the paired vs random group differences in ethanol drinking were maintained, even as the saccharin was eliminate d from the solution. The results show that Pavlovian autoshaping procedures induce high volumes of ethanol drinking when the pres enta- tion of a sipper tube containing an ethanol solution precedes the response-independent delivery of food. The high volume of eth anol consumed in a brief period of time suggests that Pavlovian autoshaping may be a model of binge drinking.

Rat 22 kHz ultrasonic vocalizations (USVs) are thought to reflect an aversive behavioral state, perhaps a type of anxiety or fear, and have proven useful in the study of the neural mechanisms of these states. This paper describes a simple procedure for presentation of an aversive but non-painful air-puff stimulus for the elicitation of USVs from rats. When directed at the rat's dorsal or dorsolateral head and neck region, this stimulus reliably elicits ultrasonic vocalizations from nearly all rats tested and as such represents a valuable alternative to other stimuli such as aggressive encounters, electric shock, or acoustic startle. The USV response may attenuate with repeated testing, yet remains readily inducible and is therefore suitable for studies involving habituation. The materials for generating this stimulus and the accompanying testing procedure comprise an efficient method with which this aversively motivated rodent behavior can be examined. The potential utility of this technique in studies of aversively motivated behaviors and its relevance to studies of startle responding is discussed.

Studies of socially housed rodents have provided significant information regarding the consequences of exposure to stressors. Psychosocial stressors are known to alter the ingestion of ethanol and the activity of the dopaminergic neuronal system. Since both stressors and ethanol are known to affect the function of dopaminergic neurons, we employed amphetamine to assess the role of this neural system on the ingestion of ethanol by psychosocially stressed male rats. Male rats housed two per cage were designated as dominant or subdominant rats based on evaluations of agonistic behavior and body weight changes. The dyad-housed rats and a group of single-housed rats were sequentially assessed for ethanol intake after injections of saline or amphetamine (0.3, 0.9 or 2.7 mg/kg i.p.) both prior to dyad housing and subsequently again during dyad-housing. Prior to dyad housing ethanol intake of future subdominant rats was higher than that of future dominant rats. Dyad-housing significantly increased ethanol intake of dominant rats. Pre-dyad the highest dose of amphetamine potently depressed ethanol ingestion. Sensitivity to amphetamine's depressant effect on ethanol intake was higher at the dyad test in all subjects, most prominently in single-housed rats. In contrast to the single-housed rats, the dyad-housed rats displayed saccharin anhedonia. It can be concluded that dopaminergic system modulates, at least partially, the psychosocial stress-induced changes in ethanol intake. Furthermore, the level of ethanol ingestion at the pre-dyad test was predictive of future hierarchical status.

Osteocalcin, the most abundant member of the family of extracellular mineral binding gamma-carboxyglutamic acid proteins is synthesized primarily by osteoblasts. Its affinity for calcium ions is believed to limit bone mineralization. Several of the numerous hormones that regulate synthesis of osteocalcin, including glucocorticoids and parathyroid hormone, are also affected by stressful stimuli that require energy for an appropriate response. Based on our observations of OC responding to stressful sensory stimuli, the expression of OC in mouse and rat sensory ganglia was confirmed. It was thus hypothesized that the behavioral responses of the OC knockout mouse to stressful sensory stimuli would be abnormal. To test this hypothesis, behaviors related to sensory aspects of the stress response were quantified in nine groups of mice, aged 4-14 months, comparing knockout with their wild-type counterparts in six distinctly different behavioral tests. Resulting data indicated the following statistically significant differences: open field grooming frequency following saline injection, wild-type > knockout; paw stimulation with Von Frey fibers, knockout < wild-type; balance beam, knockout mobility < WT; thermal sensitivity to heat (tail flick), knockout < wild-type; and cold, knockout < wild-type. Insignificant differences in hanging wire test indicate that these responses are unrelated to reduced muscle strength. Each of these disparate environmental stimuli provided data indicating alterations of responses in knockout mice that suggest participation of osteocalcin in transmission of information about those sensory stimuli.

In rats, Pavlovian sign-tracking has been extensively evaluated as a model of compulsiveness in drug addiction and other addictive behaviors, but it remains unexplored in mice, a species with a wealth of genetically modified models, which makes it possible to examine gene-behavior relationships. In C57BL/6 mice, the most commonly used mouse strain for genetic studies, repeated pairings of lever conditioned stimulus (CS) with food unconditioned stimulus (US) induced Pavlovian conditioning of sign-tracking conditioned response (ST CR) performance of lever CS-directed approach, and Pavlovian conditioning of goal-tracking conditioned response (GT CR) performance of approach responses directed at the location of the food trough where the food US was delivered. The CS–US Paired group performed more ST CRs and more GT CRs during sessions 15–16 than did pseudoconditioning controls which received the lever CS and food US randomly with respect to one another. During sessions 15–16, all mice in the Paired group performed more GT CRs than ST CRs, and regression analysis revealed a positive relationship between an individual subject's tendency to perform ST CRs and GT CRs. The mice that performed more ST CRs during sessions 15–16 yielded higher plasma corticosterone levels. These data reveal stable and reliable acquisition and maintenance of ST CR performance and GT CR performance in mice; however, unlike in rats, ST CRs and GT CRs did not vary inversely within subjects. Corticosterone release, a pathophysiological marker of vulnerability to drug abuse, was positively related to ST CR performance.

The effect of the opioid receptor antagonist, naltrexone, on ethanol-induced changes in extracellular dopamine and serotonin in the nucleus accumbens was investigated using in vivo microdialysis in awake, freely moving rats. Locally applied ethanol (5% infused transprobe) resulted in substantial increases in dopamine in dialysate. Administration of naltrexone (cumulative dosing with 0.25-1.0 mg/kg i.p.) during ethanol administration dose-dependently reversed ethanol-induced increases in extracellular dopamine and its metabolite homovanillic acid but not serotonin. These data demonstrate an essential role for the endogenous opioid system in stimulation of dopamine release by ethanol in a brain area associated with reward and support the opioid system as a prime target for pharmacological modulation of the rewarding effects and consumption of ethanol.

Two experiments evaluated the effects of removing food presentations on the maintenance of drinking induced by experience with sipper — food pairings. In Exp 1, ethanol drinking was induced in non-deprived Long-Evans rats by Pavlovian conditioning procedures employing an ethanol sipper as conditioned stimulus (CS) and food pellet as unconditioned stimulus (US). The Paired/Ethanol group received presentations of the ethanol sipper CS followed immediately by the response-independent presentation of the food pellet US. The Random/Ethanol group received the ethanol sipper CS and food US randomly with respect to one another. For both groups, the concentration of ethanol in the sipper CS [(3%, 4%, 6%, 8% (vol./vol.)] was increased across sessions, and, as in previous studies employing low concentrations of ethanol in non-deprived rats (i.e., maintained with free access to food in their home cages), the two procedures induced comparable levels of sipper CS-directed ethanol drinking. Removing food US presentations had no effect on sipper CS-directed ethanol drinking in either group. In Exp 2, groups of non-deprived Long-Evans rats were trained either with water or ethanol in the sipper CS paired with food US. Removing food US presentations had no effect on ethanol drinking in the Paired/Ethanol group, but water drinking in the Paired/Water group declined systematically across sessions. Results indicate that food US presentations contribute to the maintenance of water drinking but not to the maintenance of ethanol drinking. Implications for accounts of ethanol drinking based on Pavlovian sign-tracking, behavioral economics and intermittent sipper procedures are considered.

We examined the effect of chronic treatment with ethanol on the dynamics of beta-adrenoceptor binding in left ventricular myocardium of rats. After treatment with BAAM (20 mg/kg i.p.), an irreversible inhibitor of beta-adrenoceptors, the inhibition of beta-adrenoceptor binding was less, and the recovery of receptor binding was faster in chronically ethanol-treated rats compared to the control animals given equicaloric dextrin maltose treatment. When intracellular beta-adrenoceptor recycling was inhibited with colchicine, cytoplasmic left ventricular beta-adrenoceptor binding was greater in ethanol-treated compared to dextrin maltose-treated animals. We conclude that the previously reported decreased functional activity of the beta-adrenoceptor-mediated system probably reflects the contribution of ethanol-mediated effects not entirely restricted to the receptor-binding mechanisms.

Activation of 5-HT receptors via reuptake inhibition, precursor loading, or inhibition of catabolism have consistently resulted in decreases in ethanol preference in rats. The objective of the present studies was to determine whether activation of the 5-HT1A receptor with gepirone, a selective agonist, decreases ethanol preference. Preference was first evaluated for ethanol solutions from 3 to 11%, in a free-choice situation with ethanol solution or tapwater available in the home cage. Male Sprague-Dawley rats consumed the most ethanol solution relative to water at a concentration of 6%. When ethanol (6% solution) was available to ethanol-habituated rats in a 1-hr restricted access situation, subjects consumed 5.9 ± 0.4 ml. Pretreatment with gepirone (0.46–4.6 mg/kg IP) resulted in a dose-dependent reduction in ethanol consumption in the restricted-access paradigm. The 5-HT reuptake inhibitor fluoxetine also resulted in dose-related decreases in ethanol consumption in restricted access. A subsequent experiment using a lower dose of fluoxetine also found a suppressive effect on ethanol intake. A single daily dose of gepirone failed to decrease the consumption of 6% ethanol when it was continuously available in the home cage. The short half-life of gepirone might explain its lack of effect in continuous access with only one daily dose. Gepirone decreased open-field activity at higher (2.3 to 4.6-mg/kg) doses, but did not affect rotorod performance at any dose (4.6–9.2 mg/kg) tested, whereas haloperidol (0.025–1.0 mg/kg) significantly decreased time on the rotorod. These results suggest that 5-HT1A receptor activation decreases ethanol intake in limited access and that the motorically disrupting effects of gepirone are not manifest under these conditions. © 1992 Wiley-Liss, Inc.

Pheromones are volatile chemical cues that in rodents originate in large part from the preputial glands and influence various behavioral and physiological processes. We have examined the effect of psychosocial stress on volatile compound composition of preputial glands of male rats. Rats were housed three per cage or singly for 70 days. Dominants had heavier preputials compared to subdominant and subordinate rats. Capillary gas chromatographic mass spectrometry identified 55 volatile preputial compounds: 17 did not differ between groups, while 26 compounds were higher in single-housed compared to triad-housed rats. Six compounds were higher in dominant, while another six were higher in both dominant and single-housed rats. We conclude that both housing condition and rank status have significant differential effects on the preputial volatile compounds.

Ethanol consumption and mental stress activate the sympathetic nervous system, which can adversely affect bone. We compared six groups of 10 young adult rats, three with and three without 2 h daily restraint stress. Two groups consumed food and water ad libitum, two received food and 6% (w/v) ethanol as drinking water, and two received the amount of food consumed by ethanol rats the previous day plus water ad libitum (pairfed). After 6 weeks, rats were killed. Plasma, femurs, lumbar vertebrae, and adrenals were harvested. Femoral dimensions were measured and biomechanical properties were tested by three-point bending. Plasma osteocalcin, vertebral osteocalcin mRNA levels, and adrenomedullary tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyl transferase (PNMT) mRNA levels were quantified. Daily restraint decreased weight gain and femoral length compared to dietary controls, and appeared to partially preserve bone strength, especially in calorie-restricted pairfed rats. Femoral strength was significantly affected by treatment in that bones of pairfed controls were weakest, ethanol drinkers were intermediate, and ad libitum restrained were strongest. Femoral yield load, displacement, and work at yield load were negatively correlated with TH and DBH mRNA levels, but not PNMT, suggesting a negative influence of norepinephrine. Plasma osteocalcin and dry weight of lumbar 3-5 vertebrae were unaffected; however, osteocalcin mRNA in second lumbar vertebrae was positively correlated with TH, DBH, and PNMT levels. Ethanol consumption at this level had little effect on femur morphology or strength. In contrast, the data suggested possible stimulation rather than inhibition of vertebral bone formation.

We examined the effect of various treatment schedules with ethanol on the development of tolerance and the severity of withdrawal in rats. Tolerance to ethanol was examined after a challenge dose of ethanol using rectal temperature, dowel performance, and tail flick response; open field activity and the startle response were determined during withdrawal. Animals treated daily with ethanol developed greater tolerance, and also lost it faster, compared with animals subjected to repeated cycles of 3 days of ethanol treatment followed by 3 drug-free days. Also, the severity of withdrawal was greater in animals treated daily with ethanol. In the second study, we examined the development of tolerance and withdrawal severity of animals subjected to three different schedules of daily ethanol administration. Overall, the animals receiving continuous infusion of ethanol showed the most severe withdrawal and had, except for dowel performance, the fastest loss of tolerance to ethanol.

The literature on alcohol and stress in human subjects carried out since 1981 is reviewed. The review covers selected aspects of the interaction of alcohol and stress. (1) Most of the review focuses on the role of stress on alcohol ingestion. Retrospective research based on data from the Health and Nutrition Examination Survey indicated an increase in alcohol consumption with anxiety in certain groups of, as yet not well characterized, individuals. For example, although still insufficiently documented, stress does not appear to play a significant role in alcohol ingestion by women and the elderly. By contrast, stress does appear to play a role in the control of alcohol ingestion by adolescents. Prospective studies employing questionnaire-interview formats generally support an effect of stress on alcohol ingestion. However, studies employing male college aged social drinkers did not find a correlation between levels of stress and ingestion of alcohol. Alcoholics also differ in the reasons for drinking alcohol, but generally ingest alcohol to lessen anxiety/stress. It is clear that the Tension Reduction Hypothesis as originally postulated is no longer adequate. Many new models based on an interaction of alcohol and stress have been proposed to explain the control of alcohol consumption. Considering the multidimensionality of factors that appear to contribute to the control of alcohol ingestion, it is unlikely that a single model could possibly be relevant to alcohol ingestion under all conditions. More likely different models may be relevant to alcohol consumption under specific conditions, or for specific populations. (2) Alcohol has been reported to decrease anxiety in agoraphobics. The self-medication by agoraphobics may contribute significantly to their alcohol abuse. (3) Alcohol has also been reported to decrease tremor of the hands in stressed subjects as well as in patients with essential tremor. (4) Although a number of studies have employed electrodermal activity in studies aimed at the interaction of alcohol and stress, the results have been rather inconsistent. (5) The controversy on the purported beneficial effect of alcohol on the cardiovascular system persists. A number of studies have shown a J- or U-shaped relationship between alcohol ingestion and incidence of coronary heart disease. Alcohol may also influence stress-induced changes in blood pressure. Although a number of studies have demonstrated lower blood pressure in individuals ingesting less than two drinks per day compared with abstainers or heavy alcohol imbibers, the evidence is not conclusive. (6) It is not clear whether the interaction of alcohol and stress involves alterations in plasma catecholamines. Alcohol may lower elevated plasma catecholamines induced by some, but not all, stressors. The inconsistencies in data in the reviewed literature most likely reflect some of the many variables associated with alcohol and stress research. These are also briefly reviewed and include subject-, drug- and stress-related variables.

Research on the interaction of ethanol (ET) and stress published since 1981 is reviewed. Chronic physical stressors were found to increase the ingestion of ET compared to nonstressed animals. With foodshock, ingestion of ET decreased during the stress session but rose afterwards. The elevation of ET ingestion produced by daily immobilization was long-lasting and was related to individual initial preference for ET. Psychological stressors also increased ingestion of ET. In rat colonies, dominant rats ingested less ET, whereas submissive rats had the highest intake. Factors that modify the ingestion of ET include neonatal experience and REM sleep deprivation. Early weaning increased, while postnatal handling decreased preference for ET. The effect of postnatal handling may be influenced by genetics. Stress, applied during adult life or prenatally, modifies some, but not all, the acute effects of ET. There were marked individual differences in the interaction of ET and stress with respect to ingestion of ET. Conversely, ET may modify stress-induced behavioural and neurochemical changes. This interaction may be stressor specific. Some stressors increase the ET's effects, whereas others may decrease or not affect them. In brain, ET has been shown to lessen the stress-induced decrease in noradrenaline and 5-hydroxytryptamine (serotonin) levels and those in noradrenaline turnover and alpha 1-receptor binding. Stress-induced changes in plasma catecholamines, corticosterone, non-esterified fatty acids and amino acids, and in the decline in adrenal catecholamines are also lessened by pretreatment with ET. Possible mechanisms for the ET-stress interaction are discussed. These include mediation via the GABA-benzodiazepine-ionophore complex, endogenous opioids, the hypothalamo-pituitary-adrenocortical axis and the noradrenergic system.

In rodents the preputial glands are one of the major sources of pheromones. These volatile chemosignaling compounds are known to elicit specific behavioral and physiological effects in their conspecifics. While social stress can alter both the behavior and hormonal status of rodents, little is known about its influence on the volatile constituents of the preputial glands. We have examined the composition of volatile compounds in the preputial glands of gonadally intact male rats housed for 70 days in either unisex triads (three/cage) or singly. The rank status of triad-housed rats was based on quantitative behavioral assessments taken during the initial 30 min of triad housing. Dominant rats had heavier preputial glands compared to subdominant and subordinate rats. Capillary gas chromatography-mass spectrometry identified 56 volatile preputial compounds, of these 17 did not differ between groups while 26 compounds were significantly higher in the single-housed compared to the triad-housed rats. Six additional volatile compounds were higher in the dominant compared to the other 3 groups, while another six compounds were higher in both the dominant and single-housed rats compared to the subdominant and subordinate rats. It can be concluded that both housing condition and social rank status have significant but different effects on the composition of volatile compounds found in preputial glands of male rats. The physiological and behavioral significance of these changes in preputial gland volatile compound composition in rats remain to be investigated.

Psychosocial stress is known to enhance anxiety levels in rodents. The present study evaluated the effect of long-term ingestion of ethanol (EtOH) on anxiety levels of male Long Evans rats housed either singly or in triads (three/cage). Based on measures of offensive and defensive behaviors, triad-housed rats were designated as being dominant, subdominant or subordinate. The effect of chronic ingestion of a 6% EtOH solution was assessed on behaviors in the elevated plus maze (EPM) test, and on air-puffs elicited 22 kHz ultrasonic vocalizations (USV). EtOH naive dominant rats showed less anxiogenic-like (open arms time) and displacement behavior (grooming), but more risk assessment behavior (stretch-attend postures) than their cage-mates or the single-housed rats. Intake of EtOH prior to the EPM test was lower in dominant and single-housed rats compared to subdominant and subordinate rats. Triad-housed rats, but not the single-housed rats, decreased their intake of EtOH after the EPM test. Overall, EtOH intake had an anxiolytic effect in all rats, but the effect was most prominent in single-housed rats. Furthermore, EtOH intake decreased air-puff induced USVs of triad-housed rats, but increased USVs of single-housed rats. These data indicate that housing condition and rank status influence the emotional state of male rats. Furthermore, the anxiolytic effect of voluntarily ingested EtOH was depended on these variables.

Aims: Intermittent presentations of the ethanol sipper have been reported to induce more ethanol drinking in rats than when the ethanol sipper was continuously available during the session. This intermittent sipper effect was observed in a social drinking situation, in which subjects experienced intermittent opportunities to interact briefly with a conspecific rat. The objective of this study was to evaluate the effects of the intermittent sipper procedure in situations providing for intermittent presentations of food, and, in addition, in situations that do not provide for intermittent presentations of another rewarding event. Methods: Four groups of male Long-Evans hooded rats, arranged in a 2 × 2 factorial design with two levels of Sipper Procedure (Intermittent vs Continuous) and two levels of Food procedure (Food vs No Food), were trained in drinking chambers. During each daily session, Intermittent Sipper groups received access to the ethanol sipper during each of 25 trials of 10 s each, while Continuous Sipper groups had access to the ethanol sipper during the entire session (∼30 min). During each session, Food groups received 25 presentations of food pellets while No Food groups received no food pellets. Ethanol concentrations in the sipper [3, 4, 6, 8, and 10% (vol./vol.)] increased across sessions. Results: More rapid escalation of ethanol intake was observed in the Intermittent Sipper groups than in the Continuous Sipper groups, and this effect was observed in both the Food and No Food conditions ( P 's < 0.05), which did not differ from one another. Conclusions: Intermittent Sipper procedures provide less access to the ethanol sipper, yet induced more ethanol drinking than Continuous Sipper procedures. The intermittent sipper effect is not dependent on presentations of food. Implications for schedule-induced polydipsia and Pavlovian autoshaping are discussed. ( Received 19 August 2005; first review notified 31 October 2005; in revised form 31 December 2006; accepted 6 January 2006)

Psychosocial stress, including social rank status, has been shown to alter spontaneously occurring behaviors in rodents as well as the behavioral effects of drugs of abuse. In this study, rats were repeatedly evaluated in a modified open field following: their initial exposure, and after intraperitoneal injections of saline and 0.75 g/kg ethanol (EtOH). All subjects were first tested while under single housing conditions, then again following 35 days of differential housing (singly or 3 rats/cage) with social status determined by scoring agonistic behavior at triad formation. The data suggest that (1) future subordinate rats differed with respect to specific aspects of behavior displayed in a 'novel' open field arena, (2) future subordinate rats were more emotional since they showed greater "anxiety-like" behavior and less exploratory behavior, (3) subordinate rats were more impaired by the saline injection stress, (4) subordinate rats were more sensitive to the depressant effects of EtOH, (5) grooming behavior did not show habituation, in contrast to the other behaviors, but showed sensitization on the second test. Overall, subordinate rats may have differed from their cage mates in innate anxiety, and this may underlie their distinct response to both stressors and EtOH. Furthermore, while EtOH had mostly stimulant effects in naive rats, psychosocial stress and/or repeated testing resulted in enhancement of EtOH's depressant effects.

Three groups of male Long–Evans hooded rats were assessed for effects of social opportunity on drinking of ethanol or water. The ethanol/female group received intermittent presentations of a sipper containing ethanol that was followed by 15 s of social interaction opportunity with a female rat. The ethanol/male group received similar training except the social interaction opportunity was with a male rat. The water/female group received training similar to the ethanol/female group except that the sipper contained water. For the ethanol groups, the concentration of ethanol [3%, 4%, 6%, 8% and 10% (vol/vol)] in the sipper was increased across sessions. With 10% ethanol in the sipper, social opportunity with females induced more drinking and ethanol intake than did social opportunity with males. Social opportunity with females induced more intake of ethanol than water. Post-session plasma samples revealed social opportunity with females induced higher corticosterone and testosterone levels than did social opportunity with males, irrespective of the sipper fluid. This study documents, for the first time, an inter-gender effect on ethanol drinking in rats.

Psychosocial stress is known to alter behavior of rodents. While psychosocial stress may alter the response to some drugs, the response to ethanol (EtOH) has not been evaluated.To examine open-field behaviors of triad- and singly housed rats treated acutely or voluntarily ingesting EtOH.Triad-housed rats were categorized as dominant, subdominant, or subordinate based on assessments of offensive and defensive behaviors. Open-field behaviors were monitored during a 10-min test in rats voluntarily ingesting a 6% solution of EtOH for 2 weeks (1), and after an i.p. injection of saline, 0.5 or 1.0 g kg(-1) of EtOH (2).Daily intake of EtOH was highest in subdominant and lowest in dominant rats. Overall, open-field behaviors did not differ between water- and EtOH-consuming triad- or singly housed rats. The 0.5-g kg(-1) dose of EtOH enhanced locomotor activity only in triad-housed rats, center entries primarily in singly housed rats, and head-poke behavior in dominant and singly housed rats. Rearing behavior was not altered by the 0.5-g kg(-1) dose, but in singly housed rats, rearing behavior was depressed by the 1.0-g kg(-1) dose. This larger dose of EtOH had no effect on the other behaviors.EtOH's effects on open-field behaviors show behavioral specificity and vary with the subject's housing and/or rank status. EtOH's acute anxiolytic-like effect was primarily evident in singly housed rats.

Previous studies of autoshaping of drinking report a positive relationship between experience with autoshaping procedures and drinking, but this effect was confounded with age, as the rats were older when they drank more. The present experiment evaluated the effects of the age of male Long-Evans hooded rats [90-days old (Younger group) vs. 135 days old (Older group)], at the beginning of the study, on drinking induced by Pavlovian autoshaping procedures. Autoshaping procedures consisted of pairings of sipper conditioned stimulus (CS) with food unconditioned stimulus (US). Rats were deprived of neither food or fluid, and sweeteners were not employed at any time during the study. For all rats (n = 32), during sessions 1-10, the sipper CS contained water. Thereafter, for rats in the Ethanol groups (n = 20), the sipper CS contained ethanol, with the concentration (1, 2, 3, 4, 5, 6%, v/v) increasing across autoshaping sessions. For rats in the Water groups (n = 12), throughout the experiment the sipper CS contained tap water (0% ethanol). Rats in the Younger group drank more ethanol and more water from the sipper CS than rats in the Older group, and across age groups there was more ethanol drinking than water drinking, an effect unlikely due to foraging for calories. Data support the hypothesis that ethanol’s pharmacological effect was to enhance autoshaping, resulting in a positive feedback loop inducing still more ethanol drinking. The younger rats were more vulnerable to autoshaping effects. Implications for models of addiction are discussed.

This study examines the effect of chronic administration of the anabolic androgenic steroid nandrolone decanoate (ND) on dominant and subordinate male rats in a pair-housed condition. Pair-housed rats were assessed for dominance status based on their behavior and alterations in body weights. Throughout the study the rats were allowed limited social interactions on a daily basis. At all other times, a Plexiglas divider kept the rats separated, allowing olfactory and visual contact between the cage mates while preventing significant physical contact. One week into the study all subjects were subcutaneously implanted with a pellet that continuously infused either ND (15 mg/kg/day) or placebo for 21 days. Following the pellet implant, behavioral tests including reassessment for dominance status, and a conditioned fear test were conducted over a period of approximately 2 months to investigate possible long-term changes. The main finding is that during the allowed social interactions, the dominant ND-pretreated rats spent more time on highly aggressive behaviors than the dominant placebo-treated rats. In addition, the probability for highly aggressive behaviors was maintained for the ND-treated rats throughout the study, whereas it was decreased for the placebo-treated rats. The ND-treated subordinate rats showed less fear in a potential threatening situation compared to placebo-treated controls. These findings support the relatively long-term behavioral changes that have been seen in humans after abuse of ND and other anabolic androgenic steroid compounds.

Most alcohol researchers do not address the effects of intoxication on the sympatho-adrenomedullary system response to stressful situations. We previously determined that rats consuming nearly 9 g ethanol (EtOH) per kg body weight per day in liquid diet form for 1 week increased adrenal gene expression of enzymes for catecholamine synthesis that was further elevated by acute IMMO. We hypothesized that the response to chronic mild stressors would also be altered after consumption of lower concentrations of EtOH in drinking water. Two experiments were conducted: 10% w/v for 4 weeks or 6% w/v for 7 weeks +/- wire mesh restraint (WMR). These were compared with ad libitum (adlib) and pair-fed control rats. Adrenal gene expression of catecholamine synthesizing enzymes was assayed. Tyrosine hydroxylase gene expression was elevated 80% to 90% by alcohol consumption in both experiments (P0.001) compared with adlib control rats. Dopamine betab-hydroxylase and phenylethanolamine-N-methyl transferase gene expressions were unaffected by 10% alcohol (P0.05) but were increased by 6% alcohol (P0.01). WMR decreased already elevated gene expression of all three enzymes. Pair feeding to 6% EtOH drinkers also increased gene expression for the three enzymes but was decreased by WMR, although not to levels of adlib rats. Increased gene expression for adrenal synthesis of catecholamines in response to repeated alcohol consumption increases the likelihood that the subject can respond physiologically to acute or chronic stress. This may have life-saving consequences in humans and in animals known to consume fermented materials and may contribute to increased aggressive behavior.

Neuroendocrine and behavioral profiles of group-housed rodents differ from those of singly-housed ones. Subordinate rats have elevated plasma corticosterone (CORT) concentration and impaired activity of the hypothalamic-pituitary-adrenal (HPA) axis compared to dominant cagemates. However, little is known about the effects of social hierarchy on other stress-related hormones. We examined plasma prolactin (PRL) and CORT responses to saline and ethanol (EtOH) injections, and 1 month later to dexamethasone (DEX) and corticotropin-releasing hormone (CRH) challenges of group- (triad) and single-housed male rats over a period of 225 days. Social status was determined from behaviors displayed upon initial triad housing. Subordinate rats had lower basal PRL and higher CORT compared to dominant rats. The injection of EtOH (1.25 g/kg) depressed PRL and elevated CORT levels significantly more than the saline injection only in dominant and singly-housed rats. DEX increased PRL levels, most strikingly in dominant rats, and suppressed CORT only in dominant rats. After CRH challenge, plasma CORT increased in all groups, subdominant and subordinate rats displaying blunted responses. Our data demonstrate that social rank and housing conditions affect plasma PRL and CORT concentrations, and modify responses to EtOH, possibly reflecting impairments of HPA axis regulation in socially-housed rats.

Effects of autoshaping procedures (Paired versus Random) and sipper fluid [chlordiazepoxide (CDP) versus water] on sipper-directed drinking were evaluated in 32 male Long-Evans rats maintained with free access to food and water. For the Paired/CDP group (n = 16), autoshaping procedures consisted of the presentation of the CDP sipper conditioned stimulus (CS) followed by the response-independent presentation of the food unconditioned stimulus (US). The concentration of CDP in the sipper CS (0.05, 0.10, 0.15, 0.20, and 0.25 mg/ml CDP) was increased across sessions. The Paired/Water group (n = 8) received only water in the sipper CS. The Random/CDP group (n = 8) received the CDP sipper CS and food US randomly with respect to one another. The Paired/CDP group drank significantly more of the 0.20 mg/ml and 0.25 mg/ml CDP solutions than the Random/CDP control, and more fluid than the Paired/Water control group when the sipper CS for the Paired/CDP group contained the three highest concentrations of CDP. CS-Only extinction procedures reliably reduced sipper CS-directed drinking in the Paired/CDP and the Paired/Water groups, but not in the Random/CDP group. Data are consistent with the hypothesis that Pavlovian autoshaping procedures induce sipper CS-directed drinking of CDP in rats deprived of neither food nor fluid. Implications for the autoshaping model of drug abuse are discussed.

Aims: The present study evaluates the effects of pairing ethanol sipper conditioned stimulus (CS) with social opportunity unconditioned stimulus (US) on CS-directed ethanol drinking in rats. Subjects were Long-Evans male rats (n = 32) deprived of neither food nor water, and the concentration of unsweetened ethanol (3 to 16%) in the sipper CS was increased across sessions. Methods: Group Paired/Ethanol (n = 12) received the ethanol sipper CS for 10 s immediately prior to 15 s of social opportunity US. Control groups received water rather than ethanol in the sipper CS (Paired/Water), or ethanol sipper CS and US presentations randomly (Random/Ethanol), or ethanol sipper CS but no social opportunity US (Sipper Only). Results: Mean ethanol intake in the Paired/Ethanol and Random/Ethanol groups exceeded 1.0 g/kg when the sipper CS contained 12%, 14% and 16% ethanol, and higher fluid intakes were observed in the Paired/Ethanol and Random/Ethanol groups than in the Paired/Water and Sipper Only groups. Conclusions: Social opportunity increased ethanol drinking, and more so than water drinking; however, autoshaping did not induce additional ethanol drinking beyond that observed in random controls.

In two studies, we evaluated the effects of ethanol concentration and trial spacing on Pavlovian autoshaping of ethanol drinking in rats. In these studies, the brief insertion of an ethanol sipper conditioned stimulus (CS) was followed by the response-independent presentation of food unconditioned stimulus (US), inducing sipper CS-directed drinking conditioned responses (CRs) in all rats. In Experiment 1, the ethanol concentration in the sipper CS [0%-16% volume/volume (vol./vol.), in increments of 1%] was systematically increased within subjects across autoshaping sessions. Groups of rats received sipper CS-food US pairings (Paired/Ethanol), a CS-US random procedure (Random/Ethanol), or water sipper CS paired with food US (Paired/Water). In Experiment 2, saccharin-fading procedures were used to initiate, in the Ethanol group, drinking of 6% (vol./vol.) ethanol in 0.1% saccharin or, in the Water group, drinking of tap water in 0.1% saccharin. After elimination of saccharin, and across days, the duration of access to the sipper CS during each autoshaping trial was increased (5, 10, 12.5, 15, 17.5, and 20 s), and subsequently, across days, the duration of the mean intertrial interval (ITI) was increased (60, 90, 120, and 150 s). In Experiment 1, Paired/Ethanol and Random/Ethanol groups showed higher intake of ethanol, in terms of grams per kilogram of body weight, at higher ethanol concentrations, with more ethanol intake recorded in the Paired/Ethanol group. In Experiment 2, the Ethanol group drank more than was consumed by the Water group, and, for both groups, fluid intake increased with longer ITIs. Results support the suggestion that autoshaping contributes to sipper CS-directed ethanol drinking.

The effects of autoshaping procedures (paired vs. random) and sipper fluid (ethanol vs. water) on sipper-directed drinking were evaluated in male Long-Evans rats maintained with free access to food and water. For the paired/ethanol group (n=16), autoshaping procedures consisted of presenting the ethanol sipper (containing 0% to 28% unsweetened ethanol) conditioned stimulus (CS) followed by the response-independent presentation of food unconditioned stimulus (US). The random/ethanol group (n=8) received the sipper CS and food US randomly with respect to one another. The paired/water group (n=8) received only water in the sipper CS. The paired/ethanol group showed higher grams per kilogram ethanol intake than the random/ethanol group did at ethanol concentrations of 8% to 28%. The paired/ethanol group showed higher sipper CS-directed milliliter fluid consumption than the paired/water group did at ethanol concentrations of 1% to 6%, and 15%, 16%, 18%, and 20%. Following a 42-day retention interval, the paired/ethanol group showed superior retention of CS-directed drinking of 18% ethanol, relative to the random/ethanol group, and superior retention of CS-directed milliliter fluid drinking relative to the paired/water group. When tested for home cage ethanol preference using limited access two-bottle (28% ethanol vs. water) procedures, the paired/ethanol and random/ethanol groups did not differ on any drinking measures.

Effects of experience with Pavlovian autoshaping procedures on lever-press autoshaping conditioned response (CR) performance and 3H-8-OH-DPAT-labeled binding of 5-HT1a receptors as well as 125I-LSD-labeled binding of 5-HT2a receptors were evaluated in four groups of male Long-Evans hooded rats. Two groups of rats (Group Paired High CR and Group Paired Low CR) received Pavlovian autoshaping procedures wherein the presentation of a lever (conditioned stimulus, CS) was followed by the response-independent presentation of food (unconditioned stimulus, US). Rats in Group Paired High CR (n=12) showed more rapid CR acquisition and higher asymptotic levels of lever-press autoshaping CR performance relative to rats in Group Low CR (n=12). Group Omission (n=9) received autoshaping with an omission contingency, such that performing the lever-press autoshaping CR resulted in the cancellation the food US, while Group Random (n=9) received presentations of lever CS and food US randomly with respect to one another. Though Groups Omission and Random did not differ in lever-press autoshaping CR performance, Group Omission showed significantly lower levels of 3H-8-OH-DPAT-labeled 5-HT1a binding in post-synaptic areas (frontal cortex, septum, caudate putamen), as well as significantly higher plasma corticosterone levels than Group Random. In addition, Group Random showed higher levels of 3H-8-OH-DPAT-labeled 5-HT1a binding in pre-synaptic somatodendritic autoreceptors on dorsal raphe nucleus relative to each of the other three groups. Autoradiographic analysis of 125I-LSD-labeled 5-HT2a receptor binding revealed no significant differences between Groups Paired High CR and Paired Low CR or between Groups Omission and Random in any brain regions.

Aims: This study asks if repeated Pavlovian pairings of a sipper tube (conditioned stimulus, CS) with food (unconditioned stimulus, US) will induce Pavlovian autoshaping conditioned responses (CRs), consisting of drinking of either 6% ethanol or wat er from the sipper CS. This study also tests predictions derived from the autoshaping model by asking if sipper CS-directed drinking wi ll be retained, despite the absence of training for several weeks, and, in addition, if drinking rate is a negative function of sippe r CS duration. Methods: Autoshaping procedures, conducted in two daily sessions, consisted of the brief insertion of the sipper tube CS followed by the response-independent presentation of food US. For the Ethanol group ( n = 8), the sipper CS contained 6% ethanol, whereas for the Water group (n = 8), the sipper CS contained tap water. Saccharin fading procedures were employed, whereas for both groups, during days 1-19, the sipper CS contained 0.1% saccharin, and thereafter across training days the concentration of saccharin was gradu ally reduced (0.07, 0.035, 0.0%). Following elimination of saccharin, both groups were maintained in their home cages during a 27-da y retention interval, and then re-evaluated for autoshaping of drinking of unsweetened ethanol and water. Thereafter, across days , the duration of access to the sipper CS (5.0, 7.5, 10.0, 15.0 s) during each autoshaping trial was increased. Results: Both groups increased drinking across the first 19 days of training with sipper CS-food US pairings, and, at 0.0% saccharin, the Ethanol group consumed 14.76 ml of 6% ethanol per day, resulting in a daily ethanol consumption of 2.77 g/kg. For both groups, daily levels of drinkin g before and after the 27-day retention interval were comparable, attesting to the durability of the acquired drinking effects. At each CS duration, the Ethanol group consumed more millilitres of fluid per day than did the Water group, and for the Ethanol group, peak drinking of 24.0 ml of 6% ethanol per day was observed at the 10 s CS duration. For both groups, drinking rate (millilitres of fluid consum ed per second of CS duration), was a declining monotonic function of CS duration, resulting in a daily ethanol consumption of ~4.2 g/k g for the Ethanol group. Conclusions: These data reveal that these sipper CS-food US autoshaping procedures induce drinking in rats that is durable and negatively related to increasing CS duration. The effects of both variables are consistent with the hypothesis t hat drinking from the sipper CS is a Pavlovian autoshaping CR. Autoshaping of drinking in the Water group is observed despite the absence of water deprivation, and even more fluid is consumed by the Ethanol group than by the Water group. The high volumes of ethanol consumed during brief daily sessions suggest that Pavlovian autoshaping procedures may provide an animal learning model of binge drinkin g.

Pavlovian autoshaping conditioned responses (CRs) are complex sequences of conditioned stimulus (CS)-directed skeletal-motor responses that are elicited by CS objects predictive of food unconditioned stimulus (US). Autoshaping CRs are observed under conditions known to be conducive to elevations in plasma corticosterone levels, as, for example, in response to the eating of food as well as in response to signals predictive of food. Two experiments investigated the relationships between Pavlovian autoshaping procedures, the performance of Pavlovian autoshaping CRs, and plasma corticosterone levels in male Long–Evans rats. In Experiment 1, rats in the CS–US paired group (n=30) were given 20 daily sessions of Pavlovian autoshaping training wherein the insertion of a retractable lever CS was followed by the response-independent presentation of the food US. Tail blood samples obtained after the 20th autoshaping session revealed higher plasma corticosterone levels in the CS–US paired group than in the CS–US random control group (n=10). In Experiment 2, rats (n=35) were assessed for basal plasma corticosterone levels 2 weeks prior to autoshaping training. Plasma samples obtained immediately following the first autoshaping session, and prior to the acquisition of lever-press autoshaping CR performance, revealed higher plasma corticosterone levels in the CS–US paired group (n=24) relative to basal levels. This effect was not observed in the CS–US random control group (n=11). Data suggest that corticosterone release is a physiological endocrine Pavlovian CR induced by lever CS–food US pairings during Pavlovian autoshaping procedures, rather than a by-product of autoshaping CR performance. Implications of the link between autoshaping procedures and corticosterone release are discussed.

Autoshaping conditioned responses (CRs) are reflexive and targeted motor responses expressed as a result of experience with reward. To evaluate the hypothesis that autoshaping may be a form of impulsive responding, within-subjects correlations between performance on autoshaping and impulsivity tasks were assessed in 15 Long-Evans hooded rats. Autoshaping procedures [insertion of retractable lever conditioned stimulus (CS) followed by the response-independent delivery of food (US)] were followed by testing for impulsive-like responding in a two-choice lever-press operant delay-of-reward procedure (immediate small food reward versus delayed large food reward). Delay-of-reward functions revealed two distinct subject populations. Subjects in the Sensitive group (n=7) were more impulsive-like, increasing immediate reward choices at longer delays for large reward, while those in the Insensitive group (n=8) responded predominantly on only one lever. During the prior autoshaping phase, the Sensitive group had performed more autoshaping CRs, and correlations revealed that impulsive subjects acquired the autoshaping CR in fewer trials. In the Sensitive group, acute injections of ethanol (0, 0.25, 0.50, 1.00, 1.50 g/kg) given immediately before delay-of-reward sessions yielded an inverted U-shaped dose-response curve with increased impulsivity induced by the 0.25, 0.50, and 1.00 g/kg doses of ethanol, while choice strategy of the Insensitive group was not influenced by ethanol dose. Ethanol induced impulsive-like responding only in rats that were flexible in their response strategy (Sensitive group), and this group also performed more autoshaping CRs. Data support the hypothesis that autoshaping and impulsivity are linked.

Approach responses, consummatory behaviors, and directed motor responses maintained by food reward resemble autoshaping CRs and are increased by lower doses of ethanol. This study evaluated the effects of presession i.p. injections of ethanol doses (0.00, 0.25, 0.50, 0.70. or 1.00 g/kg) on the acquisition of lever-press autoshaping CR performance in groups of male Long-Evans hooded rats. Paired groups received 15 daily sessions of Pavlovian autoshaping procedures, wherein the insertion of a retractable lever for 5 s (CS) was followed by the response-independent presentation of food (US). Ethanol facilitated lever-press autoshaping CR acquisition, as revealed by dose-related increases in the number of trials on which CRs were performed. The form of the dose-effect curve was inverted U-shaped with maximal responding induced during sessions 1-5 by the 0.70 g/kg ethanol dose. A similar dose-effect curve was observed during sessions 11-15, revealing that the effects of ethanol on autoshaping CR performance were relatively stable. A pseudoconditioning control group injected presession with 0.50 g/kg ethanol received training wherein the food US was presented randomly with respect to the lever CS. Few lever-presses were performed by the Random 0.50 group, indicating that ethanol's effects on autoshaping CR acquisition and maintenance observed in the Paired 0.50 group were not due to its psychomotor activating effects. A non-injection control group performed more autoshaping CRs than did the control group injected presession with saline, indicating that daily presession i.p. injections per se suppress autoshaping CR performance. Results reveal that low doses of ethanol enhance Pavlovian conditioning of directed motor and consummatory-like responding maintained by food reward. Implications for autoshaping accounts of impulsivity and drug abuse are considered.

Using behavioral and physiological measures, we compared the rates of development and decay of acute and chronic tolerance to ethanol (ET) and the severity of the withdrawal syndrome. Male rats were treated with 6, 9, or 12 g/kg/day ET or equicaloric dextrin maltose, delivered intragastrically. Although treatment duration varied, the total dose of ET was kept constant at 162 g/kg/rat for the three groups. The effects of a cumulative test dose of ET or equicaloric dextrin maltose, after exposure to a total of 0, 42, 83, 126, and 162 g/kg ET, and at 3, 5, and 7 days after termination of the chronic treatments, were evaluated on rectal temperature, dowel performance, and tail-flick and startle responses. After the initial five tolerance tests, chronic treatments were discontinued and rats were tested in a modified open-field apparatus and for their startle response to an auditory stimulus at 8, 12, 16, 20, 32, and 40 h later. With all measures, little tolerance developed in the 6-g/kg/day group. On the other hand, development of chronic tolerance was fastest in rats treated with the 12-g/kg/dose of ET. Chronic tolerance did not develop to ET's depressant effect on the startle response. Acute tolerance declined with chronicity of treatment in animals given the largest daily dose of ET. During withdrawal, and in contrast to the dextrin maltose-treated animals, there was impairment in all measures taken during the modified open-field test and hypersensitivity of the startle response for all three chronic ET-treated animals. Greatest behavioral impairment occurred in animals treated with 12 g/kg/day, and some impairment was still evident 40 h after the last dose of ET. Thus, the severity of the withdrawal syndrome was greatest in the group displaying the most acute and chronic tolerance.

Research on the interaction of alcohol and stress on the cardiovascular system published since 1981 is reviewed. Important variables that can modify the interaction of alcohol and stress are also discussed. Consistent findings have come from studies on stress-induced tachycardia which has been shown to be decreased by alcohol ingestion. Evidence from clinical, cohort, case-control, epidemiological research indicates that long-term ingestion of alcohol is associated with lower risk of coronary heart disease. Less clear is the association of the risk of hypertension and alcohol ingestion. Primarily in women, there might be a threshold low level of alcohol consumption which is not associated with the development of hypertension. With some stressors, alcohol may depress the stressor-induced elevation of plasma catecholamines. Mechanisms believed to mediate the described alcohol-stress interaction are discussed. Existing evidence support the following mechanisms: mediation via changes in plasma lipoproteins in the case of coronary heart disease and changes in plasma calcium levels for the blood pressure effects.

Male rats were administered either ethanol (6-8 g/kg/day) or dextrin-maltose, an isocaloric equivalent, for two weeks prior to a 24-hour resident-intruder test. After the first 20 minutes of the aggression test residents showed a greater increase in norepinephrine than intruders (216% vs. 97%), while intruders showed a greater increase in epinephrine (394% vs. 51%) and corticosterone (338% vs. 129%) than residents. Ethanol administration increased the initial epinephrine response of intruders almost two-fold compared to dextrin-maltose intruders. After 24 hours of aggression testing plasma norepinephrine was still elevated in residents (92%) and intruders (71%), however, only intruders continued to show an elevation in plasma corticosterone (98%) and epinephrine (107%). Using a cumulative dose-response technique, the dose of isoproterenol required to produce 50% of the maximal heart rate response (ED50) increased in intruders by 108% following aggression testing with ethanol intruders showing significantly smaller mean change. The increase in ED50 was related to drug type, behavior, and plasma corticosterone and epinephrine levels. Rats treated with ethanol had a greater beta-adrenoceptor density than control rats. However, no relationship was found between receptor density and the other measures in this study.

Previous research suggested that low doses of ethanol (ETOH) may have a protective effect against stress: We now report confirmation and extension of that preliminary study. Male Sprague-Dawley rats were injected with 0.50 g/kg ETOH (10% w/v) or an equivalent volume of saline and randomly assigned to one of four groups in Experiments I and II (saline-stress, saline-nonstress, ethanol-stress, ethanol-nonstress). In Experiment III, only two groups were tested (ethanol-stress, saline-stress). The stressors consisted of 30 trials (intertrial interval 60 s) of a 2-s duration 0.40 mA foot shock (Experiment I), 90 min restrain stress at 21 degrees C (Experiment II) or 10 min tail-pinch (Experiment III). In Experiments I and II, plasma nonesterified fatty acids (NEFA) were significantly increased in the saline-stress groups compared to the saline-nonstress or ethanol-nonstress groups. In contrast, subjects treated with ETOH and stress had significantly lower levels of plasma NEFA than saline-stress subjects in Experiments I and III. Plasma corticosterone was significantly elevated in response to stress. Subjects in the ethanol-stress groups had significantly lower levels of plasma corticosterone than subjects in the saline-stress group (Experiments I and II). These results suggest that ETOH has some protective effect against stress-induced increases in plasma corticosterone and NEFA. Furthermore, this finding may be generalized to several different types of stressors.

We performed an experiment to study the effects of 2-week ethanol regime on intermale aggression in rats using a 24-hour resident-intruder test. The behavior of both resident and intruder rats was studied in this experiment. In addition, plasma levels of corticosterone (CORT) and testosterone (TEST) were measured for all subjects to determine the relationship between ethanol-induced changes in CORT and TEST levels and agonistic and defensive behaviors as well as to study behavior-induced changes in CORT and TEST

Neurotransmitter mechanisms that mediate the effect of ethanol on urine output were examined in male rats. To establish the neuronal systems involved in the diuretic action of ethanol, urine output was evaluated in animals pretreated with various pharmacological agents. The intraventricular administration of norepinephrine (1.5-12 micrograms) increased the diuresis produced by a 1.25 g/kg dose of ethanol. Clonidine (2.5, 5.0 micrograms), an alpha 2-receptor agonist, also increased ethanol diuresis, while the alpha 1-receptor antagonist phentolamine (14 and 35 micrograms) reduced it. beta 1,2-Adrenergic blocker propranolol (5 and 10 micrograms) significantly depressed ethanol-induced urine output. Conversely the beta 2,2-noradrenergic agonist isoproterenol (5 and 10 micrograms) increased the diuretic action of ethanol. On the other hand dopamine (4-20 micrograms) and serotonin (8 and 20 micrograms) had no effect on ethanol diuresis when given intraventricularly. These results indicate that the diuretic action of ethanol involves noradrenergic mechanisms.

The role of cholinergic neurons in the motor depressant effects of ethanol was examined. Choline chloride pretreatment (30–90 mg/kg i.p.) potentiated the hypomotility produced by 2 g/kg of ethanol. Physostigmine pretreatment (0.2 mg/kg, i.p.) also enhanced the motor depression produced by ethanol. Conversely, in animals pretreated with scopolamine (0.25 and 0.5 mg/kg) the depressant effect of ethanol was less. The potentiation produced by choline was not associated with changes in levels of ethanol in blood. It is concluded that cholinergic neurons are involved in the motor activity changes produced by ethanol. Such a mechanism may operate in conjunction with the dopaminergic neuronal system.