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Sardinia is an Italian island in the Mediterranean characterized by secular isolation and the singular genetic characteristics of its inhabitants. Findings obtained in populations with diverse genetic make-up and cultural background indicate gender differences and/or similarities in drinking characteristics of patients with alcohol use disorder (AUD). Knowledge of these characteristics in AUD patients is useful to improve access to treatments. This paper investigated the drinking characteristics of 66 female and 282 male outpatients with AUD, born from 1937 to 1991, living in Sardinia, and compared their characteristics with those of AUD patients living in other countries. Most Sardinian patients were men, approximately 3 years younger than women, women consumed lower amounts of alcohol than men but did not differ from men in the severity of AUD. Men were more often single than women, while a higher proportion of women reported that their mother or spouse was affected by AUD. Anxiety and depression were more prevalent among women while a higher proportion of men were affected by substance use disorders. Women were older than men at the age of first drink, regular drinking, and onset of AUD, and progressed faster than men from regular use to AUD onset. Women did not differ from men in age at first request for care, and in the lapse from AUD onset to first request for care. Women and men waited for more than 8 and 9 years, respectively, before receiving medical treatment. Gender differences progressively decreased among younger patients. Although the scarce number of women in some cohorts limits the strength of these findings, drinking characteristics of Sardinian patients did not vary significantly from those of AUD patients living in other countries. These results suggest that the number of Sardinian women with AUD is increasing and services for treatment of AUD should (a) consider women’s specific needs, and (b) realize effective policies to reduce latency prior to accessing medical treatment for both men and women with AUD.

This paper summarizes the several lines of experimental evidence demonstrating the ability of the prototypic GABAB receptor agonist, baclofen, to suppress multiple alcohol-related behaviors in laboratory rodents and non-human primates exposed to validated experimental models of alcohol use disorder (AUD). Specifically, treatment with baclofen has repeatedly been reported to suppress alcohol-induced locomotor stimulation, alcohol drinking (including binge- and relapse-like drinking), operant oral alcohol self-administration, alcohol seeking, and reinstatement of alcohol seeking in rats and mice. Treatment with baclofen also reduced operant oral alcohol self-administration in baboons. Several of these effects appear to be mediated by GABAB receptors located in the ventral tegmental area. The often observed co-occurrence of “desired” pharmacological effects and “unwanted” sedative effects represents the major drawback of the preclinical, anti-alcohol profile of baclofen. Collectively, these data underline the role of the GABAB receptor in the mediation of several alcohol-related behaviors. These data possess remarkable translational value, as most of the above effects of baclofen have ultimately been reproduced in AUD patients.

Recent lines of experimental evidence have indicated that saikosaponin A (SSA)—a bioactive ingredient of the medicinal plant, Bupleurum falcatum L.—potently and effectively reduced operant self-administration of chocolate and reinstatement of chocolate-seeking behavior in rats. The present study was designed to assess whether the protective properties of SSA on addictive-like, food-related behaviors generalize to a rat model of overeating of palatable food. To this end, rats were habituated to feed on a standard rat chow for 3 h/day; every 4 days, the 3-h chow-feeding session was followed by a 1-h availability of highly palatable, calorie-rich Danish butter cookies or Oreo chocolate cookies. Even though fed, rats consumed large amounts of cookies; intake of calories from cookies (consumed in 1 h) was even larger than that of calories from chow (consumed in 3 h). SSA (0, 0.25, 0.5, and 1 mg/kg, i.p.) was administered 10 min before cookie presentation. Treatment with SSA resulted in a dose-related decrease in intake of both butter and chocolate cookies. Administration of the cannabinoid CB1 receptor antagonist/inverse agonist, rimonabant (0, 0.3, 1, and 3 mg/kg, i.p.; tested as reference compound), produced a similar reduction in intake of butter cookies. These results (a) contribute to the set-up and validation of a rat model of overeating, characterized by the intake of large amounts of unnecessary calories and (b) provide an additional piece of evidence to the anorectic profile of SSA in rats.

Previous evidence has suggested that treatment with a standardized dry extract of Phaseolus vulgaris reduced intake and operant self-administration of highly palatable foods and fluids in rats and mice. The present study was designed to assess whether such extract was also effective in reducing seeking behavior for a highly hedonic chocolate-flavored beverage, using a reinstatement procedure adopted from the drug addiction research field and modeling relapse behavior. Rats were initially trained to lever-respond for the chocolate-flavored beverage under the Fixed Ratio (FR) 10 (FR10) schedule of reinforcement. Subsequently, rats were exposed to an extinction responding phase, during which lever-responding – being unreinforced – diminished progressively up to extinction. Lever-responding was then powerfully reinstated by the non-contingent presentation of a complex of gustatory, olfactory, auditory, and visual stimuli previously associated to the availability of the chocolate-flavored beverage. Acute, intragastric administration of P. vulgaris dry extract (100 and 500 mg/kg) reduced lever-responding by 40-45%, in comparison to vehicle condition. These results indicate the ability of P. vulgaris dry extract to reduce seeking behavior for a highly palatable nourishment in an experimental model of relapse into disordered eating of palatable foods. The unavailability of the chocolate-flavored beverage in the reinstatement session tends to exclude that the observed effect of the P. vulgaris dry extract was secondary to any inhibition of carbohydrate metabolism; conversely, it is the likely consequence on a central action on the rewarding and hedonic properties of food.

Recent studies demonstrated that treatment with saikosaponin A (SSA) - an active ingredient of the medicinal herb, Bupleurum falcatum L. - selectively suppressed, likely via a GABAB receptor-mediated mechanism, intravenous self-administration of morphine and cocaine in rats [Yoon et al., 2012; 2013]. The present study was designed to investigate whether the capacity of SSA to suppress morphine and cocaine self-administration extends to oral alcohol self-administration. To this end, selectively bred Sardinian alcohol-preferring (sP) rats were trained to lever-respond on a Fixed Ratio (FR) 4 (FR4) schedule of reinforcement for alcohol (15%, v/v) in daily 30-min sessions. Once responding had stabilized, rats were tested under the FR4 (measure of alcohol reinforcing properties) and Progressive Ratio (PR; measure of alcohol motivational properties) schedules of reinforcement. The possible involvement of the GABAB receptor system was investigated testing the effect of (a) pretreatment with the GABAB receptor antagonist, SCH50911, and (b) combined treatment with the positive allosteric modulator of the GABAB receptor, GS39783. Treatment with SSA (0, 0.25, 0.5, and 1mg/kg, i.p.) markedly reduced lever-responding for alcohol, amount of self-administered alcohol, and breakpoint for alcohol (defined as the lowest response requirement not achieved in the PR experiment). Pretreatment with 2mg/kg SCH50911 (i.p.) resulted in a partial blockade of the reducing effect of 0.5mg/kg SSA on lever-responding for alcohol and amount of self-administered alcohol. Combination of per se ineffective doses of GS39783 (5mg/kg, i.g.) and SSA (0.1mg/kg, i.p.) reduced lever-responding for alcohol and amount of self-administered alcohol. These results (a) extend to alcohol self-administration the capacity of SSA to suppress morphine and cocaine self-administration in rats and (b) suggest that the GABAB receptor system is likely part of the neural substrate underlying the reducing effect of SSA on alcohol self-administration.

The endogenous brain constituent, γ-hydroxybutyric acid (GHB), as well as its prodrug, γ-butyrolactone (GBL), have recently gained interest in the drug addiction field due to their abuse potential and fatalities caused by overdose. It is known that GHB has two sites of actions: the γ-aminobutyric acidB(GABAB) receptor and a specific-GHB binding site. The present study was designed to extend to GBL the investigations on the contribution of the GABABreceptor and the specific-GHB binding site to its in vivo effects. To this aim, DBA mice were pretreated either with GABAB-receptor antagonists, (3-aminopropyl)(diethoxymethyl)phosphinic acid (CGP 35348) and (2S)(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), or a putative antagonist of the specific-GHB binding site, 6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylideneacetic acid (NCS-382), prior to the administration of doses of GBL that induced hypothermia, motor-incoordination (measured as motor-impairment at the Rota-Rod task), and sedation/hypnosis. The capability of SCH 50911 and NCS-382 to protect against GBL-induced lethality was also investigated. Pretreatment with either GABAB-receptor antagonist completely prevented GBL-induced hypothermia, motor-incoordination, and sedation /hypnosis. SCH 50911 also provided complete protection against GBL-associated lethality. Vice versa, NCS-382 failed to exert any antagonistic or protective effect. These results suggest that the in vivo GBL effects tested in the present study are mediated by activation of the GABABreceptor. Keywords:: γ-butyrolactone (GBL), γ-hydroxybutyric acid (GHB), γ-aminobutyric acidB(GABAB)-receptor antagonist (CGP 35348, SCH 50911), antagonist of the specific-GHB binding site, NCS-382

Recent research found that exposure of selectively bred, Sardinian alcohol-preferring (sP) rats to multiple alcohol concentrations (10%, 20%, and 30%, v/v), under the 4-bottle “alcohol vs. water” choice regimen, in daily 1-h drinking sessions with an unpredictable time schedule, promoted high intakes of alcohol (≥2 g/kg) when the drinking session occurred over the final hours of the dark phase of the light/dark cycle. The present study was aimed at investigating whether these high intakes of alcohol (a) were associated with alterations in rats’ emotional state (Experiment 1) and (b) were pharmacologically manipulable (Experiment 2). In both experiments, over a period of 12 days, sP rats were initially exposed daily to a1-h drinking session performed during the 12-h duration of the dark phase; time of alcohol exposure was changed each day and was unpredictable to rats. The day after this 12-day drinking phase, rats were (a) exposed to the Social Interaction (SI) test at the 1st or 12th hour of the dark phase with no alcohol available (Experiment 1) or (b) treated acutely with the positive allosteric modulator of the GABAB receptor, GS39783 (0, 25, 50, and 100 mg/kg, intragastrically [i.g.]), and exposed to a drinking session at the 12th hour of the dark phase (Experiment 2). In Experiment 1, rats exposed to the SI test during the 12th hour spent approximately 35% less time in “social” behaviors than rats exposed to the SI test during the 1st hour. No difference in “social” behaviors was observed between alcohol-naive sP rats exposed to the SI test at the 1st and 12th hour. In Experiment 2, all doses of GS39783 selectively reduced alcohol intake. These results suggest that (a) expectation of alcohol availability likely exacerbated the anxiety-like state of sP rats and (b) the GABAB receptor is part of the neural substrate underlying these exceptionally high intakes of alcohol in sP rats.

Endocannabinoids act as neuroprotective molecules promptly released in response to pathological stimuli. Hence, they may represent one component of protection and/or repair mechanisms mobilized by dopamine (DA) neurons under ischemia. Here, we show that the endocannabinoid 2-arachidonoyl-glycerol (2-AG) plays a key role in protecting DA neurons from ischemia-induced altered spontaneous activity both in vitro and in vivo. Accordingly, neuroprotection can be elicited through moderate cannabinoid receptor type-1 (CB1) activation. Conversely, blockade of endocannabinoid actions through CB1 receptor antagonism worsens the outcome of transient ischemia on DA neuronal activity. These findings indicate that 2-AG mediates neuroprotective actions by delaying damage and/or restoring function of DA cells through activation of presynaptic CB1 receptors. Lastly, they point to CB1 receptors as valuable targets in protection of DA neurons against ischemic injury and emphasize the need for a better understanding of endocannabinoid actions in the fine control of DA transmission.

The dried roots of Salvia miltiorrhiza are highly valued in Chinese folk medicine for use in the prevention and treatment of a series of ailments. Previous studies have demonstrated that administration of standardized extracts of S. miltiorrhiza selectively reduced excessive alcohol drinking and relapse-like drinking in selectively bred Sardinian alcohol-preferring (sP) rats. The present study was designed to extend these findings on the "anti-alcohol" properties of S. miltiorrhiza extracts to operant procedures of oral alcohol self-administration. Two independent groups of sP rats were trained to lever-respond on an FR4 schedule of reinforcement for alcohol (15%, v/v) or sucrose (1–3%, w/v) in daily 30 min sessions. Once responding had stabilized, rats were tested under the fixed ratio 4 (FR4) schedule of reinforcement (index of alcohol reinforcing properties) and the progressive ratio (PR) schedule of reinforcement (index of alcohol motivational properties). Treatment with S. miltiorrhiza extract (0, 50, 100, and 200 mg/kg, intragastrically [i.g.]) markedly reduced lever responding for alcohol, amount of self-administered alcohol, and breakpoint for alcohol (defined as the lowest response requirement not achieved in the PR experiment). No dose of S. miltiorrhiza extract altered any parameter of sucrose self-administration. These results a) demonstrate that treatment with S. miltiorrhiza extract selectively reduced the reinforcing and motivational properties of alcohol in sP rats and b) extend to operant procedures of alcohol self-administration previous data on the "anti-alcohol" effects of S. miltiorrhiza extracts. These data strengthen the notion that novel pharmacological approaches for treatment of alcohol use disorders may stem from natural substances.

The stress-response corticotropin-releasing factor (CRF) and dynorphin systems are critically involved in alcohol drinking and “anxiety” ”-related behaviors. Selectively bred Sardinian alcohol-preferring (sP) rats display high inherent “anxiety”-related behaviors, in comparison with their alcohol-non preferring counterpart (sNP rats). The present study was undertaken to investigate: (1) if there were genetically determined differences in basal gene expression levels of CRF, CRF-R1, preprodynorphin (ppDyn) and kappa opioid receptor (KOP-r) between sP and sNP rats; specifically, mRNA levels of the above genes were measured in the central amygdala (CeA), hypothalamus and other stress responsive and mesolimbic regions of alcohol-naive sP and sNP rats; and (2) if the above mRNA levels were altered by voluntary alcohol drinking in sP rats exposed to the standard, homecage 2-bottle “alcohol vs water” choice regimen 24 hours/day for 17 days. Higher basal CRF mRNA levels were found only in CeA of alcohol-naive sP rats, compared with sNP rats; these levels were decreased after alcohol consumption. In contrast, ppDyn mRNA levels in CeA of sP rats were increased by alcohol consumption, but with no basal difference from sNP rats. Although higher basal ppDyn mRNA levels were found in hypothalamus of sP rats, compared with sNP rats, there was no alteration after alcohol drinking in sP rats. No difference for the above mRNA levels was observed in other regions, including nucleus accumbens shell or core, caudate-putamen, ventral tegmental area and medial/basolateral amygdala, between the two rat lines before or after alcohol consumption. Our results demonstrate the existence of genetically determined high basal CRF mRNA levels in CeA of sP rats. Alcohol consumption decreased CeA CRF mRNA levels with parallel increases in CeA ppDyn mRNA levels.

Background: It has been reported that baclofen, a drug used in the treatment of spasticity, reduces the severity of withdrawal symptoms and substance use disorders (SUDs) for some psychoactive drugs. Aims and Methods: To evaluate the effectiveness and safety of baclofen in the treatment of withdrawal syndrome and/or SUDs, providing (1) an outline of its pharmacological features; (2) a summary of studies that have suggested its possible effectiveness in the treatment of SUDs, and (3) a review of randomized, controlled trials (RCTs) on baclofen and SUDs. Results: Baclofen tolerability is generally considered to be good. Eleven RCTs investigated its effectiveness in the treatment of SUDs. Of these, 5 RCTs found that baclofen is effective, 5 RCTs found that it is ineffective and the results of 1 RCT were not appreciable because it did not achieve the preplanned level of participation. Conclusions: The number of RCTs on baclofen and SUDs is still low, and their results are divergent. Further RCTs should be undertaken, particularly with higher doses of baclofen. Its administration may be suggested in patients who fail to respond to other approved drugs or who are affected by liver disease that prevents their administration, or in patients affected by SUDs for which no approved drugs are available. Treatment should be conducted under strict medical supervision.

The potential efficacy of GABA(B) receptor agonists in the treatment of pain, drug addiction, epilepsy, cognitive dysfunctions, and anxiety disorders is supported by extensive preclinical and clinical evidence. However, the numerous side effects produced by the GABA(B) receptor agonist baclofen considerably limit the therapeutic use of this compound. The identification of positive allosteric modulators (PAMs) of the GABA(B) receptor may constitute a novel approach in the pharmacological manipulation of the GABA(B) receptor, leading to fewer side effects. The present study reports the identification of two novel compounds, methyl 2-(1-adamantanecarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate (COR627) and methyl 2-(cyclohexanecarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate (COR628), which act as GABA(B) PAMs in 1) rat cortical membranes and 2) in vivo assay. Both compounds potentiated GABA- and baclofen-stimulated guanosine 5'-O-(3-[(35)S]thio)-triphosphate binding to native GABA(B) receptors, while producing no effect when given alone. GABA concentration-response curves in the presence of fixed concentrations of COR627 and COR628 revealed an increase of potency of GABA rather than its maximal efficacy. In radioligand binding experiments [displacement of the GABA(B) receptor antagonist, 3-N-[1-((S)-3,4dichlorophenyl)-ethylaminol]-2-(S)hydroxypropyl cyclo-hexylmethyl phosphinic acid ([(3)H]CGP54626)], both COR627 and COR628 increased the affinity of high- and low-affinity binding sites for GABA, producing no effect when administered alone up to a concentration of 1 mM. In vivo experiments indicated that pretreatment with per se ineffective doses of COR627 and COR628 potentiated the sedative/hypnotic effect of baclofen. In conclusion, COR627 and COR628 may represent two additional tools for use in investigating the roles and functions of positive allosteric modulatory binding sites of the GABA(B) receptor.

Recent studies demonstrated that activation of the GABA(B) receptor, either by means of orthosteric agonists or positive allosteric modulators (PAMs), inhibited different nicotine-related behaviors, including intravenous self-administration and conditioned place preference, in rodents. The present study investigated whether the anti-nicotine effects of the GABA(B) receptor agonist, baclofen, and GABA(B) PAMs, CGP7930, and GS39783, extend to nicotine stimulant effects. To this end, CD1 mice were initially treated with baclofen (0, 1.25, and 2.5 mg/kg, i.p.), CGP7930 (0, 25, and 50 mg/kg, i.g.), or GS39783 (0, 25, and 50 mg/kg, i.g.), then treated with nicotine (0 and 0.05 mg/kg, s.c.), and finally exposed to an automated apparatus for recording of locomotor activity. Pretreatment with doses of baclofen, CGP7930, or GS39783 that did not alter locomotor activity when given with nicotine vehicle fully prevented hyperlocomotion induced by 0.05 mg/kg nicotine. These data extend to nicotine stimulant effects the capacity of baclofen and GABA(B) PAMs to block the reinforcing, motivational, and rewarding properties of nicotine. These data strengthen the hypothesis that activation of the GABA(B) receptor may represent a potentially useful, anti-smoking therapeutic strategy.

The endocannabinoids anandamide and 2-arachidonoyglycerol (2-AG) may contribute to the regulation of mood and emotion. In this study, we investigated the impact of the endocannabinoid transport inhibitor AM404 on three rat models of anxiety: elevated plus maze, defensive withdrawal and separation-induced ultrasonic vocalizations. AM404 (1-5 mg kg-1, intraperitoneal (i.p.)) exerted dose-dependent anxiolytic-like effects in the three models. These behavioral effects were associated with increased levels of anandamide, but not 2-AG, in the prefrontal cortex and were prevented by the CB1cannabinoid antagonist rimonabant (SR141716A), suggesting that they were dependent on anandamide-mediated activation of CB1cannabinoid receptors. We also evaluated whether AM404 might influence motivation (in the conditioned place preference (CPP) test), sensory reactivity (acoustic startle reflex) and sensorimotor gating (prepulse inhibition (PPI) of the startle reflex). In the CPP test, AM404 (1.25-10 mg kg-1, i.p.) elicited rewarding effects in rats housed under enriched conditions, but not in rats kept in standard cages. Moreover, AM404 did not alter reactivity to sensory stimuli or cause overt perceptual distortion, as suggested by its lack of effect on startle or PPI of startle. These results support a role of anandamide in the regulation of emotion and point to the anandamide transport system as a potential target for anxiolytic drugs. © 2006 Nature Publishing Group All rights reserved.

Extracellular single-unit recordings of nigral dopamine (DA) neurons were obtained from conscious rats habituated to having their body suspended in a cloth jacket and their head immobilized in the stereotaxic frame by means of a "restraining platform" permanently fixed to the skull. The electrophysiological characteristics of DA neurons from head-restrained rats and their responses to apomorphine and haloperidol were compared with single-unit recordings obtained from rats lightly and deeply anesthetized with chloral hydrate and from mesencephalic slices. Head-restrained rats showed a higher number of spontaneously active DA neurons and a higher percentage of bursting neurons than lightly and deeply anesthetized rats. Indeed, bursting activity was rare in deeply anesthetized rats and was totally absent in slices. Haloperidol was more potent and effective in stimulating the firing rate and bursting activity in head-restrained than in lightly anesthetized rats, while it was virtually ineffective in deeply anesthetized rats and totally ineffective in slices. On the other hand, DA neurons in head-restrained rats showed the same average firing rate as DA neurons in lightly and deeply anesthetized rats and in slices. The potency of apomorphine in inhibiting the firing rate, and that of haloperidol in reversing apomorphine effect, did not vary among the different in vivo preparations. The results suggest that chloral hydrate anesthesia blunts or suppresses not only the excitatory inputs which normally sustain the number of spontaneously active DA neurons and their bursting activity, but also the feedback excitation of DA neurons following haloperidol-induced D(2) receptor blockade. On the other hand, chloral hydrate anesthesia modifies neither D(2) autoreceptor sensitivity to apomorphine and haloperidol nor the automatic genesis of action potentials. The head-restrained rat appears to be an important model for studies into the pharmacology and physiology of DA neurons.

To investigate the possible long-term consequences of gestational exposure to cannabinoids on cognitive functions, pregnant rats were administered with the CB1 receptor agonist WIN 55,212-2 (WIN), at a dose (0.5 mg/kg) that causes neither malformations nor overt signs of toxicity. Prenatal WIN exposure induced a disruption of memory retention in 40- and 80-day-old offspring subjected to a passive avoidance task. A hyperactive behavior at the ages of 12 and 40 days was also found. The memory impairment caused by the gestational exposure to WIN was correlated with alterations of hippocampal long-term potentiation (LTP) and glutamate release. LTP induced in CA3–CA1 synapses decayed faster in brain slices of rats born from WIN-treated dams, whereas posttetanic and short-term potentiation were similar to the control group. In line with LTP shortening, in vivo microdialysis showed a significant decrease in basal and K + -evoked extracellular glutamate levels in the hippocampus of juvenile and adult rats born from WIN-treated dams. A similar reduction in glutamate outflow was also observed in primary cell cultures of hippocampus obtained from pups born from mothers exposed to WIN. The decrease in hippocampal glutamate outflow appears to be the cause of LTP disruption, which in turn might underlie, at least in part, the long-lasting impairment of cognitive functions caused by the gestational exposure to this cannabinoid agonist. These findings could provide an explanation of cognitive alterations observed in children born from women who use marijuana during pregnancy.

Recent preclinical and clinical studies have indicated a possible involvement of the genes encoding for the GABA(A) receptor subunits alpha6, beta2, alpha1 and gamma2 in the genetic susceptibility to alcohol abuse. We have recently found an (R) to (Q) mutation in codon 100 of the alpha6 GABA(A) subunit, that segregated in a rat line selectively bred for its voluntary ethanol aversion, Sardinian alcohol nonpreferring (sNP), but not in their Sardinian alcohol preferring (sP) counterpart, selected for its ethanol preference. In the present study the molecular composition of other GABA(A) subunits (beta2, alpha1 and gamma2) were analyzed in order to further investigate the involvement of the GABA(A) receptors in the genetic predisposition to voluntary alcohol intake. Automated sequencing analysis indicated the presence of six new silent substitutions (289 T-->C in the beta2 gene; 115 G-->A in the alpha1 gene; 157 G-->A, 174 C-->T, 347 A-->G and 385 A-->T in the gamma2 gene), in sNP but not in sP rats. These polymorphisms were linked to the alpha6 R100Q mutation previously described in sNP rats. The strict association between the alpha6 point mutation and the new polymorphisms found in the beta2, alpha1 and gamma2 genes, demonstrate that such genes belong to the same cluster and are inherited together in the rat. These results sustain the synteny for these clusters between the rodent and human genomes, and suggest that mutated GABA(A) beta2, alpha6, alpha1 and gamma2 subunit genes might contribute to the expression of an ethanol nonpreferring phenotype in a rat line that voluntarily avoids alcoholic solutions.

OBJECTIVE: Previous reports have shown that the Delta(9)-tetrahydrocannabinol (Delta(9)TCH), the major psychoactive cannabinoid components of marijuana, is able [corrected] to inhibit thyroid hormonal activity. The aim of this study was to characterize the CB1 functional expression in the rat thyroid by a multi-methods approach. METHODS AND RESULTS: RT-PCR was used to detect the mRNA expression of the CB1 cannabinoid receptor (17.8+/-4.0% of the normalizing reference gene beta(2) microglobulin), as well as the expression of the endocannabinoid hydrolyzing enzyme, fatty acid amide hydrolase (46.9+/-4.3% of beta(2) microglobulin), in the rat thyroid gland. The CB1-encoded protein was detected in its glycosylated form (63 kDa) by Western blot, employing a polyclonal antibody, while CB1 immunohistochemical localization showed an intracellular positive staining in both follicular and parafollicular cells. In addition, a 30% decrease in serum levels of both 3,5,3' tri-iodothyronine (T(3)) and thyroxine (T(4)) was detected 4 h after the administration of the synthetic cannabinoid receptor agonist, WIN 55,212-2 (10 mg/kg i.p.). These effects were antagonized by pretreatment with the CB1 antagonist SR 141716A (3 mg/kg i.p.); thyrotrophin levels were unaffected by both treatments. CONCLUSION: These data indicate that functional CB1 receptors which are able to modulate the release of T(3) and T(4) are expressed in the rat thyroid, and suggest a possible role of cannabinoids in the regulation of rat thyroid hormonal activity.

The effects on rat serum prolactin level of the two isomers constituting the racemic form of amisulpride were compared. (S-)-amisulpride induced hyperprolactinemia at lower doses (ED(50) = 0.09 +/- 0.01 mg/kg) than racemic- (ED(50) = 0.24 +/- 0.03 mg/kg) and (R+)-amisulpride (ED(50) = 4.13 +/- 0.05 mg/kg), in accord with their affinities for pituitary dopamine D(2) receptor (K(i) = 3.8 +/- 0.2, 6.4 +/- 0.2 and 143.3 +/- 2.3 nM, respectively). At doses twice the ED(50), (S-)-amisulpride produced a maximal increase in prolactin level similar to that of the racemic form (403 +/- 21% and 425 +/- 15%, respectively), but higher than that of (R+)-amisulpride (198 +/- 8%). These results suggest that the hyperprolactinemia induced by the racemic-amisulpride is mostly due to its (S-)-isomer.

The substituted benzamide amisulpride is currently administered in its racemic form. In the present study, the biochemical and cataleptogenic profiles of the two enantiomers (R+ and S-) were compared with those of the racemic mixture. Displacement binding studies showed that the (S-)-isomer possesses an higher affinity for dopamine D2-like receptor (K(i) 5.2+/-0.4 nM) compared to (R+)-amisulpride (K(i) 244+/-12 nM) and to (RS)-amisulpride (K(i) 9.8+/-0.8 nM). In contrast, (S-)-amisulpride binds the alpha(2)-receptor with an affinity (K(i) 1528+/-45 nM) lower than that of the (R+)-isomer (K(i) 375+/-34 nM) and of (RS)-amisulpride (K(i) 783+/-27 nM). The bar test was used to evaluate the catalepsy induced by each drug. (RS)-amisulpride induced catalepsy only at very high doses (>100 mg/kg, s.c.) whereas, (S-)-amisulpride produced a catalepsy at a lower dose (30 mg/kg, s.c.) and (R+)-amisulpride did not produce any catalepsy up to the dose of 75 mg/kg. Interestingly, (R+)-amisulpride reduced the catalepsy induced by (S-)-amisulpride (50 mg/kg, s.c.) or haloperidol (0.3 mg/kg, s.c.), at the doses of 50 or 30 mg/kg, respectively. These results indicate that the weak cataleptic properties of (RS)-amisulpride might partially rely on its (R+)-isomer and provide a further explanation for the atypical properties of amisulpride as an antipsychotic.

In the present work, we investigated if an impairment of dopaminergic neurons after subchronic haloperidol treatment might be a possible physiopathologic substrate of the "early onset" vacuous chewing movements (VCMs) in rats. For this purpose, different antipsychotics were used to analyse a possible relationship between VCMs development and morphological alterations of tyrosine-hydroxylase-immunostained (TH-IM) neurons. Rats treated twice a day with haloperidol displayed a significant increase of VCMs that was both time- (2-4 weeks) and dose (0.1-1 mg/kg) dependent. Immunocytochemical analysis showed a shrinkage of TH-IM cell bodies in substantia nigra pars compacta and reticulata and a reduction of TH-immunostaining in the striatum of haloperidol treated rats with the arising of VCMs. No differences were observed in TH-IM neurons of ventral tegmental area and nucleus accumbens vs. control rats. The atypical antipsychotics risperidone (2 mg/kg, twice a day), amisulpride (20 mg/kg, twice a day) and clozapine (10 mg/kg, twice a day) did not produce any nigro-striatal morphological changes or VCMs. TH-IM nigro-striatal neuron morphological alterations and VCMs were still present after three days of withdrawal in rats treated for four weeks with haloperidol (1 mg/kg). Both the main morphological changes and the behavioural correlate disappeared after three weeks of withdrawal. These results suggest that haloperidol induces a morphological impairment of the dopaminergic nigro-striatal neurons which is directly associated with the arising, permanency and disappearance of VCMs in rats.

Prolactin blood level and apomorphine-induced yawning were studied in rats treated with the substituted benzamide amisulpride in association with bromocriptine or carmoxirole; two dopamine D 2 receptor agonists with high or low propensity to cross the brain–blood barrier, respectively. Administration of amisulpride produced a maximum increase in rat serum prolactin level (315±18%) vs. vehicle-treated animals (ED 50 =0.25±0.017 mg/kg, s.c.). The concurrent administration of carmoxirole or bromocriptine completely reversed the hyperprolactinemia induced by amisulpride (0.5 mg/kg, s.c.) (ID 50 =14.9±0.8 mg/kg and 0.81±0.03 mg/kg, respectively). Carmoxirole (15 mg/kg, i.p.) did not affect yawning induced by apomorphine (0.08 mg/kg, s.c.) nor amisulpride (0.5 mg/kg, s.c.) blockade of apomorphine-induced yawning. Conversely, a significant increase in the number of yawns was observed when bromocriptine (0.8 mg/kg, i.p.) was associated with apomorphine in the absence or presence of amisulpride. These results suggested that a peripheral dopamine D 2 receptor agonists could be a useful tool in alleviating amisulpride-induced hyperprolactinemia without possibly affecting its central effect.

The mesolimbic dopamine (DA) system has long been known to be involved in reward behaviors. As with other substances of abuse, it has been extensively reported that ethanol influences the dopaminergic system. The present study examined whether selectively bred Sardinian-alcohol-preferring (sP) and Sardinian alcohol non-preferring rats (sNP), differ in the DA innervation in structures of the forebrain that are related to rewarding behaviors. To this aim, we performed an immunohistochemistry study with an antibody raised against tyrosine hydroxylase (TH), the rate-limited step enzyme in the biosynthesis of monoamines. The TH-positive innervation density was found to be significantly lower in the cingulate cortex and in the shell of the nucleus accumbens of the sP when compared with the sNP and unselected Wistar rats. These anatomical structures both cluster in the medial aspect of the mesolimbic system. No differences in other major DA brain regions, such as the nigro-striatal pathway were found. The analysis of cell-body area revealed no differences between sP, sNP and Wistar rats in the ventral tegmental area and substantia nigra (pars compacta and reticulata) and the density of the TH-positive fibers was not different in the caudate-putamen. These results indicate a selective reduction of terminal innervation in the medial portion of the mesocorticolimbic DA system in sP rats and suggest that the latter may consume larger amounts of ethanol, when compared with sNP rats, to compensate for the deficiency of dopamine to produce an adequate level of reward.

Rationale: A large body of evidence indicates high comorbidity between depression and alcohol abuse. The self-medication hypothesis proposes that depressed subjects may abuse ethanol because it reduces the symptoms of depression. The present study evaluated whether ethanol may exert an antidepressant-like action in genetically selected alcohol-preferring rats, either Sardinian alcohol-preferring (sP) or Marchigian Sardinian alcohol-preferring (msP) rats, and for comparison in Sardinian alcohol-non-preferring (sNP) rats. Methods: The forced swimming test (FST) was used to evaluate the antidepressant-like action of ethanol; in this test the effect of ethanol ingestion on the immobility time was determined. Results: Ethanol-naive sP rats exhibited a longer period of immobility in comparison to sNP rats. Both in ethanol-naive sP and msP rats, voluntary ethanol drinking reduced the immobility time. A similar effect was obtained when repeated (five or nine) intragastric administrations of 0.7 g/kg ethanol were given during the 24 h prior to the test in msP and in sP, but not in sNP rats. Desipramine, like ethanol, sharply reduced immobility at doses of 5 or 20 mg/kg, given 3 times in the 24 h before the test in msP rats. The reduced immobility induced by ethanol in msP rats was apparently not the consequence of a general motor activation, because 9 IG administrations of ethanol, 0.7 g/kg, failed to alter locomotor activity in the open field test. Moreover, blood alcohol levels and rectal temperature of msP, sP and sNP after IG ethanol administration were not statistically different. Conclusions: The present results provide evidence for an antidepressant-like action of ethanol in sP and msP rats and suggest that this action may contribute to sustain their high ethanol drinking.

The mesolimbic dopamine system has recently been implicated in the long-term aversive consequences of withdrawal from major drugs of abuse. In the present study we sought to determine whether mesolimbic dopamine neurons are involved in the neurobiologic mechanisms underlying withdrawal from chronic cannabinoid exposure. Rats were treated chronically with the major psychoactive ingredient of hashish and marijuana, Δ 9 -tetrahydrocannabinol (Δ 9 -THC). Administration of the cannabinoid antagonist SR 141716A precipitated an intense behavioral withdrawal syndrome, whereas abrupt Δ 9 -THC suspension failed to produce overt signs of abstinence. In contrast, both groups showed a reduction in dopamine cells activity as indicated by extracellular single unit recordings from antidromically identified meso-accumbens dopamine neurons. The administration of Δ 9 -THC to spontaneously withdrawn rats restored neuronal activity. Conversely, SR 141716A produced a further decrease of spontaneous activity in cannabinoid-treated although it was ineffective in control rats. These data indicate that withdrawal from chronic cannabinoid administration is associated with reduced dopaminergic transmission in the limbic system, similar to that observed with other addictive drugs; these changes in neuronal plasticity may play a role in drug craving and relapse into drug addiction.

The effect of chronic treatment with antidepressants (ADs) on the behavioral responses to LY 171555, a selective D2 receptor agonist, SKF 38393, a selective D1 receptor agonist, and B-HT 920, a selective DA autoreceptor agonist, was studied in rats. In normal rats small, intermediate and high doses of LY 171555 produced hypomotility, hyperactivity and stereotypies, respectively. Chronic but not acute pretreatment with imipramine (IMI) greatly potentiated the motor stimulant effect of LY 171555, but failed to modify its stereotypic and sedative effect. The potentiation of the motor stimulant effect of LY 171555 was observed also after chronic, but not acute, treatment with desmethylimipramine (DMI), mianserin (MIA) or repeated electroconvulsive shock (ECS). Chronic treatment with IMI failed to modify the effect of SKF 38393 (motor stimulation, grooming and penile erection), but reversed the sedative effect of B-HT 920 into a motor stimulant response. The motor stimulant response to LY 171555 in IMI-pretreated animals was suppressed by l -sulpiride, a D2 antagonist, and by a combination of reserpine with α-methyltyrosine (α-MT), but it was only partially antagonized by high doses of SCH 23390, a selective D1 antagonist. The results indicate that chronic treatment with ADs potentiates the behavioural responses mediated by the stimulation of postsynaptic D2 receptors in the mesolimbic system and suggest that this behavioural supersensitivity is due to enhanced neurotransmission at the D1 receptor level.

Foot-shock produced a more than 2-fold increase in noradrenaline (NA) release from the frontal cortex of freely moving rats. The effect of acute stress was almost completely prevented by the administration of diazepam (5 mg/kg i.p.). Diazepam alone inhibited cortical NA release, the maximal inhibition (-57%) being observed 90 min after the injection. Cortical NA release therefore appears to be a reliable index of central noradrenergic activity in response to stressful conditions.

Dihydropyridine L-type calcium channel antagonist, nimodipine, prevents both the cocaine-induced DA output in the striatum, as measured by brain microdialysis in freely moving rats, and the motor stimulant effect of the drug

Supersensitivity of dopamine (DA) autoreceptors develops soon after acute treatments with baclofen or γ-butyrolactone, two drugs which suppress DA neuronal firing. We have hypothesized that this effect might reflect a condition associated with the low firing rate of DA cells induced by such treatments rather than a long-term adaptive modification of DA receptor sensitivity. In this study we show that the degree of the intravenous apomorphine-induced inhibition of A9-DA neurons is inversely correlated to the basal firing rate of these neurons. When administered after baclofen, apomorphine further reduced DA cell activities in a manner proportional to the predrug firing rate, as in control rats. Since the minute doses of apomorphine which were used are thought to selectively activate DA autoreceptors, our finding may indicate that DA autoreceptor stimulation is more effective when the activity of the DA neurons is low, or it is decreased by drugs such as baclofen.