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Neuropeptide Y (NPY) and Protein Kinase A (PKA) have been implicated in neurobiological responses to ethanol. We have previously reported that mutant mice lacking normal production of the RIIβ subunit of PKA (RIIβ−/− mice) show enhanced sensitivity to the locomotor stimulant effects of ethanol and increased behavioral sensitization relative to littermate wild-type RIIβ+/+ mice. We now report that RIIβ−/− mice also show increased NPY immunoreactivity in the nucleus accumbens (NAc) core and the ventral striatum relative to RIIβ+/+ mice. These observations suggest that elevated NPY signaling in the NAc and/or striatum may contribute to the increased sensitivity to ethanol-induced behavioral sensitization that is characteristic of RIIβ−/− mice. Consistently, NPY−/− mice failed to display ethanol-induced behavioral sensitization that was evident in littermate NPY+/+ mice. To more directly examine the role of NPY in the locomotor stimulant effects of ethanol, we infused a recombinant adeno-associated virus (rAAV) into the region of the NAc core of DBA/2J mice. The rAAV-FIB-NPY13-36 vector expresses and constitutively secretes the NPY fragment NPY13-36 (a selective Y2 receptor agonist) from infected cells in vivo. Mice treated with the rAAV-FIB-NPY13-36 vector exhibited reduced expression of ethanol-induced behavioral sensitization compared to mice treated with a control vector. Taken together, the current data provide the first evidence that NPY signaling in the NAc core and the Y2 receptor modulate ethanol-induced behavioral sensitization.

Adolescence is known to be a time of increased use of alcohol, and this use is the strongest predictor of alcohol dependence in adulthood (Grant, 1998; Grant and Dawson, 1997). Additionally, the dependency course (time between initial use and dependence) is more rapid in adolescents than in adults (Clark et al., 1998). Further, it has been suggested that stress during adolescence is also a contributing factor for the development of alcohol dependence (Arnsten and Shansky, 2004; Enoch, 2006; Wagner, 1993). Studies in adolescent rodents have generated mixed findings regarding the consequences of stress on ethanol consumption (Brunell and Spear, 2005; Chester et al., 2008; Doremus et al., 2005). While these studies have demonstrated that the interactions between stress and ethanol intake during adolescence are likely complex, minimal work has been performed to evaluate how stress impacts ethanol withdrawal-related behaviors (i.e., anxiety). Studies in rodents showed that repeated episodes of ethanol withdrawal lead to increased sensitivity for seizure sensitization or “kindling” following repeated ethanol withdrawals (Becker and Hale, 1993; Kokka et al., 1993; McCown and Breese, 1990). Further investigations demonstrated that other symptoms of withdrawal (i.e., anxiety) could also undergo a kindling-like process in adolescent and adult rodents (Breese et al., 2004; Overstreet et al., 2002; Wills et al., 2009). In these experiments, it was shown that withdrawal from three 5-day cycles of ethanol diet (see Fig. 1A) induced anxiety-like behavior (measured by a reduction in social interaction), which was not produced by withdrawal from 15 continuous days of ethanol exposure (Overstreet et al., 2002; Wills et al., 2009). This anxiety-like behavior only following repeated ethanol withdrawals illustrated that the pattern of ethanol exposure was important in sensitizing anxiety-like behavior (Breese et al., 2005a). Later work set out to determine whether there were sensitivity differences between adolescent and adult rats in the anxiety produced from repeated ethanol withdrawals. While there were no differences between ages in the amount of anxiety (% decrease in SI from controls) 5 hours into withdrawal, there were differences in the duration of this anxiety (length of time present after final withdrawal). In adolescent rats, anxiety-like behavior was present 7 days after the final withdrawal, while in adult rats anxiety had returned to baseline with 2 days. These data indicated increased sensitivity to the effects of repeated withdrawals in adolescent rats. Fig. 1 Procedure for repeated ethanol withdrawal, stress/withdrawal, and CRF/withdrawal paradigms (Panels A–C). (A) In the repeated ethanol withdrawal paradigm, rats are given three 5-day cycles of ethanol diet separated by two 2-day withdrawal period ... Other studies (mainly in adults) have also established an interaction between stress and CRF in the development of this anxiety-like behavior during ethanol withdrawal. Initial work found pretreatment with a CRF1 receptor antagonist during repeated ethanol withdrawals prevented the development of anxiety-like behavior in both adolescent and adult rats (Breese et al., 2004; Knapp et al., 2004; Wills et al., 2009). Additional work in adult rats has shown that two weekly 1-hour restraint stress sessions followed by a single 5-day cycle of ethanol diet (not anxiogenic alone) could sensitize anxiety-like behavior (see Fig. 1B; Breese et al., 2004). Further work in adult rats found that CRF administered intraventricularly also substituted for either withdrawals or stress (see Fig. 1C) to produce anxiety-like behavior (Overstreet et al., 2004a). Because adolescent rats were shown to be more sensitive than adults to the effects of repeated ethanol withdrawals, the present work determined whether adolescent rats were also more sensitive to the effects of stress and CRF on ethanol withdrawal-induced anxiety-like. First, it was evaluated whether stress can substitute for withdrawals (stress/withdrawal paradigm) to produce anxiety-like behavior in adolescent rats, as it has been shown to do in adult rats. Further, it was evaluated whether the duration of this anxiety-like behavior (measured as a reduction in social interaction) following stress/withdrawal differs between adolescents and adults, as this metric revealed a sensitivity differences in the repeated withdrawal paradigm. Additional studies were performed to determine whether CRF substituted for withdrawals or stress to produce anxiety-like behavior in adolescent rats and whether the effective doses were similar to those used in adult rats. Finally, experiments were performed to assess the levels of CRF in stress- and anxiety-responsive nuclei (the central nucleus of the amygdale; CeA and paraventricular nucleus of the hypothalamus; PVN) following stress/withdrawal and repeated withdrawal paradigms in both adolescent and adult rats.

Resting and CO2 stimulated respiration were measured by means of a whole-body plethysmograph in rats lightly anaesthetized with halothane. Rats pretreated neonatally with intracisternal 5,7-dihydroxytryptamine (5,7-DHT) to destruct permanently central serotonergic neurones had significantly lower resting and CO2 stimulated respiratory frequency (RF) and minute volume (VM) than naive rats. In the 5,7-DHT pretreated rats, but not in naive rats, the monoamine oxidase inhibitors clorgyline and pargyline further reduced both resting and CO2 stimulated RF and Vm, whereas 1-deprenyl stimulated respiration. The results provide additional evidence that monoaminergic mechanisms are involved in central modulation of respiration in which activation of a serotonergic neuronal system depresses, and dopaminergic activation stimulates respiration.

Background: The alcohol deprivation effect (ADE) is characterized by transient excessive alcohol consumption upon reinstatement of ethanol following a period of ethanol deprivation. While this phenomenon has been observed in rats using both bottle drinking (consummatory behavior) and operant self-administration (consummatory and appetitive “ethanol-seeking” behavior) procedures, ADE studies in mice have primarily relied on bottle drinking measures. Furthermore, the neurochemical pathways that modulate the ADE are not well understood. Therefore, we determined whether the ADE can be observed in C57BL/6J mice using operant self-administration procedures and if expression of the ADE is modulated by the corticotropin releasing factor-1 (CRF-1) receptor. Methods: C57BL/6J mice were trained in a 2-hour operant self-administration paradigm to lever press for 10% ethanol or water on separate response keys. Between operant sessions, mice had access to ethanol in their homecage. Once stable responding occurred, mice were deprived of ethanol for 4 days and were then retested with ethanol in the operant paradigm for 3 consecutive days. Next, to assess the role of the CRF-1 receptor, mice were given intraperitoneal (i.p.) injection (0, 10, or 20 mg/kg) of the CRF-1 receptor antagonist CP-154,526 30 minutes before ADE testing. Additional experiments assessed (i) ADE responding in which the alternate response lever was inactive, (ii) the effects of CP-154,526 on self-administration of a 1% sucrose solution following 4 days of deprivation, and (iii) ADE responding in which mice did not received i.p. injections throughout the experiment. Results: Mice exhibited a significant increase in postdeprivation lever responding for ethanol with either a water reinforced or inactive alternate lever. Interestingly, i.p. injection of a 10 mg/kg dose of CP-154,526 protected against the ADE while not affecting lever responding for a sucrose solution. Finally, baseline and deprivation-induced increases of ethanol reinforced lever responding were greater in mice not given i.p. injections. Conclusions: The ADE in C57BL/6J mice can be modeled using the operant self-administration paradigm and increased ethanol self-administration associated with the ADE is modulated by CRF-1 receptor signaling.

Rats lesioned with 6-hydroxydopamine (6-OHDA) as neonates exhibit behavioral and neurochemical abnormalities in adulthood that mimic Lesch-Nyhan disease, schizophrenia and other developmental disorders of frontostriatal circuit dysfunction. In these animals, a latent sensitivity to D1 agonists is maximally exposed by repeated administration of dopamine agonists in the post-pubertal period (D1 priming). In neonate-lesioned, adult rats primed with SKF-38393, we found selective, persistent alterations in the morphology of pyramidal neuron apical dendrites in the prelimbic area of the medial prefrontal cortex (mPFC). In these animals, dendrite bundling patterns and the typically straight trajectories of primary dendritic shafts were disrupted, whereas the diameter of higher-order oblique branches was increased. Although not present in neonate-lesioned rats treated with saline, these morphological changes persisted at least 21 days after repeated dosing with SKF-38393, and were not accompanied by markers of neurodegenerative change. A sustained increase in phospho-ERK immunoreactivity in wavy dendritic shafts over the same period suggested a relationship between prolonged ERK phosphorylation and dendritic remodeling in D1-primed rats. In support of this hypothesis, pretreatment with the MEK1/2-ERK1/2 pathway inhibitors PD98059 or SL327, prior to each priming dose of SKF-38393, prevented the morphological changes associated with D1 priming. Together, these findings demonstrate that repeated stimulation of D1 receptors in adulthood interacts with the developmental loss of dopamine to profoundly and persistently modify neuronal signaling and dendrite morphology in the mature prefrontal cortex. Furthermore, sustained elevation of ERK activity in mPFC pyramidal neurons may play a role in guiding these morphological changes in vivo.

Adult rats exhibit increased anxiety-like behavior after exposure to repeated cycles of chronic ethanol and withdrawal. While adolescent rats have differential responses to both acute and chronic ethanol treatments, the potential differences in the effects of repeated withdrawals in this population have yet to be determined.Male adult and adolescent rats received three 5-day cycles of either a 4.5% or 7% ethanol diet (ED) separated by two 2-day withdrawal periods. Five hours into the final withdrawal, rats were tested for social interaction (SI) deficits (an index of anxiety-like behavior) and then assessed for seizure thresholds (audiogenic and bicuculline-induced). Ethanol intake was monitored throughout, and blood ethanol concentrations (BEC) were obtained from a separate group of rats.Adolescent rats have reduced SI during the final withdrawal from either ED and exhibit a greater reduction in SI compared to adult rats when exposed to a 7%ED. Audiogenic seizures were not increased during withdrawal from either ED in adult rats, but adolescent rats that received 7%ED displayed increased seizures. The bicuculline seizure thresholds were decreased in both ages exposed to a 7%ED, but only adolescent rats showed this decreased threshold after 4.5%ED. Ethanol intakes and BECs were higher in adolescent rats compared to similarly treated adults. However, ethanol intakes and BECs were comparable between 4.5%ED-treated adolescent and 7%ED-treated adult rats.Behavioral results from the 7%ED-treated groups suggested that adolescent rats may be more vulnerable to repeated withdrawals from ethanol than adults; however, differences in ethanol intake and BECs may be at least in part responsible. When ethanol intakes and BECs were similar between 4.5%ED-treated adolescent and 7%ED-treated adult rats, behavioral effects were not different. Importantly, these data illustrated that adolescent rats can exhibit anxiety and reduced seizure thresholds following this repeated withdrawal paradigm.

Stress may be a key contributor to the development of ethanol dependence and relapse (Breese et al., 2005; Koob, 2003). Stressful life events, such as those underlying post-traumatic stress disorder, are comorbid with ethanol abuse disorders and human laboratory studies show that stress increases the self-report of craving in abstinent alcoholics (Back et al., 2006; Breslau et al., 2003; Fox et al., 2007). Clinical research implicates stress in the relapse to pathological ethanol use in formerly abstinent alcoholics, perhaps as a means to self-medicate heightened anxiety and negative affect associated with withdrawal and abstinence from alcohol (Brady and Sonne, 1999; Breese et al., 2005; Kushner et al., 1994; Sinha, 2001). Recent investigations show that stress can also impact ethanol consumption in animal models (Chester et al., 2004; Croft et al., 2005; Le et al., 2000; Little et al., 1999; Liu and Weiss, 2002; Sillaber et al., 2002). Various stress paradigms reliably elicit stress-induced increases in ethanol consumption, especially among low ethanol consuming animals (Chester et al., 2004; Croft et al., 2005; Little et al., 1999). For example, selectively bred ethanol non-preferring NP rats exposed to 10 days of restraint stress showed significant and enduring increases in ethanol consumption beginning approximately 2 weeks following the stress procedure, while ethanol preferring P rats showed only transient stress-induced increases in ethanol drinking immediately after the stress procedure (Chester et al., 2004). Additionally, 3 weeks of stress induced by daily saline injections (Little et al., 1999) or 5 consecutive days of social defeat stress (Croft et al., 2005), significantly increased ethanol consumption approximately 2 weeks after the stress procedure among C57BL/10 mice displaying initially low preference for ethanol. An interesting commonality among many animal studies that assess the effects of stress on ethanol intake is that the effects of stress on ethanol drinking are delayed, typically occurring weeks after stress exposure (Chester et al., 2004; Croft et al., 2005; Little et al., 1999). Both ethanol and stress activate the hypothalamic-pituitary-adrenal (HPA) axis by inducing the release of corticotropin-releasing factor (CRF), adrenocorticotropic hormone (ACTH), and glucocorticoids (Brady and Sonne, 1999). The relationship between ethanol and the HPA-axis appears to be bidirectional, as exogenous administration of CRF, ACTH, and glucocorticoids alter ethanol consumption (Bell et al., 1998; O’Callaghan et al., 2002; Thorsell et al., 2005). Given that neurobiological responses to both stress and ethanol exposure involve HPA-axis signaling, it is possible that the neurochemicals and hormones associated with the HPA-axis modulate stress-induced increases of ethanol consumption. One such candidate is CRF, a 41 amino acid polypeptide that integrates both neuroendocrine and behavioral responses to stress (Smith et al., 1998). CRF-containing neurons are expressed throughout the brain, including in regions implicated in neurobiological responses to ethanol such as the bed nucleus of the stria terminalis, the amygdala, and the lateral hypothalamus (Koob, 2003). Of the two G protein-coupled receptors, the CRF1 receptor (CRF1R) appears to be involved with the integrate emotional behavior while the CRF2 receptor (CRF2R) may modulate ingestive behaviors (Koob, 2003; Zorrilla and Koob, 2004; Zorrilla et al., 2004). Corticotropin-releasing factor receptor signaling has been implicated in a variety of neurobiological responses to ethanol. For example, CRF receptor antagonists attenuate the anxiogenic effect of ethanol withdrawal (Breese et al., 2004; Knapp et al., 2004; Overstreet et al., 2004; Rassnick et al., 1993), prevent excessive ethanol self-administration in dependent animals (Funk et al., 2007; Valdez et al., 2002), and block foot shock-induced reinstatement of ethanol-seeking behavior (Liu and Weiss, 2002). The CRF1R also appears to be involved in stress-induced increases in ethanol consumption. Mutant mice lacking normal production of the CRF1R displayed significantly greater ethanol consumption beginning approximately 2 weeks after a social defeat stress procedure, an effect that was not evident in normal wild-type mice. Subsequent exposure to forced swim stress further augmented ethanol consumption in CRF1R knockout mice (Sillaber et al., 2002). While the Sillaber et al. (2002) study provides genetic evidence suggesting a role for the CRF1R in modulating stress-induced increases in ethanol consumption, the goal of the present experiment was to use a pharmacological approach to determine if pretreatment with the selective CRF1R antagonist, CP-154,526, would buffer the effects of stress and thus attenuate the development of stress-induced increases in ethanol intake in BALB/cJ mice. Therefore, we predicted that (1) ethanol consumption would increase among animals with a history of stress exposure and (2) pretreatment with CP-154,526 would attenuate stress-induced increases in ethanol consumption among animals with a history of stress. BALB/cJ mice were chosen because this strain has been shown to have high sensitivity to the effects of stress on both behavioral and neurobiological measures (Crawley et al., 1997) and drinks low levels of ethanol (Belknap et al., 1993). We also assessed the effects of stress exposure on ethanol consumption by C57BL/6N mice, a strain that voluntarily consumes high amounts of ethanol (Belknap et al., 1993). Here we show that 5 consecutive days of exposure to a 5-minute forced swim stress procedure caused significant and delayed increases in voluntary ethanol consumption in BALB/cJ mice, an effect which was attenuated by pretreatments with the CRF1R antagonist before each stress session. On the other hand, stress exposure did not alter ethanol intake by C57BL/6N mice.

This article represents the proceedings of a symposium at the 2004 annual meeting of the International Society for Biomedical Research on Alcoholism in Heidelberg, Germany. The symposium was organized by Zachary A. Rodd and Giancarlo Colombo. The presentations were (1) Pharmacological reversal of cycled withdrawal-sensitized or stress-sensitized withdrawal anxiety and enhanced ethanol drinking, by Darin J. Knapp and George R. Breese, (2) Alcohol craving and relapse in rats genetically selected for high alcohol preference, by Zachary A. Rodd and Richard L. Bell, (3) Exposure to stress increases dopaminergic burst firing in awake rats, by Kristin Anstrom and Donald J. Woodward, (4) Involvement of cannabinoid CB1 and GABAB receptors in the control of relapse-like drinking in alcohol-preferring Sardinian alcohol-preferring rats by Giancarlo Colombo and Salvatore Serra, and (5) Stress-induced ethanol drinking in CB1−/−, POMC, and PENK knockout mice, by Idiko Racz and Andreas Zimmer.

THE MELANOCORTIN (MC) system is composed of peptides that are cleaved from the polypeptide precursor proopiomelanocortin (POMC). Central MC peptides are produced by neurons within the hypothalamic arcuate nucleus and the medulla (Dores et al., 1986; Jacobowitz and O’Donohue, 1978; O’Donohue and Dorsa, 1982). These peptides include adrenocorticotropic hormone, α-melanocyte–stimulating hormone (α-MSH), β-MSH, and γ-MSH (Hadley and Haskell-Luevano, 1999). Genetic and pharmacological evidence reveals that MC receptor (MCR) signaling is involved in grooming behavior (Gispen et al., 1975), antipyretic (Murphy et al., 1983) and anti-inflammatory (Macaluso et al., 1994) responses, learning (Zhao et al., 1995), reproductive function (Schioth and Watanobe, 2002), and regulation of appetite and energy homeostasis (Chen et al., 2000; Fan et al., 1997; Huszar et al., 1997; Marsh et al., 1999; Schwartz and Wisse, 2000). There are several observations that suggest that the MC system is a prime candidate for regulating drug-seeking behavior. MCRs are expressed in brain regions thought to mediate drug self-administration, including the nucleus accumbens (NAcc), the hypothalamus, and the ventral tegmental area (VTA) (Alvaro et al., 1996; Griffon et al., 1994; Mountjoy et al., 1994; Roselli-Rehfuss et al., 1993). Interestingly, α-MSH administered into the VTA increases dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the NAcc (Lindblom et al., 2001), and chronic intracerebroventricular (ICV) infusion of the nonselective MCR agonist melanotan II (MTII) to rats increases dopamine D1 receptor binding in the NAcc and dopamine D2 receptor binding in the VTA, suggesting that MTII alters dopamine signaling in these regions (Lindblom et al., 2002a). Chronic treatment of a high dose of morphine decreases MC4 receptor (MC4R) mRNA expression in the NAcc, the periaqueductal gray, and neostriatum (Alvaro et al., 1996), brain regions that modulate drug reward, opiate tolerance, and psychomotor stimulation, respectively (Kalivas and Stewart, 1991; Koob and Bloom, 1988; Wise and Bozarth, 1987). On the other hand, chronic treatment with low doses of morphine or cocaine increases MC4R mRNA in the striatum and hippocampus (Alvaro et al., 2003). Consistent with a role in drug self-administration, central infusion of an MCR agonist decreases the acquisition of heroin self-administration in rats (van Ree et al., 1981). Ethanol has direct effects on central POMC and α-MSH activity (Angelogianni and Gianoulakis, 1993; Rainero et al., 1990). It is therefore possible that MC neuropeptides modulate neurobiological responses to ethanol and participate in the control of voluntary ethanol consumption. Several observations are consistent with this hypothesis. First, α-MSH is expressed in brain regions involved with neurobiological responses to ethanol, including the striatum, NAcc, VTA, amygdala, hippocampus, and hypothalamus (Bloch et al., 1979; Dube et al., 1978; Jacobowitz and O’Donohue, 1978; O’Donohue and Jacobowitz, 1980; O’Donohue et al., 1979; Yamazoe et al., 1984). Second, rats selectively bred for high ethanol drinking (AA [Alko, alcohol]) have low levels of MC3R in the shell of the NAcc but have high levels of MC3R and MC4R in various regions of the hypothalamus, when compared with low–ethanol-drinking rats (Lindblom et al., 2002b). Third, central infusion of MTII significantly reduces voluntary ethanol drinking in AA rats with an established history of ethanol intake (Ploj et al., 2002). Recently, MTII-induced reduction of ethanol consumption was shown to be receptor mediated and not associated with alterations of ethanol metabolism in C57BL/6 mice (Navarro et al., 2003). One objective of the present report was to study the role of selected MCRs in the modulation of MCR agonist–induced reduction of ethanol intake. In rodents, MC peptides act through five receptors (MC1R–MC5R) (Hadley and Haskell-Luevano, 1999). MC3R and MC4R are expressed at high levels in the brain (Alvaro et al., 1997), whereas MC1R and MC5R are detected at low levels and in only limited brain regions (Adan and Gispen, 1997; Barrett et al., 1994; Xia et al., 1995). MTII binds, with varying affinity, to all centrally expressed MCRs (Haskell-Luevano et al., 1997; Schioth et al., 1997). Thus, it is unclear which MCRs are important for modulating MTII-induced reductions of ethanol consumption (Navarro et al., 2003; Ploj et al., 2002). To assess the contribution of MC3R, we examined MTII-induced alteration of ethanol drinking in Mc3r–knock-out (Mc3r−/−) and wild-type (Mc3r+/+) mice. To assess the role of MC4R, we studied ethanol intake by C57BL/6J mice after central infusion of the highly selective MC4R agonist cyclo(NH-CH2-CH2-CO-His-d-Phe-Arg-Trp-Glu)-NH2. A second objective was to determine whether central administration of AgRP-(83-132) would increase ethanol consumption by mice. In vivo, AgRP-(83-132) is a potent and nonselective MCR antagonist (Quillan et al., 1998). Such results would strengthen the argument that MCR signaling plays an important role in the modulation of ethanol self-administration. Because MCR agonists reduce and MCR antagonists increase feeding (Hagan et al., 2000; Hohmann et al., 2000; Hollopeter et al., 1998; Marsh et al., 1999; Thiele et al., 1998), food intake was concurrently assessed in most studies described in the present report.

This report of the proceedings of a symposium presented at the 2004 Research Society on Alcoholism Meeting provides evidence linking stress during sobriety to craving that increases the risk for relapse. The initial presentation by Rajita Sinha summarized clinical evidence for the hypothesis that there is an increased sensitivity to stress-induced craving in alcoholics. During early abstinence, alcoholics who were confronted with stressful circumstances showed increased susceptibility for relapse. George Breese presented data demonstrating that stress could substitute for repeated withdrawals from chronic ethanol to induce anxiety-like behavior. This persistent adaptive change induced by multiple withdrawals allowed stress to induce an anxiety-like response that was absent in animals that were not previously exposed to chronic ethanol. Subsequently, Amanda Roberts reviewed evidence that increased drinking induced by stress was dependent on corticotropin-releasing factor (CRF). In addition, rats that were stressed during protracted abstinence exhibited anxiety-like behavior that was also dependent on CRF. Christopher Dayas indicated that stress increases the reinstatement of an alcohol-related cue. Moreover, this effect was enhanced by previous alcohol dependence. These interactive effects between stress and alcohol-related environmental stimuli depended on concurrent activation of endogenous opioid and CRF systems. A.D. Lê covered information that indicated that stress facilitated reinstatement to alcohol responding and summarized the influence of multiple deprivations on this interaction. David Overstreet provided evidence that restraint stress during repeated alcohol deprivations increases voluntary drinking in alcohol-preferring (P) rats that results in withdrawal-induced anxiety that is not observed in the absence of stress. Testing of drugs on the stress-induced voluntary drinking implicated serotonin and CRF involvement in the sensitized response. Collectively, the presentations provided convincing support for an involvement of stress in the cause of relapse and continuing alcohol abuse and suggested novel pharmacological approaches for treating relapse induced by stress.

Significant progress has been made in the development of several nonpeptide antagonists of the type 1 receptor for corticotropin-releasing factor (CRF). The present review outlines the properties of this drug class that point to their potential as agents for depression and/or anxiety. Behavioral tests of CRF1 receptor antagonists relevant to depression have been mixed. For example, most CRF1 receptor antagonists did not lower swim test immobility in a subacute paradigm, where three injections of the drug are given in the 24 hrs between a 15-min pre-swim and a 5-min test swim. However, reliable effects in other tests of antidepressant action were observed in the chronic mild stress protocol or the Flinders Sensitive Line rat that exhibits innately high swim test immobility when the drugs were given chronically. Because these latter tests have a very good record of predicting antidepressant activity, CRF1 receptor antagonists are good candidates for clinical trials for depression. Evidence indicates that the CRF1 receptor antagonists do not exhibit changes in anxiety-like behavior under basal conditions. However, this drug class effectively blocks the anxiogenic states produced by withdrawal from chronic alcohol, by exposure to stress, or in rats selectively bred for high anxiety. CRF1 receptor antagonists also prevent the anxiety associated with multiple ethanol withdrawals when given only during the earlier withdrawals. Thus, these agents may also have clinically relevant anxiolytic effects, not only in individuals with anxiety disorders but also in individuals who have anxiety episodes during alcohol or drug withdrawal. Drug Dev. Res. 65:191–204, 2005. © 2005 Wiley-Liss, Inc.

Background: Inhibition of NMDA receptor function in brain is believed to be an important action of ethanol (EtOH). To investigate EtOH inhibition of NMDA receptor responses in vivo, the interaction of these agents in brain after different routes of administration were investigated by using transcription factor Fos protein expression to follow NMDA receptor activation and EtOH inhibition of this response. Methods: The induction of Fos-like immunoreactivity (Fos-LI) in 38 regions of the rat brain was measured 2 hr after treatment with NMDA, EtOH, or both. To determine the relative contribution of abdominal drug effects on Fos induction, rats received either intraperitoneal (ip) or intragastric (ig) EtOH and ip or intravenous (iv) NMDA. Rats received EtOH (2.5 g/kg ip or 4 g/kg ig) or vehicle 15 min before NMDA (125 mg/kg ip or 60 mg/kg iv) or vehicle. Results: For the 38 forebrain regions examined, ip and iv NMDA significantly induced Fos-LI in 13 and 32 regions, respectively. These effects occurred without elicitation of tonic-clonic seizure activity and were strong after iv NMDA in the frontal, prefrontal, and cingulate cortices, supraoptic nucleus, anterior lateral septum, and dentate gyrus. For EtOH, prominent Fos-LI induction was found in the central amygdala, dorsolateral bed nucleus of the stria terminalis, Edinger-Westphal nucleus, and paraventricular hypothalamus. Despite ip and ig EtOH induction of Fos-LI in these regions, the major effect of EtOH was to block NMDA-induced Fos-LI in 8 of 13 (ip) and 27 of 32 (ig) of the NMDA-positive regions, respectively, including retrosplenial, cingulate, and medial prefrontal cortices, central amygdala, and taenia tecta. Conclusions: These results provide new evidence for the regionally specific functional interactions of EtOH on NMDA receptors in vivo. Moreover, these results support efforts to identify brain region–specific targets for EtOH and EtOH-induced changes in gene expression.

This paper summarizes a conference held at the National Institute of Child Health and Human Development on December 6-7, 1999, on self-injurious behavior [SIB] in developmental disabilities. Twenty-six of the top researchers in the U.S. from this field representing 13 different disciplines discussed environmental mechanisms, epidemiology, behavioral and pharmacological intervention strategies, neurochemical substrates, genetic syndromes in which SIB is a prominent behavioral phenotype, neurobiological and neurodevelopmental factors affecting SIB in humans as well as a variety of animal models of SIB. Findings over the last decade, especially new discoveries since 1995, were emphasized. SIB is a rapidly growing area of scientific interest to both basic and applied researchers. In many respects it is a model for the study of gene-brain-behavior relationships in developmental disabilities.

BACKGROUND Electrophysiological recording reveals that only a portion of cerebellar Purkinje neurons are sensitive to ethanol enhancement of gamma-aminobutyric acid (GABA) responses. Although activation of beta-adrenergic receptors permits ethanol enhancement of GABA function from some cerebellar Purkinje neurons, other neurons remain insensitive to ethanol. These findings are consistent with the finding that other external neural inputs are required to allow ethanol enhancement of GABA responses from Purkinje neurons. Because of a high expression of GABA(B) receptors on Purkinje cells, we tested whether activation of GABA(B) receptors might modulate the action of ethanol on GABA responsiveness. METHODS Extracellular single-unit electrophysiological recording was used to investigate the effects of ethanol on responses to GABA and muscimol (a GABA(A) agonist) from cerebellar Purkinje neurons. Drugs tested were baclophen (a GABA(B) agonist) and CGP35348 (a GABA(B) antagonist). RESULTS Ethanol did not enhance responses to GABA and muscimol from all Purkinje neurons. Systemic administration of the GABA(B) agonist, baclophen (3 mg/kg intravenously), permitted ethanol to enhance GABA inhibition from approximately 75% of cerebellar Purkinje neurons not initially enhanced by ethanol. Local iontophoretic application of baclophen to Purkinje neurons also allowed ethanol to enhance GABA and muscimol responsiveness from a portion of neurons in which ethanol initially did not affect their actions. An inhibitory action of ethanol on responses to GABA and muscimol, which was also influenced by baclophen, was observed from some Purkinje neurons. From Purkinje neurons initially sensitive to ethanol enhancement of GABA and muscimol function, administration of CGP35348, a GABA(B) antagonist, diminished the effect of ethanol on the responsiveness of these agonists from the majority (9/15) of neurons. CONCLUSIONS The present findings demonstrated that baclophen allows ethanol enhancement of GABA and muscimol responsiveness from some, but not all, cerebellar Purkinje neurons initially not sensitive to ethanol. Likewise, a GABA(B) antagonist can diminish ethanol enhancement of GABA and muscimol responses from some ethanol-sensitive neurons. Thus, these results emphasize that GABA(B) receptors on a portion of Purkinje neurons act as an auxiliary neural input that allows ethanol enhancement of GABA responses. Consequently, receptor structure alone does not account for the action of ethanol on GABA(A) receptor function on this cell type.

Previous research has suggested that rats tested at 28 to 30 days of age show a marked subsensitivity to the sedative effects of ethanol. In the present study, rats of different ages were tested for aerial righting following acute ethanol (3 g/kg) treatment These results were compared with the effects of the atypical benzodiazepine zolpidem (3 and 5 mg/kg) and pentobarbital (10 and 15 mg/kg). Animals tested at 25, 28, or 35 days of age were significantly less impaired by ethanol than preweanling rats (age 20 days) or older rats (age 65 to 75 days), whereas animals tested at 25 or 28 days of age were less impaired by the higher dose of zolpidem. With pentobarbital, the most distinct age-related trend was greater impairment in 20-day-old rats. Because ethanol may be active at the same type I GABA A receptor site selectively labeled by [ 3 H]zolpidem, levels of pH]zolpidem binding were determined for rats of different ages. Although some brain regions showed progressive increases in binding of [ 3 H]zolpidem across development, other regions demonstrated increased binding from day 12 or 17 to day 20, then a plateau of binding levels across days 20, 25, and 28, with further increases occurring by day 36 or day 60. This pattem was observed in the cingulate cortex, medial septal nucleus, globus pallidus, inferior colliculus, red nucleus, and cerebellum. Overall, the results indicate that the period of subsensitivity to the sedative effects of ethanol is coincident with a change in the developmental pattern of GABA A receptor sites targeted by [ 3 H]zolpidem.

To further understand the relationship between emotional state and alcohol intake in rats, the tendency to emit ultrasonic vocalizations in response to an aversive, but nonpainful, air puff stimulus was tested in several rat lines. Included in this group were Maudsley Reactive (MR) and Non-Reactive (MNR) rats, and several lines of rats with either high ethanol preference or a low ethanol preference: Preferring, (P), Alko-Alcohol (AA), and Fawn-Hooded (FH) animals; and Non-Preferring (NP), Alko-Non-Alcohol (ANA), and Flinders Resistant Line (FRL). MR rats emitted fewer ultrasonic vocalizations (USVs) and showed less preference for ethanol than did MNR animals. An overall analysis that included the P, NP, FH, FRL, AA, and ANA groups demonstrated a significant negative correlation between the total number of USVs emitted and ethanol consumption. NP, FRL, and especially ANA rats (low ethanol-preferring) emitted the most USVs--to an extent similar to that typically found for normal rats. The duration of vocalizing was higher only in the NP and the FRL rats the relative to their P and FH comparison groups, respectively. In the ethanol-preferring and nonpreferring lines, the numbers of USVs emitted correlated positively with the duration of vocalizing, but not with the latency to vocalize, which in turn did not correlate strongly with ethanol intake. The latency to vocalize did not correlate significantly with ethanol intake across all drinking lines or MR or MNR rats, but was found to be higher in FH and AA rats relative to their nondrinking comparison groups. These associations suggest that the relationship between emotional state and ethanol drinking is complex and cannot be attributed to a simple elevated state of anxiety or emotionality. Further examination of the central nervous system mechanisms mediating the difference in USVs between paired lines of ethanol-preferring and nonpreferring rats may identify neurochemical factors that predict ethanol preference.

A strong association has been observed between [ 3 H]zolpidem binding and the presence of γ-aminobutyric acid (GABA A ) receptor mRNA for α 1 -, β 2 -, and γ 2 -subunits in specific brain regions. This correlates with observed sensitivity of individual neurons to zolpidem and ethanol in these same regions. Previous studies using homogenate binding approaches showed small alterations in [ 3 H]zolpidem binding levels after chronic ethanol exposure. This study was undertaken to ascertain if there is regional specificity of the effects of chronic ethanol administration on [ 3 H]zolpidem binding levels. Chronic ethanol administration induced small, but significant alterations in [ 3 H]zolpidem (5 nM) binding in the inferior colliculus, substantia nigra, and the medial septum. [ 3 H]Zolpidem binding was increased in the inferior colliculus and substantia nigra, and decreased in the medial septum. No significant differences in [ 3 H]zolpidem binding were noted in any other brain area analyzed, including the cortex and cerebellum. These findings show that chronic ethanol administration has small effects on [ 3 H]zolpidem binding, although they occur in a site-specific and bidirectional manner. Moreover, there is no correlation between changes in [ 3 H]zolpidem binding and alterations in GABA A receptor subunit expression.

Self-injurious behavior (SIB) remains a serious problem among the mentally retarded because no known pharmacological agents block this behavior. This symptom is especially severe in Lesch-Nyhan syndrome (LNS), a genetic disorder associated with HPRT deficiency. Because the prominent neurobiological deficit in LNS is a loss of dopaminergic neurons, reduction of dopamine with 6-hydroxydopamine (6-OHDA) in rats during their development is proposed as a model of the dopamine deficiency in LNS and in mentally retarded individuals with SIB who may have this neurotransmitter deficiency. In behavioral testing of this model, dopamine agonists that activate D1-dopamine receptors induced SIB in adult rats with neonatal 6-OHDA-dopamine lesions, a change not seen in rats lesioned as adults. SIB also has been observed when muscimol is microinjected into the substantia nigra reticulata (SNR) of the neonatal-6-OHDA lesioned rats. D1-dopamine antagonists, as well as NMDA antagonists, have been found to block the SIB induced by L-DOPA in these neonatally lesioned rats. In addition to the reduced dopamine, LNS patients also have an increased striatal serotonin content, as do rats neonatally lesioned with 6-OHDA. Activation of serotonergic receptors with m-chlorophenylpiperazine has increased oral activity in neonatal-6-OHDA-lesioned rats; destruction of serotonin-containing neurons has blocked this effect caused by a D1-dopamine agonist. These data suggest that serotonin and corresponding serotonin receptors contribute to dysfunctions in the neonatal-6-OHDA-lesioned model. This work provides background support for the hypothesis that neonatal reduction of dopamine results in increased vulnerability to SIB as a result of adaptation within a neural circuit in the brain involving D1-dopamine receptors, the SNR, and glutamate-and serotonin-containing neurons. Functional mapping in neonatally lesioned rats using 14C-2-deoxyglucose (2-DG) uptake and Fos-like immunoreactivity (Fos-L1) has implicated the SNR, entopeduncular nucleus, globus pallidus, and subthalamic nucleus in the action of a D1-dopamine agonist. In addition, a generalized increase in Fos-L1, but not 2-DG uptake, is also induced in the striatum by a D1-dopamine agonist. The action of CGS-19755 and MK-801, NMDA antagonists, on the accumulation of Fos-L1 in the striatum induced by a D1-dopamine agonist also has been examined. Whereas CGS-19755 blocked the increase in striatal Fos-L1 induced by the D1-dopamine agonist, MK-801 did not. Because both drugs block SIB in the rat model, these findings suggest that the glutamatergic neuronal system that contributes to SIB is not associated with the striatum. The research being undertaken with the model of neonatal dopa-mine reduction may suggest new therapeutic approaches to the SIB observed in developmental disorders of unknown etiology, as well as the SIB associated with LNS. © 1995 Wiley-Liss, Inc.

[125I]RTI-55 is a newly synthesized cocaine congener that may offer advantages over other ligands previously used to examine cocaine binding sites. However, the in vitro pharmacological and anatomical characterization of [125I]RTI-55 binding sites has not been previously performed in human brain. To determine the specificity, stability, and feasibility of [125I]RTI-55 for use in radioligand binding assays in postmortem human tissue, a series of experiments were performed characterizing [125I]RTI-55 binding sites in human brain using homogenized membrane preparations and quantitative autoradiography. Analysis of the association, dissociation, and saturation data favored two-phase processes. A curve-fitting analysis of the data derived in saturation experiments found a high-affinity site with KD = 66 +/- 35 pM and Bmax = 13.2 +/- 10.1 pmol/g of tissue and a low-affinity site with KD = 1.52 +/- 0.55 nM and Bmax of 47.5 +/- 11.2 pmol/g of tissue. Competition by ligands known to bind to the dopamine transporter showed a rank order of RTI-55 > GBR-12909 > maxindol > WIN 35428 > = methylphenidate > (-)-cocaine > buproprion > (+)-amphetamine. Binding to serotonergic sites was evaluated in the midbrain. Results of the saturation experiment performed autoradiographically in the midbrain showed a single site with KD = 370 +/- 84 pM. It appears that [125I]RTI-55 should be useful in further studies of the regulation of cocaine binding sites using postmortem human specimens.

Because multiple withdrawals from chronic ethanol treatment facilitate the rate of kindling from the inferior collicular cortex, the following studies sought to identify potential sources of this long-term change in seizure sensitivity. When rats received 6 or 10 withdrawals from a 5-day ethanol liquid diet, a significant decrease was found in the threshold frequency for seizure genesis, 6-7 days post-withdrawal. The magnitude of this change was related to the number of withdrawals (6 withdrawals, -2.0 +/- 0.3 Hz; 10 withdrawals, -3.2 +/- 1.2 Hz). Thus, multiple ethanol withdrawals increased seizure sensitivity within the inferior collicular cortex. On the following day in the same animals, changes in inhibitory or excitatory function were evaluated within the inferior collicular cortex. We found a withdrawal-related increase in the effectiveness of bicuculline to reduce the seizure threshold current within the inferior collicular cortex. Seizure sensitivity to collicular N-methyl-D-aspartic acid (NMDA) microinjection was decreased after 6 ethanol withdrawals, and increased after 10 withdrawals, but control liquid diet animals exhibited similar responses to collicular NMDA microinjection. Therefore, multiple withdrawals from ethanol alters the seizure sensitivity within the inferior collicular cortex. One possible contribution to this change is a local decrease in GABA inhibitory function.

1. Acquisition of a two-way shuttle-box avoidance response is facilitated by ethanol. This facilitated acquisition of an avoidance response to ethanol was attenuated during withdrawal from chronic-ethanol diet intake (i.e. tolerance developed by ethanol). The deficit in the avoidance task after chronic ethanol treatment could be overcome by increasing the dose of ethanol. 2. Flumazenil, a benzodiazepine antagonist, also facilitated acquisition of the avoidance response in control rats. This response to flumazenil was significantly reduced during withdrawal from chronic-ethanol treatment. This reduced avoidance responding during withdrawal also could be overcome by increasing the dose of flumazenil. 3. The benzodiazepine-inverse agonist, RO 15-4513, produced a deficit in avoidance responding that was antagonized by both ethanol and flumazenil in a dose-related manner. 4. To determine whether flumazenil has the properties of a benzodiazepine agonist, it was established that, unlike the benzodiazepine chlordiazepoxide, flumazenil did not enhance the ethanol-induced deficit in the aerial righting reflex. Additionally, flumazenil blocked the action of chlordiazepoxide in this procedure, consistent with the benzodiazepine antagonist action of flumazenil. 5. Data collected are consistent with the hypothesis that an endogenous substance with the properties of a benzodiazepine-inverse agonist antagonizes the anticonflict actions of acutely administered ethanol during withdrawal from chronic-ethanol exposure.

Summary: The ontogeny of seizure genesis within the inferior collicular cortex was characterized in rats ranging in age from 3 days old to adult. Brief electrical stimulation of the right inferior collicular cortex in 30-day-old rats evoked poststimulus wild running behavior that coincided with afterdischarge activity in the inferior collicular cortex but not in the adjacent occipital cortex. Similar electrical stimulation in 16-day-old rats produced poststimulus wild running and jumping behaviors, which also coincided with afterdischarge in the inferior collicular cortex. In 10- and 5-day-old rats, electrical stimulation of the inferior collicular cortex produced poststimulus locomotion and coincident afterdischarge activity, but unlike older rats the locomotor behaviors consisted of forelimb paddling, hindlimb treading, and rolling/curling movements of the torso. Identical behaviors can be electrically elicited in 3-day-old rats. Although many of the seizure characteristics appear to be similar among the different age groups, 5-day-old rats were more sensitive to low frequency stimulation than 16-day-old rats, who in turn were more sensitive than adult rats. Thus, the inferior collicular cortex is capable of generating seizure activity in rats as young as 3 days of age, providing a focal model of neonatal seizure genesis. RESUME L'ontogenese de la genese des crises au niveau du cortex colliculaire inferieur a ete caracterisee chez des rats ages entre jours et I'age adulte. Une stimulation electrique breve du cortex colliculaire inferieur droit chez des rats ages de 30 jours a evoque un comportement de course sauvage post-stimulative, qui coincidait avec une activite de post-decharge au niveau du cortex colliculaire inferieur, mais non au niveau du cortex occipital adjacent. Une stimulation electrique semblable chez les rats ages de 16 jours a produit des comportements post-stimulatifs de course folle et de saut, qui coincidaient egalement avec la presence de post-decharges au niveau du cortex colliculaire inferieur. Chez des rats ages de 10 et 5 jours, la stimulation electrique du cortex colliculaire inferieur a produit une activite poststimulative de locomotion associee a une post-decharge, mais, contrairement aux rats plus ages, les comportements locomoteurs ont consiste en des mouvements de battements des members anterieurs, de trepignements des membres posterieurs et des mouvements d'enroulement au niveau du torse. Des comportements identiques peuvent ere provoques electriquement chez des rats ages de 3 jours. Bien que de nombreuses caracteristiques semblent similaires au niveau des differents groupes d'ages, les rats ages de 5 jours sont plus sensibles a la stimulation a basse frequence que les rats ages de 16 jours, ceux-ci etant plus sensibles que les rats adultes. Ainsi, le cortex colliculaire inferieur est capable de generer une activite critique chez des rats des I'age de 3 jours, ce qui fournit un modele focal d'epileptogenese neo-natale. RESUMEN en ratas de edades que oscilaban entre 3 dias y edad adulta se ha caracterizado la ontogenia de la genesis de los ataques en la corteza colicular inferior. La estimulacion electrica breve de la corteza colicular inferior derecha en ratas de 30 dias de edad evoco un comportamiento de carrera agitada que coincidia con la actividad post-descarga en la corteza colicular inferior pero no en la corteza occipital adyacente. Una estimulacion electrica semejante en ratas de 16 dias de edad produjo, tras el estimulo, un comportamiento de carrera agitada y saltos que tambien coincidio con las postdescargas en la corteza colicular inferior. En 10 ratas de 5 dias de edad la estimulacion electrica de la corteza colicular inferior produjo, tras el estimulo, locomotion coincidente con la actividad post-descarga pero, contrariamente a las otras ratas, 10s comportamientos locomotores consistieron en agitacion de extremidades anteriores, pedaleo con las extremidades posteriores y rodamientos con el torso. Comportamientos identicos fueron evocados electricamente en ratas de 3 dias de edad. A pesar de que las caracteristicas generales de los ataques parecen ser semejantes entre los diferentes grupos de edad, las ratas de 5 dias fueron mas sensibles a la estimulacion de baja frecuencia que las ratas de 16 dias las cuales, a su vez, fueron mas sensibles que las ratas adultas. Asi pues, la corteza colicular inferior es capaz de generar actividad epileptica en ratas tan jovenes como las de 3 dias lo que proporciona un modelo focal de la genesis de ataques neonatales. ZUSAMMENFASSUNG Es wird die Anfallsontogenese im inferioren killikularen Kortex bei Ratten im Alter von 3 Tagen bis zum Ausgewachsensein charakterisiert. Kurze elektrische Stimulationen des re. inferioren kollikularen Kortex bei 30 Tage alten Ratten fuhrte zu einem Verhalten mit wildem Umherrennen zusammen mit einer Nachentladungsaktivitat im inferioren kollikularen Kortex, jedoch nicht im anliegenden occipitalen Kortex. ahnliche elektrische Stimulation bei 16 Tagen alten Ratten fuhrte zu einem wilden Umherrennen und Springen, ebenfalls rnit Nachentladungen im inferioren kollikularen Kortex. Bei 10 und 5 Tage alten Ratten fuhrte die elektrische Stimulation des inferioren kollikularen Kortex zu einer post-stimulus Lokomotion zusammen mit Nachentladungen; aber anders als bei alteren Ratten bestand die Lokomotion in Ruderbeweggungen rnit der vorderen Extremitat, Treten mit der hinteren Extremitat und Rollbewegungen mit dem Stamm. Ein gleiches Verhalten kann durch Elektrostimulation bei 3 Tage alten Ratten ausgelost werden. Obwohl viele dieser Anfallscharakteristika in den unterschiedlichen Altersgruppen gleich aussehen, sind die 5 Tage alten Ratten sensitiver gegenuber niederfrequenter Stimulation als 16 Tage alten Ratten, die wiederum sensitiver als erwachsene Tiere sind. Der inferiore kollikulare Kortes ist in der Lage, Anfallsaktivitat bereits bei 3 Tage jungen Ratten zu produzieren und liefert somit ein Model1 einer fokalen neonatalen Anfallsentstehung.

The concept that centrally acting drugs influence behaviour by influencing neurotransmitter function at specific points controlling synaptic transmission is the basis of neuropharmacological research.The synapse is a specialized cellular interface that provides a physical and chemical link for facilitating communication between cells of the central nervous system (CNS). Keywords: agonist; antagonist; antidepressant; pain; neurotransmitter

The ethanol withdrawal syndrome includes anxiety as a prominent symptom. Because the extent that specific regions of brain are critical to the generation of this emotional state is unknown, Fos-like immunoreactivity (Fos-LI) was used to associate specific regions of the rat brain with the anxiety component of the ethanol withdrawal syndrome exacerbated by an air puff challenge in rats. Chronic ethanol liquid diet was administered intragastrically for 4 days or by having the rats consume the diet for 14 days. During withdrawal from either treatment protocol, Fos-LI was induced most prominently in forebrain areas, although the midbrain and hindbrain were also represented. Included in these Fos-U positive regions were many cortical regions, septum, accumbens, claustrum, amygdala, paraventricular nucleus of the thalamus and hypothalamus, hippocampus, locus coeruleus, and central gray. Fos-LI expression differed mostly in intensity between the two treatment and withdrawal protocols, with the gastric protocol producing the greatest Fos-LI induction in most brain regions. The threshold for air puff-induced ultrasonic vocalizations was decreased, and the number of vocalizations was increased and the period of vocalization was extended. These behavioral data indicate that aversively motivated responding in rats during ethanol withdrawal can be readily quantified with the ultrasonic vocalizations test without precipitating convulsive activity. Furthermore, a comparison of the effects of the air puff challenge versus withdrawal on Fos-LI indicated that the behavioral state induced in these two situations share functional neuroanatomical features. Some regions-such as the accumbens core, medial septum, subregions of the amygdala, hippocampus, substantia nigra, and cerebellum-exhibited little Fos-LI during withdrawal and also did not exhibit strong increases after the addition of the air puff challenge. However, other regions-such as the cerebral cortex (medial prefrontal, frontal, cingulate and ventrolateral orbital, claustrum, and tenia tecta), hypothalamus, and locus ceoruleus-exhibited Fos-LI at levels higher than that seen after either the ethanol withdrawal or puff challenge alone. These overlapping patterns of Fos-LI in specific regions of the brain, activated by both ethanol withdrawal and an anxiety provoking behavioral challenge, suggest that specific neuroanatomical sites in brain are associated with the symptom of anxiety observed during the ethanol withdrawal syndrome..

Hemophilus influenzae is the most common cause of bacterial meningitis in children, and a high percentage of survivors are at risk for long-term sequelae. To explore the mechanisms responsible for these sequelae, a neonatal rat model was used to define the behavioral, electrophysiological, and biochemical changes following meningitis. Three days after inoculation of 6-day-old rats with a minimum of 1 X 10(7) colony-forming units of a virulent Hemophilus influenzae, type b, cerebrospinal fluid and blood were cultured to confirm the presence of meningitis and bacteremia, respectively. At this time, forebrain norepinephrine and dopamine levels were significantly elevated in meningitic rats when standardized on a wet-weight basis. No changes in brain serotonin or heart norepinephrine levels could be found in the 9-day-old rats. No residual changes were found in steady-state concentrations of norepinephrine or dopamine in surviving adult rats. However, survivors that had had meningitis as neonates showed significant impairment in active and passive avoidance learning tasks and demonstrated a significantly higher level of activity during a habituation period in circular photocell activity cages. No change in the flinch-jump threshold was detected. Brainstem auditory evoked potentials showed delays of various waves in 3 of 10 Hemophilus influenzae type b-treated adult rats tested. These rats also exhibited markedly augmented locomotory responses to d-amphetamine (1 mg/kg), suggesting a long-lasting perturbation of central monoamine neuronal transmission.

The synthesis of threo-dl-methylphenidate (Ritalin®, 1), threo-dl-p-hydroxymethylphenidate (3), threo-dl-ritalinic acid (2), and threo-dl-p-hydroxyritalinic acid (4) with deuterium incorporated in the piperidine ring is described. These compounds were synthesized for use as internal standards for mass fragmentographic assays of methylphenidate and its metabolites. The synthetic scheme described resulted in less than 0.05% 2H0 in the piperidine ring in any of the preparations.

Summary: : Because under certain conditions, seizure activity electrically elicited from layers III and IV of the inferior collicular cortex can spread into forebrain regions, potential inferior collicular interactions with the amygdala were studied. Following acute electrical initiation of seizure activity from the inferior colliculus, no changes in amygdala EEG activity were noted. Following repetitive stimulation of the inferior colliculus, however, postictal spiking activity was noted in the amygdala, similar to interictal spiking reported for amygdala kindling, but this abnormal EEG activity did not coincide with any observable behavioral change. Conversely, the course of amygdala kindling in animals previously stimulated in the inferior colliculus progressed quite differently in comparison to control animals. Those animals repetitively stimulated in the inferior colliculus required a significantly greater number of amygdala kindling stimulations to reach class 5 seizure activity than did animals that received no inferior collicular stimulation and, unlike the controls, the chronic inferior collicular stimulation group usually regressed to class 2 or 3 seizure activity after the first class 5 seizure. Furthermore, the chronic inferior collicular stimulation group all exhibited wet-dog shakes during the amygdaloid kindling stimulation, whereas at no time did controls exhibit wet-dog shake behaviors. Finally, the seizure generalization from the inferior colliculus appears to be mediated by a mechanism distinct from the acute seizure activity, because a dose of diazepam (0.4 mg/kg), or carbamazepine (10 mg/kg), which had no effect on the wild running seizure, blocked behaviors indicative of seizure generalization. The significance of these results to epilepsy is discussed.

The cerebrospinal fluid (CSF) concentrations of three acid monoamine metabolites, two purines, and a group of amino acids were determined in two children with chroniccentral alveolar hypoventilation (Ondine's curse). The levels of all assayed neuroactive substances, metabolites, and amino acids, with one exception, were normal compared to an age-matched group of neurologically healthy children. The levels of the dopamine metabolite homovanillic acid in the children with Ondine's curse were approximately 2.4 times higher than expected for age range. The present findings may indicate a link between central nervous system dopamine activity and chronic central alveolar hypoventilation. Among other possible explanations, the changes seen might represent a primary alteration in dopamine activity or may reflect a change in dopamine turnover resulting from the chronic hypoventilation. Pediatr Pulmonol 1987; 3:131–135.

In normal rats lightly anesthetized with halothane apomorphine increased both resting and CO2--dependent minute ventilation (VM) by stimulating respiratory frequency (RF) whereas tidal volume (VT) was slighly decreased. Acute bilateral glossopharyngectomy, which impaired carotid body function, did not change the apomorphine effects in contrast to bilateral vagotomy, which abolished the RF response of the drug, but now increased VT. Intravenous infusion of dopamine increased VM, by elevating RF, and this effect was only slightly blunted by bilateral glossopharyngectomy but nearly abolished by vagotomy and totally eliminated by the combined procedures. The respiratory response to dopamine was depressed in rats with chronically destroyed central catecholaminergic neurons. These findings indicate that there may be two different dopaminergic stimulatory mechanisms that modulate RF—one peripheral and one central—and both depend upon afferent vagal activity. With impaired vagal function, however, two other dopaminergic stimulatory mechanisms effecting V., are evident—one central, and one peripheral which involves the carotid body.

—The urinary excretion of labelled metabolites was measured in dogs which had been injected intravenously or intraventricularly with [3H]norepinephrine or [14C]dopamine. [3H]Norepinephrine injected by either route produced more labelled 3-methoxy-4-hydroxy-phenylglycol than 3-methoxy-4-hydroxymandelic acid, as did [14C]dopamine after intravenous administration. In contrast, following the intraventricular injection of [14C]dopamine, more [14C]3-methoxy-4-hydroxymandelic acid was formed than [14C]3-methoxy-4-hydroxyphenylglycol. These observations suggest that the metabolism of exogenously-administered and endogenously-formed norepinephrine may proceed through different routes and that the predominant metabolite of norepinephrine in canine brain may be 3-methoxy-4-hydroxymandelic acid rather than 3-methoxy-4-hydroxyphenylglycol.

1. After intracisternal administration, 6-hydroxydopamine had a greater effect on brain noradrenaline than on dopamine.2. Administration of two doses of 6-hydroxydopamine increased the depletion of noradrenaline but not of dopamine.3. Small doses of 6-hydroxydopamine decreased the concentration of noradrenaline with little or no effect on dopamine. Tyrosine hydroxylase activity was not reduced with these treatments.4. While pargyline pretreatment offered no advantage in the depletion of brain noradrenaline after 6-hydroxydopamine, depletion of brain dopamine was greatly potentiated by this treatment. The reduction of striatal tyrosine hydroxylase activity observed after 6-hydroxydopamine was also potentiated by pargyline pretreatment.5. The amounts of labelled noradrenaline and dopamine formed from (3)H-tyrosine were greatly reduced by 6-hydroxydopamine treatment. After (3)H-DOPA, formation of noradrenaline was greatly reduced while formation of labelled dopamine was only moderately reduced suggesting that decarboxylation of DOPA can occur in other than catecholamine containing neurones.6. Desmethylimipramine and imipramine inhibited depletion of noradrenaline produced by 6-hydroxydopamine but did not alter depletion of dopamine. Reserpine did not inhibit depletion of catecholamines produced by 6-hydroxydopamine.7. Administration of 6-hydroxydopamine to developing rats lowered both noradrenaline and dopamine concentrations as well as the tyrosine hydroxylase activity in the brains of these animals.

In rats, after a single intracisternal injection of 6-hydroxydopamine (6-OHDA) electrical self stimulation was reduced by approximately 50%. The concentrations of noradrenaline and dopamine in the brain were reduced by 83%. A second injection of 6-OHDA reduced the concentration of these amines to 7% of control values and virtually eliminated self stimulation.