Background: Studies in rodents have determined that intermittent exposure to alcohol vapor can increase subsequent ethanol self-administration, measured with operant and 2-bottle choice procedures. Two key procedural factors in demonstrating increased alcohol intake are the establishment of stable alcohol self-administration before alcohol vapor exposure and the number of bouts of intermittent vapor exposure. The present studies provide additional behavioral validation and initial pharmacological validation of this withdrawal-associated drinking procedure.Methods: Studies at 2 different sites (Portland and Scripps) examined the effect of intermittent ethanol vapor exposure (3 cycles of 16 hours of ethanol vapor18 hours air) on 2-hour limited access ethanol preference drinking in male C57BL/6 mice. Separate studies tested 10 or 15% (v/v) ethanol concentrations, and measured intake during the circadian dark. In one study, before measuring ethanol intake after the second bout of intermittent vapor exposure, mice were tested for handlinginduced convulsions (HICs) indicative of physical dependence on ethanol. In a second study, the effect of bilateral infusions of the corticotropin-releasing factor (CRF) receptor antagonist D-Phe-CRF(12-41) (0.25 mg/0.5 mL) into the central nucleus of the amygdala (CeA) on ethanol intake was compared in vapor-exposed animals and air controls.Results: Intermittent ethanol vapor exposure significantly increased ethanol intake by 30 to 40%, and the mice had higher blood ethanol concentrations than controls. Intra-amygdala infusions of D-Phe-CRF(12-41) significantly decreased the withdrawal-associated increase in ethanol intake without altering ethanol consumption in controls. Following the second bout of intermittent vapor exposure, mice exhibited an increase in HICs, when compared with their own baseline scores or the air controls.Conclusions: Intermittent alcohol vapor exposure significantly increased alcohol intake and produced signs of physical dependence. Initial pharmacological studies suggest that manipulation of the CRF system in the CeA can block this increased alcohol intake.

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Binge drinking, defined as achieving blood ethanol concentrations (BEC) of 80 mg%, has been increasing in adolescents and was reported to predispose later physical dependence. The present experiments utilized an animal model of binge drinking to compare the effect of ethanol “binge” experience during adolescence or adulthood on subsequent ethanol intake in male and female C57BL/6 mice. Adolescent and adult mice were initially exposed to the scheduled high alcohol consumption procedure, which produces BECs that exceed the levels for binge drinking following a 30 min ethanol session every third day. Ethanol intake and BECs were significantly higher in the adolescent (∼3 g/kg, 199 mg%) versus adult (∼2 g/kg, 135 mg%) mice during the first three ethanol sessions, but were more equivalent during the final two ethanol sessions (1.85-2.0 g/kg, 129-143 mg%). Then, separate groups of the ethanol experienced mice were tested with ethanol naïve adolescent and adult mice for 2-hr limited access (10 and 20% solutions) or 24-hr (5, 10 and 20% solutions) ethanol preference drinking. Limited access ethanol intake was significantly higher in female versus male mice, but was not altered by age or ethanol experience. In contrast, 24-hr ethanol intake was significantly higher in the adolescent versus adult mice and in female versus male mice. Furthermore, binge drinking experience in the adolescent mice significantly increased subsequent ethanol intake, primarily due to intake in female mice. Thus, adolescent binge drinking significantly increased unlimited ethanol intake during adulthood, with female mice more susceptible to this effect.

Previous studies using genetic and lesion approaches have shown that the neuropeptide Urocortin 1 (Ucn1) is involved in regulating alcohol consumption. Ucn1 is a corticotropin releasing factor (CRF)-like peptide that binds CRF1 and CRF2 receptors. Perioculomotor urocortin-containing neurons (pIIIu), also known as the non-preganglionic Edinger-Westphal nucleus, are the major source of Ucn1 in the brain and are known to innervate the lateral septum. Thus, the present study tested whether Ucn1 could regulate alcohol consumption through the lateral septum. In a series of experiments Ucn1 or CRF were bilaterally injected at various doses into the lateral septum of male C57BL/6J mice. Consumption of 20% v/v ethanol or water was tested immediately after the injections using a modification of a 2-hour limited access sweetener-free "drinking-in-the-dark" procedure. Ucn1 significantly suppressed ethanol consumption when administered prior to the third ethanol drinking session (the expression phase of ethanol drinking) at doses as low as 6 pmol. Ethanol intake was differentially sensitive to Ucn1, as equivalent doses of this peptide did not suppress water consumption. In contrast, CRF suppressed both ethanol and water intake at 40 and 60 pmol, but not at lower doses. Repeated administration of Ucn1 during the acquisition of alcohol consumption showed that 40 pmol (but not 2 or 0.1 pmol) significantly attenuated ethanol intake. Repeated administration of Ucn1 also resulted in a decrease of ethanol intake in sham-injected animals, a finding suggesting that the suppressive effect of Ucn1 on ethanol intake can be conditioned. Taken together, these studies confirm the importance of lateral septum innervation by Ucn1 in the regulation of alcohol consumption.A variety of evidence has suggested that the neuropeptide corticotropin releasing factor (CRF) plays an important role in the development of alcoholism (Koob and Le Moal, 2001). CRF is known as the prototypical ligand acting on CRF receptors (Vale et al., 1981). However, recent studies indicate that CRF is not the sole ligand of CRF receptors, and that the endogenous neuropeptides urocortin 1 (Ucn1), urocortin 2 (Ucn2, also known as stresscopin-related peptide) and urocortin 3 (Ucn3, also known as stresscopin) also bind these receptors (Vaughan et al., 1995, Hsu and Hsueh, 2001. Moreover, these studies show that all three urocortins have higher affinity than CRF at CRF2 receptors, and that Ucn1 has higher or equal affinity than CRF at CRF1 receptors. The complexity of the CRF system requires that the potential role of each of the CRF-like peptides be considered in studying the pathogenesis of alcoholism. corresponding authorPublisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that d...

Background-Allopregnanolone (ALLO) is a physiologically-relevant neurosteroid modulator of GABA A receptors, and it exhibits a psychopharmacological profile that closely resembles the postingestive effects of ethanol. The 5α-reductase inhibitor finasteride (FIN), which inhibits biosynthesis of ALLO and structurally-related neurosteroids, was previously demonstrated to reduce the maintenance of limited-access ethanol consumption. The primary aim of the current work was to determine whether FIN would reduce the acquisition of drinking in ethanol-naïve mice.