title: Alterations in ethanol seeking and self-administration following yohimbine in selectively bred alcohol-preferring (P) and high alcohol drinking (HAD-2) rats.
abstract: Evidence suggests that stress increases alcohol drinking and promotes relapse in humans. Animal models that assess related behaviors include the sipper tube ethanol self-administration and the stress-induced reinstatement paradigms. While selectively bred for the same high-ethanol-drinking behavior, alcohol-preferring P rats appear to show greater sensitivity to ethanol reinforcement than high-alcohol-drinking HAD rats. The present experiment tested the effects of the pharmacological stressor, yohimbine, on the motivation to seek and consume ethanol implementing a combined sipper tube/reinstatement model using male P and HAD-2 rats. Following training to self-administer ethanol using the sipper tube procedure, rats were tested for the effects of yohimbine (0.625-2.5 mg/kg) on ethanol drinking. Subsequently, rats were tested for the effects of 1.25 mg/kg yohimbine on reinstatement of ethanol seeking. Yohimbine (0.625 and 1.25 mg/kg) increased ethanol self-administration, and the latter dose also decreased latency to complete the response requirement. Yohimbine elicited reinstatement of ethanol seeking in both lines. HAD-2 rats drank more ethanol, but showed similar responding on the ethanol-associated lever compared to P rats. These findings extend both the reinstatement and sipper tube models and justify further exploration of this unique combined paradigm. Despite prior evidence suggesting that P rats are more motivated to seek and consume ethanol, differences in these behaviors between P and HAD-2 rats were not systematic in the present experiment. Further investigation may elucidate whether either selected line may be more sensitive than other selectively bred or outbred rats to stress-related changes in ethanol's reinforcing effects.
authors.affiliation: Department of Psychology, Indiana University-Purdue University, 402N Blackford St., LD124, Indianapolis, IN, United States. mbertholomey@mclean.harvard.edu
authors.forename: Megan L
authors.initials: ML
authors.lastname: Bertholomey
authors.forename: Terril L
authors.initials: TL
authors.lastname: Verplaetse
authors.forename: Cristine L
authors.initials: CL
authors.lastname: Czachowski
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology*; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D058999:Drug-Seeking Behavior / Q000187:drug effects*; D000431:Ethanol / Q000008:administration & dosage*; D005108:Extinction, Psychological / Q000187:drug effects; D008297:Male; D009042:Motivation / Q000187:drug effects*; D051381:Rats; D012646:Self Administration; D015016:Yohimbine / Q000494:pharmacology*
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D015016:Yohimbine; D000431:Ethanol