title: Cocaine-induced hypophagia and hyperlocomotion in rats are attenuated by prazosin.
abstract: The present studies examined the effects of antagonizing alpha(1)-adrenoceptors via systemic administration of prazosin on the behavioral actions of cocaine in rats, including induction of locomotion and suppression of eating. In Experiment 1, locomotor activity was monitored in automated chambers for 80 min in adult male rats pretreated with the alpha(1)-adrenoceptor antagonist prazosin (0, 0.5, or 2 mg/kg, i.p.) and then treated (i.p.) with either 0, 10, 20, or 40 mg/kg cocaine hydrochloride. Cocaine dose-dependently increased total distance traveled and the number of stereotypy counts, and significantly decreased rest time. Each dose of prazosin produced a significant attenuation of the locomotor effects of a limited range of cocaine doses (i.e. 10 and/or 20 mg/kg cocaine, but not 40 mg/kg cocaine). Prazosin alone did not alter any measure of locomotion. In Experiment 2, eating and drinking were monitored for 60 min in male rats pretreated with prazosin (0, 1, and 2 mg/kg, i.p.) and then treated with 0, 10, 20, or 40 mg/kg (i.p.) cocaine. Rats pretreated with vehicle exhibited a dose-dependent suppression of eating, but not drinking, to cocaine. The impact of prazosin on cocaine-induced hypophagia paralleled that noted for locomotion in that administration of prazosin significantly attenuated the hypophagic action of 20 mg/kg cocaine, but not that of 40 mg/kg cocaine. These findings confirm earlier studies noting a partial role for alpha(1)-adrenoceptors in the locomotor stimulant actions of cocaine and extend those findings to the feeding-inhibitory actions of cocaine.
authors.affiliation: Department of Psychology, Texas A&M University, College Station, TX 77843-4235, USA. PJW@PSYC.TAMU.EDU
authors.forename: Paul
authors.initials: P
authors.lastname: Wellman
authors.forename: Dao
authors.initials: D
authors.lastname: Ho
authors.forename: Antonio
authors.initials: A
authors.lastname: Cepeda-Benito
authors.forename: Larry
authors.initials: L
authors.lastname: Bellinger
authors.forename: Jack
authors.initials: J
authors.lastname: Nation
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D011224:Prazosin / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000317:Adrenergic alpha-Antagonists; D003042:Cocaine; D011224:Prazosin