Authors: Stephen T Hansen Gregory P Mark
Publish Date: 2007/05/27
Volume: 194, Issue: 1, Pages: 53-61
Abstract
Escalation from moderate to excessive drug intake is a hallmark of human addiction that can be modeled in rats by giving them longer daily access time to selfadminister cocaine Nicotine and cocaine are commonly coabused drugs in humans and recent work in animals suggests that activation of nicotinic acetylcholine receptors nAChR can increase cocaine selfadministrationControl rats selfadministered cocaine 075 mg/kg/infusion for either 1 or 6 h per day Experimental groups had the nAChR antagonist mecamylamine MEC added to the cocaine solution for 5 days after the transition from short 1 h per day to long access 6 h per day for cocaine selfadministration After 5 days MEC was removed from the cocaine solutionControl rats and rats that received a low dose of MEC 7 μg/infusion with cocaine increased their average hourly intake over 5 days of 6 h per day cocaine access Rats that received a higher dose of MEC 70 μg/infusion did not increase their intake of cocaine during 6 h access but continued to selfadminister cocaine When MEC was removed this group showed an escalation in cocaine selfadministration MEC did not alter cocaine intake in a group that had continuous 1 h accessAntagonism of nAChRs during the initial exposure to extended cocaine selfadministration access time prevented escalation of but did not eliminate drug intake These findings indicate that MECsensitive nAChRs are critical for determining cocaine intake as a function of longer access time
Keywords: