Autoshaping i.v. cocaine self-administration in rats: effects of nondrug alternative reinforcers on acquisition

Abstract

The purpose of this experiment was to examine the effects of a nondrug alternative reinforcer and feeding conditions on the acquisition of cocaine self-administration. Rats were autoshaped to press a lever that resulted in a 0.2 mg/kg i.v. cocaine infusion. Responses on the lever were monitored during six consecutive autoshaping sessions that occurred each day. A retractable lever was inserted into the operant chamber on a random time 60 s schedule 10 times per session for six sessions that began each hour. Each day the six autoshaping sessions were followed by a 6-h cocaine self-administration session. During self-administration the lever remained extended, and each response on the lever resulted in a cocaine infusion (0.2 mg/kg). The criterion for acquisition of cocaine-reinforced behavior was met when there were 5 consecutive days during which the mean number of infusions during the 6-h self-administration session was at least 100. This procedure was repeated daily until the criterion was met or 30 days elapsed. The rats were also trained to respond on lick-operated automatic drinking devices that delivered 0.05 ml water or a glucose and saccharin solution (G + S) contingent upon each lick response. Five groups of 12-14 rats were compared. The first four groups constituted a 2 x 2 factorial design whereby either G + S or water was available in the home cage for 3 weeks before autoshaping began and G + S or water was available in the operant chamber during autoshaping. These groups were limited to 20 g food per day and all had free access to water.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Studies of Addictive Behavior

“…This preference shift occurred regardless of the dose of cocaine available and even following a long history of extended access to cocaine self-administration Cantin et al 2010). These findings are generally consistent with previous research (Carroll et al 1989;Carroll and Lac 1993) and with recent behavioral economics studies showing that food (or sucrose) demand was more inelastic than cocaine demand (Christensen et al 2008; Koffarnus and Woods 2011; for review, see Kearns et al 2011). They are also congruent with a recent study showing that mice preferred drinking sucrose over direct optostimulation of midbrain dopamine neurons (Domingos et al 2011).…”

Behavioral characteristics and neurobiological substrates shared by Pavlovian sign-tracking and drug abuse

“…For example, Carroll and her associates have reported that pairings of the insertion of a lever CS with intravenous administration of drug reward US induced the automatic "shaping" of lever-pressing for drug self-administration in rats. Procedures of this sort have been employed to induce reliable leverpressing for the self-administration of the cocaine US (Carroll and Lac, 1993, 1998Specker et al, 1994;Gahtan et al, 1996;Lynch and Carroll, 1999;Lynch et al, 2001;Campbell and Carroll, 2001;Campbell et al, 2002;Carroll et al, 2002;Roth et al, 2002; see also Panlilio et al, 1996;Weiss et al, 2003 c.f., Di Ciano andKearns and Weiss, 2004), orthe self-administration of the amphetamine US (Carroll and Lac, 1997) or the self-administration of the heroin US (Lynch and Carroll, 1999;Carroll et al, 2002;Roth et al, 2002). In all of these studies, rats developed increasingly frequent lever-pressing as a function of experience with repeated pairings of lever CS with rewarding drug US.…”

Acquisition of Nicotine Self-Administration in Adolescent Rats Given Prolonged Access to the Drug

“…Food restriction also elevates plasma corticosterone (Marinelli et al, 1996), which enhances the activity of the underlying dopaminergic reward system (Barrot et al, 2000;Marinelli and Piazza, 2002). Therefore, animals trained using food restriction demonstrated enhanced motivation (Carroll and Lac, 1993;Piazza and Le Moal, 1996) when nicotine first became available. This confounding factor precludes the possibility of attributing the acquisition of SA behavior to nicotine per se.…”