Actions of nicotine on the acquisition of an autoshaped lever-touch response in rats.
Experimentally naive male, Sprague-Dawley rats maintained at 85% of their original body weight were trained to touch a retractable lever that was presented on a random interval 48-s schedule. The lever retracted when touched or after 15 s had elapsed, and one 45 mg food pellet was delivered simultaneously with lever retraction or after an 8-s delay. Rats received ten daily sessions each consisting of ten lever presentations. Nicotine (0.25-0.8 mg/kg SC) administration, either 15 min prior to (pre-session) or immediately after (post-session) the daily autoshaping sessions, caused a significant dose-related impairment of acquisition with the post-session injections having the greater effect. Low doses of nicotine (0.025-0.1 mg/kg SC) had little effect on acquisition when injected pre-session or post-session. Injections of 0.45 mg/kg nicotine either immediately (t = 0) or at +5 min after the daily sessions impaired acquisition of the lever-touch response. Nicotine injected at +15, +30, +60, or +120 min had no effect on acquisition. A single intraventricular injection of the ganglionic blocker chlorisondamine (5 micrograms) 2 weeks prior to autoshaping blocked the impairment produced by 0.45 mg/kg nicotine. Post-session injections of nicotine did not alter the lever-touch behavior of well-trained animals, but suppressed responding in animals that were partially trained. Thus, nicotine-induced impairment of the autoshaped lever-touch response is dose dependent, centrally mediated, occurs within 5 min of a SC injection, and may interfere with post-training consolidation processes.
D000818:Animals; D002714:Chlorisondamine / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D007276:Injections, Intraventricular; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011978:Receptors, Nicotinic / Q000187:drug effects
D011978:Receptors, Nicotinic; D009538:Nicotine; D002714:Chlorisondamine