Conditioned aversion after delay place conditioning with nicotine.
Rats received subcutaneous injections of either nicotine (NIC; 0.05-0.8 mg/kg) or vehicle [VEH (phosphate buffer); 1 ml/kg] immediately after conditioning sessions in a place-conditioning paradigm (delay conditioning). NIC was paired for three delay-conditioning sessions with one environment of a three-compartment place-conditioning apparatus; VEH was paired with another environment. The subjects were then tested for place preference or aversion by determining the proportion of time spent in each compartment during a 15-min test session. Delay conditioning with NIC only produced a dose-related place aversion (greater time was spent in the VEH-paired chamber on test day). Place aversion was evident when NIC, 0.8 mg/kg, was administered either immediately or 5 min after conditioning sessions but not when given 15 min after conditioning. Chlorisondamine (5 micrograms, lateral ventricle), but not saline, administered 2 weeks prior to delay conditioning with 0.8 mg/kg NIC completely blocked the NIC-induced place aversion. These data suggest that delay conditioning with NIC produces place aversion by a central mechanism. Since standard conditioning (NIC injection immediately before the place-conditioning sessions) with NIC only produced dose-related place preferences (Fudala et al. 1985; Fudala and Iwamoto 1986), the time of administration of the unconditioned stimulus is a strong determinant of the place-conditioning effects of NIC.
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D002714:Chlorisondamine / Q000494:pharmacology; D003214:Conditioning, Classical / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012931:Social Environment
D009538:Nicotine; D002714:Chlorisondamine