Caffeine, nicotine and mecamylamine share stimulus properties in the preexposure conditioned taste aversion procedure.
BACKGROUND
The present study examined whether nicotine and caffeine, two of the most widely used psychoactive drugs, share stimulus properties in the preexposure conditioned taste aversion (CTA) procedure.


OBJECTIVE
To determine whether nicotine would attenuate the formation of a caffeine-induced CTA and further assess whether pretreatment with mecamylamine, a nicotinic receptor antagonist, would reverse nicotine's attenuating effect of a caffeine-induced CTA.


METHODS
Male Wistar rats were preexposed with one of three doses of nicotine (0.6, 1.2 and 2.0 mg/kg, s.c.) for three consecutive days, then 24 h following the final preexposure injection were conditioned with caffeine (20 mg/kg and 30 mg/kg, i.p.) in a standard two-bottle test. There were four conditioning trials and four drug-free test days. In a follow-up study, rats were pretreated with mecamylamine (2 mg/kg, i.p.) prior to preexposure injections with nicotine (0.6 mg/kg, i.p.), then subsequently conditioned with caffeine (20 mg/kg, i.p.) as described above.


RESULTS
The lowest nicotine dose (0.6 mg/kg) attenuated the caffeine induced CTAs (20 mg/kg and 30 mg/kg) but the higher nicotine doses showed no such attenuating effect. In addition, mecamylamine reversed the nicotine-induced attenuation of the caffeine-induced CTA and also directly attenuated it.


CONCLUSIONS
These results suggested that caffeine, nicotine and mecamylamine share overlapping stimulus properties and that the nature of this relationship may involve action at the nicotinic-cholinergic receptor.
Kunin
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D
Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, 1455 de Maisonneuve Boulevard W., H-1013, Montreal, Quebec, Canada H3G1M8. kunin@csbn.concordia.ca
Bloch
R T
RT
Smith
B R
BR
Amit
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Z
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology*; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013649:Taste / Q000187:drug effects* / Q000502:physiology
D000697:Central Nervous System Stimulants; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D002110:Caffeine; D008464:Mecamylamine; D009538:Nicotine