Differential effects of response-contingent and response-independent nicotine in rats.
Passive administration of nicotine activates the hypothalamic-pituitary-adrenocortical axis and sympathetic nervous system. However, little is known about the effects of self-administered nicotine. Drug-naive rats were trained to respond for food reinforcement and then tested in one, 1-h session in which they received response-contingent i.v. nicotine or response-independent i.v. nicotine or saline. Blood draws were taken immediately prior to the session, 15 min after the first infusion and immediately after the session. Both response-contingent and response-independent nicotine (RI/N) increased corticosterone within 15 min, however, corticosterone levels returned to baseline in animals receiving response-contingent nicotine (RC/N) by the end of the session while remaining elevated in those receiving RI/N. Furthermore, only RI/N increased plasma epinephrine and norepinephrine levels; RC/N produced no effect. These differences indicate that nicotine's acute effects are powerfully modified by the presence of a contingency relationship between drug administration and the animal's behavior and that this relationship develops very rapidly.
Donny
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Department of Psychology, University of Pittsburgh, 412 Langley Hall, Pittsburgh, PA 15260, USA. edonny@jhmi.edu
Caggiula
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Rose
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Jacobs
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D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D003345:Corticosterone / Q000097:blood; D004837:Epinephrine / Q000097:blood; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D009638:Norepinephrine / Q000097:blood; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D012646:Self Administration
D018722:Nicotinic Agonists; D009538:Nicotine; D003345:Corticosterone; D009638:Norepinephrine; D004837:Epinephrine