@article{216de30b25f14f1ba2b11ec68b3a4548,
title = "Differential effects of response-contingent and response-independent nicotine in rats",
abstract = "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. (C) 2000 Elsevier Science B.V.",
keywords = "Catecholamine, Corticosterone, Epinephrine, Nicotine, Norepinephrine, Self- administration, Yoking",
author = "Donny, {Eric C.} and Caggiula, {Anthony R.} and Christine Rose and Jacobs, {Kimberly S.} and Mielke, {Michelle M.} and Sved, {Alan F.}",
note = "Funding Information: Experimenter-administered nicotine has previously been shown to elevate plasma corticosterone levels in the rat (Cam and Bassett, 1983; Caggiula et al., 1991) . The present work demonstrates that RC/N also elevates corticosterone in a paradigm that supports robust nicotine self-administration (Corrigall and Coen, 1989; Donny et al., 1995, 1998) . However, in rats receiving RC/N, plasma levels of corticosterone return to baseline by the end of an hour despite an average of 9.43 additional nicotine infusions. The decrease in corticosterone levels from 15 min after the first infusion to the end of the 1-h session in the RC/N animals may reflect acute tolerance. This interpretation is supported by two additional observations. First, the average time between the most recent infusion received and the time of blood draw was 8.43 min at the second draw and 8.44 min at the end of the session (Table 1) , making differences due to the timing of infusions relative to blood draws an unlikely explanation for this decrease in RC/N animals. Second, corticosterone levels in RI/S animals changed little over the session and baseline corticosterone levels for all rats were in the expected range of resting levels for rats in the active (night) phase of their light–dark cycle (10–15 μg/dl), suggesting that the initial increase was a true drug effect and not the result of experimental procedures. ",
year = "2000",
month = aug,
day = "25",
doi = "10.1016/S0014-2999(00)00532-X",
language = "English (US)",
volume = "402",
pages = "231--240",
journal = "European Journal of Pharmacology",
issn = "0014-2999",
publisher = "Elsevier",
number = "3",
}