Behavioural pharmacology
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Behavioural pharmacology · Mar 1996
Tolerance to the discriminative stimulus and reinforcing effects of ketamine.
In order to examine whether tolerance develops to the discriminative stimulus and reinforcing effects of ketamine, rats were trained either to discriminate ketamine (10mg/kg) from saline or to self-administer ketamine (1.1mg/kg/injection), and then treated with chronic ketamine (32mg/kg), administered i.p. every 8 hours for 7 days. No shift in the dose-response curve for either paradigm was obtained following this chronic regimen. ⋯ These results suggest that tolerance to the discriminative stimulus and reinforcing effects of ketamine develops during training. Examination of the self-administration training data support this assumption, since inter-reinforcer time decreases, reflecting an increase in ketamine intake over training sessions.
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Behavioural pharmacology · Feb 1993
Generalization of behavioral history across responses in the reversal of the effects of cocaine and d-amphetamine on the punished behavior of squirrel monkeys.
Previous research has demonstrated that the effects of d-amphetamine on punished lever pressing of squirrel monkeys are modified by an avoidance history in which lever pressing postpones shock. In the present experiment generalization of behavioral history across responses was assessed by determining the effects of d-amphetamine and cocaine on punished lever pressing of squirrel monkeys before and after exposure to an avoidance procedure in which a chain-pulling response postponed shock. The punishment schedule consisted of a fixed-interval 5-min schedule of food delivery in which every 30 lever presses produced a 5-mA electric shock. ⋯ This experiment demonstrates that avoidance-dependent upward shifts in the dose-response curves of d-amphetamine and cocaine can occur when the punishment and avoidance responses differ, and that original effects can be partially restored when both responses are available simultaneously. The results suggest that generalization across responses of the effects of a critical behavioral history may be a general property of behavioral history phenomena within behavioral pharmacology. These findings underscore the generality and importance of behavioral history as a modulatory influence on the effects of abused drugs.