Aging changes the effects of cocaine on vigilance task performance of rats.
To investigate age-related behavioral changes with the administration of cocaine, young (6-10 mo), middle-aged (12-18 mo), young-old (21-24 mo), and old (25-36 mo) rats that had been trained on a 2-choice, discrete trial vigilance task were tested under different doses of cocaine. The young and middle-aged rats exhibited significantly increased accuracy and decreased choice latencies following 2.5 mg/kg cocaine. A 15.0 mg/kg dose increased variability in these measures and increased food retrieval latencies. The young-old and old rats exhibited no significant changes in accuracy or choice latency to 1.25, 2.5, and 5.0 mg/kg cocaine; however, a dose of 15.0 mg/kg significantly reduced accuracy in both these groups and increased choice latencies in the old animals. Also, doses of 5.0 and 15.0 mg/kg tended to increase food retrieval latencies more in the two older groups than in the two younger groups. These results indicate that, rather than a simple increase or decrease in sensitivity, there is a qualitative change in cocaine's behavioral effects as rats age. These findings may reconcile long-standing discrepancies in the literature regarding age-related changes in the behavioral effects of amphetamine, with actions and effects very similar to those of cocaine.
Grilly
D M
DM
Department of Psychology, Cleveland State University, OH 44115.
D000375:Aging / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000187:drug effects* / Q000502:physiology*; D001288:Attention / Q000187:drug effects* / Q000502:physiology*; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005502:Food; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology
D003042:Cocaine