Time of day alters long-term sensitization to cocaine in rats.
To test the hypothesis that time of day influences the locomotor effects of cocaine in rats, we measured short- and long-term sensitization to cocaine at five different Zeitgeber times (ZT). Short-term sensitization was expressed equally at all ZTs tested. Long-term sensitization was expressed only at dark onset, suggesting a possible influence of melatonin. Exogenous melatonin given immediately before cocaine challenge slightly enhanced long-term sensitization. Taken together, the present results support a time-of-day influence on locomotor sensitization to cocaine.
Sleipness
Evan P
EP
Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, P.O. Box 646520, Pullman, 99164, USA. sleipnep@vetmed.wsu.edu
Sorg
Barbara A
BA
Jansen
Heiko T
HT
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002940:Circadian Rhythm / Q000502:physiology*; D003042:Cocaine / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000523:psychology; D007274:Injections, Intraperitoneal; D008297:Male; D008550:Melatonin / Q000494:pharmacology / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D003042:Cocaine; D008550:Melatonin