Cocaine-induced effects on isolation stress in neonatal rats.
The effects of cocaine administration on isolation-induced vocalizations and activity levels in 10-day-old rat pups were examined. Day 10 pups given cocaine (1.25, 2.5, 5, 10, & 20 mg/kg ip) vocalized significantly less than their caffeine- (10 mg/kg) and saline-administered siblings during a 5-min isolation period. Cocaine- and caffeine-administered pups also demonstrated a significant increase in overall activity compared with controls. In addition, intraperitoneal administration of the dopamine antagonist haloperidol (0.5 & 1.0 mg/kg) before 1.25 and 2.5 mg/kg cocaine produced a significant elevation in vocalizations compared with saline pretreatment, which indicates a blocking of cocaine's effect on calling behavior. These results suggest that the endogenous dopamine system involved with reinforcement and reward may quell the stress of isolation in the infant rat.
Kehoe
P
P
Department of Psychology, Trinity College, Hartford, Connecticut 06106.
Boylan
C B
CB
D000818:Animals; D000831:Animals, Newborn; D001143:Arousal / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects; D012931:Social Environment; D012934:Social Isolation; D014828:Vocalization, Animal / Q000187:drug effects*
D011954:Receptors, Dopamine; D003042:Cocaine