Temporal factors in the effect of restraint stress on morphine-induced behavioral sensitization in the rat.
The role of associative factors in the effect of 15 min/day of restraint stress on morphine-induced behavioral sensitization was examined. Male rats were initially given seven systemic (10 mg/kg, IP) or intraventral tegmental area (VTA, 5 micrograms/side) [corrected] injections of morphine, and were exposed to restraint, either just prior to drug injection (Paired-Stress) or 24 h after injection (Unpaired-Stress), or to no restraint (Control). In subsequent tests for behavioral sensitization to low doses of morphine (0.75 or 3.0 mg/kg, IP), animals in the Paired-Stress condition were more active than animals in the Unpaired-Stress or Control conditions. These results indicate that temporal and possibly associative factors may contribute to stress-induced changes in sensitization to the behavioral activating effects of opioids.
Shaham
Y
Y
Department of Psychology, Concordia University, Montreal, Quebec, Canada.
Kelsey
J E
JE
Stewart
J
J
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004298:Dopamine / Q000502:physiology; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000523:psychology*; D013997:Time Factors; D017557:Ventral Tegmental Area / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D009020:Morphine; D004298:Dopamine