The effects of morphine and delta-9-tetrahydrocannabinol on motor activity in rats.
Acute treatment of rats either by high doses of morphine or delta 9-tetrahydrocannabinol (THC) decreased locomotor activity. Naloxone reversed morphine-induced depression completely and reversed THC-induced depression only partially. On day 3 of treatment, tolerance developed to the locomotor inhibitory action of THC or morphine and partial cross-tolerance was observed to the depressant action of THC. Naloxone slightly depressed locomotor activity in THC-tolerant rats, but increased motor activity in morphine-tolerant rats.
D000818:Animals; D013759:Dronabinol / Q000494:pharmacology*; D004361:Drug Tolerance; D006801:Humans; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009021:Morphine Dependence / Q000523:psychology; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats
D009020:Morphine; D013759:Dronabinol