title: The influence of amphetamine and nomifensine on the development of morphine tolerance in the test of hypermotility in mice and catalepsy in rats.
abstract: The influence of drugs, which alter the brain catecholaminergic functions, on the development of morphine tolerance was studied. The experiments were carried out on mice in locomotor activity test, and on rats in catalepsy test. Tolerance to morphine was induced by subcutaneous implantation of morphine-base (37.5 mg) pellets. Amphetamine insignificantly diminished the development of tolerance to cataleptogenic effects of morphine in rats but markedly inhibited the development of tolerance to morphine-induced hyperactivity in mice. The latter action of amphetamine was blocked by pimozide. Administration of nomifensine induced the inhibition of the development of morphine tolerance in both tests. Pimozide also abolished this antagonistic action of nomifensine in locomotor activity test in mice. The obtained results have shown that intensification of dopaminergic neurotransmission induced the diminution of the development of tolerance to morphine.
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D002375:Catalepsy / Q000139:chemically induced*; D002395:Catecholamines / Q000502:physiology; D004343:Drug Implants; D004361:Drug Tolerance; D005260:Female; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D009627:Nomifensine / Q000494:pharmacology*; D010868:Pimozide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002395:Catecholamines; D004343:Drug Implants; D007546:Isoquinolines; D010868:Pimozide; D009627:Nomifensine; D009020:Morphine; D000661:Amphetamine