title: Central action of narcotic analgesics. VIII. The effect of dopaminergic stimulants on the action of analgesics in rats.
abstract: We investigated the influence of apomorphine, amphetamine, amantadine, dimethylaminoadamantane, nomifensine, ergometrine and beta-phenylethylamine on cataleptogenic and antinociceptive action of analgesics in rats. Nomifensine, apomorphine, beta-phenylethylamine, amantadine and ergometrine antagonized the catalepsy induced by morphine and codeine. Catalepsy induced by fentanyl was depressed only by nomifensine and apomorphine. Amphetamine only slightly antagonized the analgesic-induced catalepsy and the effects were not dose-dependent. Dimethylaminoadamantane did not antagonize catalepsy at all. Antinociceptive action of morphine and codeine was antagonized by apomorphine and amphetamine. Ergometrine counteracted the action of morphine, and beta-phenylethylamine decreased the action of pentazocine. The results suggest that: 1. There are differences in the mechanism of cataleptogenic action of the opiates (morphine and codeine) and fentanyl; 2. Catalepsy after analgesia differs from the catalepsy produced by neuroleptics in respect of interaction with such drugs as amphetamine, apomorphine or dimethylaminoadamantane. Analgesic-induced catalepsy seems to depend on the presynaptic inhibition of dopaminergic neurotransmission; 3. Stimulation of the central dopaminergic system in rat brain either does not change or weakly antagonizes the action of analgesics in the hot plate test.
mesh_terms: D000661:Amphetamine / Q000494:pharmacology; D000700:Analgesics / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D002375:Catalepsy / Q000139:chemically induced; D003061:Codeine / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D004347:Drug Interactions; D005283:Fentanyl / Q000494:pharmacology; D006801:Humans; D008297:Male; D009020:Morphine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D009020:Morphine; D000661:Amphetamine; D001058:Apomorphine; D005283:Fentanyl; D003061:Codeine; D004298:Dopamine