Central action of narcotic analgesics. VIII. the effect of dopaminergic stimulants on the action of analgesics in rats
Malec, D.; Langwiński, R.
Polish Journal of Pharmacology and Pharmacy 33(3): 273-282
1981
ISSN/ISBN: 0301-0244 PMID: 6119681 Document Number: 171861
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.