Bremazocine induces antinociception, but prevents opioid-induced constipation and catatonia in rats and precipitates withdrawal in morphine-dependent rats

Paola Petrillo, Maria Concetta Gambino, Alessandra Tavani

Research output: Contribution to journalArticlepeer-review

Abstract

Some in vivo agonist and antagonist properties of the putative k-compound bremazocine were characterized in rats. Bremazocine, at doses from 0.015-32 mg/kg i.p., delayed nociceptive reaction on a 55°C hot-plate with a dose-response curve not readily fitting a single straight line; this effect was antagonized by high doses of naloxone. In the same rats bremazocine did not delay the intestinal transit of a charcoal meal fed 5 min earlier and prevented morphine-induced constipation. This antagonism appeared to be opioif-specific and competitive, with apparent pA2 value 8.56. Catatonia induced by etorphine (0.004 mg/kg s.c.) and constipation induced by etorphine (0.004 mg/kg s.c.) and D-Ala2-D-Leu5-enkephalin (0.1 mg/kg i.p.) were completely antagonized by bremazocine (0.03-8 mg/kg i.p.). Antinociception induced by morphine (10 mg/kg i.v.) and etorphine (0.004 mg/kg s.c.) was only partly prevented. Naloxone (1 mg/kg) and bremazocine (0.015-1 mg/kg i.p.) precipitated a withdrawal syndrome, evaluated as jumping frequency, in rats rendered dependent to morphine. These data suggest the involvement of more than one opioid receptor population in bremazocine action in vivo.

Original languageEnglish
Pages (from-to)917-927
Number of pages11
JournalLife Sciences
Volume35
Issue number9
DOIs
Publication statusPublished - Aug 27 1984

ASJC Scopus subject areas

  • Pharmacology

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