EFFECT OF THE INTRAPERITONEAL ADMINISTRATION OF SALMON-CALCITONIN ON THE IN-VITRO ACTIONS OF OPIOID AGONISTS

1. The interaction of intraperitoneal administration of salmon-calcito nin with opioids was studied. The study was carried out using guinea p ig ileum (mu and kappa-opioid receptors), rabbit vas deferens (kappa- opioid receptors) and mouse vas deferens (delta-opioid receptors), and selective mu, delta and kappa agonists were used in the pertinent tis sues. 2. The treatment with salmon-calcitonin increased, in a dose-dep endent manner, the effect of U-50,488H in guinea pig ileum and rabbit vas deferens and the effects of [D-Pen(2), D-Pen(5)] enkephalin in mou se vas deferens. 3. The treatment with analgesic doses of salmon-calci tonin enhances the in vitro effects of kappa- and delta-opioid agonist s. The increase of the effectiveness of the opioid agonists may be one of the mechanisms involved on the analgesia induced by salmon-calcito nin.