Effect of the intraperitoneal administration of salmon-calcitonin on the “in vitro” actions of opioid agonists

Abstract

1. 1. The interaction of intraperitoneal administration of salmon-calcitonin with opioids was studied. The study was carried out using guinea pig ileum (μ and κ-opioid receptors), rabbit vas deferens (κ-opioid receptors) and mouse vas deferens (δ-opioid receptors), and selective μ, δ and κ agonists were used in the pertinent tissues. 2. 2. The treatment with salmon-calcitonin increased, in a dose-dependent 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 mouse vas deferens. 3. 3. The treatment with analgesic doses of salmon-calcitonin enhances the in vitro effects of κ- and δ-opioid agonists. The increase of the effectiveness of the opioid agonists may be one of the mechanisms involved on the analgesia induced by salmon-calcitonin.