RELATIONSHIP BETWEEN ANTI-AVERSIVE EFFECTS OF SALMON-CALCITONIN AND PLASMA-LEVELS OF ACTH, BETA-ENDORPHIN AND PROSTAGLANDIN E(2) IN MICE

We investigated whether the anti-aversive effects of salmon calcitonin (SCT) was induced by increasing ACTH and beta-endorphin and/or by dec reasing of prostaglandin E(2) (PGE(2)) levels in plasma of mice to elu cidate the mechanisms responsible for the analgesic effects of SCT. In tracerebroventricular (i.c.v.) injections of SCT inhibited acetic acid -induced aversive behavior (writhing) in a U-shaped dose response curv e, the most effective dose being 0.1 IU/mouse. Intraperitoneal (i.p.) injections of acetic acid increased, but not significantly, the levels of plasma ACTH and PGE(2), but not beta-endorphin, which are consider ed to be psychoneuroendocrines correlated with pain. SCT (0.1 IU/mouse , i.c.v.) significantly increased plasma ACTH levels (p < 0.05) and te nded to increase beta-endorphin levels (p = 0.052) in acetic acid-trea ted mice; whereas no change in PGE(2) level was observed (p > 0.1). Th ese results suggest that the anti-aversive effects of SCT may be media ted, at least in part, by the activation of ACTH.