Effect of calcitonin on ACTH secretion.

We have investigated the effects of salmon calcitonin injected intracerebroventricularly on adrenocorticotropic (ACTH) secretion in rats. Salmon calcitonin was able to increase significantly (p less than 0.05) ACTH secretion at the dose of 5 ng/rat and (p less than 0.01) at the doses of 12.5, 25 and 50 ng/rat; the effect (50 ng/rat) was maximal at 30 min and still present after 60 and 120 min. The maximal dose of calcitonin produced a significant (p less than 0.05) increase in serum ACTH concentration also in stressed animals. It is suggested that calcitonin may increase serum ACTH secretion by central norepinephrine and/or 5-hydroxytryptamine pathways that regulate corticotropic releasing factor activity.