Effect of "APUD"-type hormones on osteolysis in vitro.

Besides their well-known actions, glucagon, ACTH, pentagastrin and insulin from the APUD series exert a direct action on the bone calcium content. Incubation with these substances of rat calvaria in vitro yields an evident stimulation of osteolysis with ACTH. Pentagastrin inhibits osteolysis. Glucagon and insulin inhibit parathormone-stimulated osteolysis, with no influence on the spontaneous one. Glucagon, resembling calcitonin, stimulates the 45Ca uptake from the incubation medium. The action of these substances completes the series of hormones influencing bone calcium metabolism, underlining possible interference actions of APUD-type hormones.