Calcitonin directly increases adrenocorticotropic hormone-stimulated corticosterone production in the hen adrenal gland

The present study was performed to elu- cidate whether the receptor for calcitonin (CT) exists in the adrenocortical cells of hens and to determine the effect of CT on adrenocorticotropic hormone (ACTH)- stimulated corticosterone production in its cell. The binding site of CT in the membrane fraction of the adrenal gland in hens was determined using a ( 125 I)CT binding assay system. The binding properties in the adrenal gland satisfied the criteria of a receptor-ligand interaction in terms of specificity, reversibility, and sat- uration. When the cortical cells were incubated in vitro with chicken ACTH in the presence of CT, greater cor- ticosterone production was observed. The result sug- gested that CT acts directly on the adrenocortical cells via its receptor binding and increases responsiveness of ACTH on corticosterone production in the laying hen.