Response of adrenal cells to parathyroid hormone stimulation

Dispersed adrenal cells of avian and bovine origin were incubated with human (h) 1-34 parathyroid hormone (PTH(1-34)), bovine (b) PTH(1-84), bPTH(3-34), avian (a) PTH, and with ACTH. Kidney tubular cells, the established target cells for PTH, were used for comparison. Cyclic AMP (cAMP) accumulation and steroid hormone (aldosterone and corticosterone) secretion were measured in response to the hormones. In the bovine adrenocortical cells PTH of both bovine and avian origin stimulated cAMP production, but the aPTH action was more pronounced. The maximal cAMP response of avian adrenocortical cells to aPTH was 15-fold greater than that of ACTH, but a 20-times higher concentration of aPTH was required to reach half-maximal response. Avian PTH stimulated steroid hormone secretion in the chick adrenocortical cells, but the induced secretion was similar to that induced by ACTH, despite the difference in cAMP accumulation. Human PTH(1-34) and bPTH(1-84), which stimulated cAMP production in kidney cells, and the conventional antagonist bPTH(3-34) inhibited aPTH stimulation of cAMP accumulation in avian adrenocortical cells, but did not interfere with ACTH action. Furthermore, cAMP stimulation by aPTH and ACTH in avian adrenal cells was additive. The results establish the adrenal as a target organ for PTH, and suggest that the PTH acts through specific receptors, distinct from those for ACTH.