REGULATION OF RAT ADRENAL NEUROPEPTIDE-Y (NPY) CONTENT - EFFECTS OF ACTH, DEXAMETHASONE AND HYPOPHYSECTOMY

While the presence of neuropeptide Y (NPY) in the adrenal cortex is we ll established, little is known about its regulation. In the present s tudy the involvement of the pituitary gland in the regulation of rat a drenal NPY content was investigated. Rats were subjected to one of the following treatments: hypophysectomy, sham operation, ACTH, the synth etic glucocorticoid, dexamethasone, dexamethasone plus ACTH, or saline control. The immunoreactive NPY (irNPY) content of both capsule/zona glomerulosa and inner zone/medulla fractions were estimated by radioim munoassay. Treatment with ACTH caused a significant decrease in both t he capsular/zona glomerulosa and the inner zone/medulla irNPY content compared with controls, while hypophysectomy resulted in a significant increase in adrenal irNPY. Dexamethasone treatment caused a significa nt increase in capsular irNPY, which was reversed by simultaneous admi nistration of ACTH. In the medulla, however, dexamethasone treatment s ignificantly decreased irNPY content. These results suggest that there is differential regulation of adrenal irNPY content, with irNPY in th e zona glomerulosa regulated directly by ACTH, while the irNPY content of the inner zones/medulla is regulated by glucocorticoids. (C) 1998 Elsevier Science B.V. All rights reserved.