CIRCULATING NEUROPEPTIDE-Y (NPY) AND CATECHOLAMINES IN RAT UNDER RESTING AND STRESS CONDITIONS - ARGUMENTS FOR EXTRAADRENAL ORIGIN OF NPY, ADRENAL AND EXTRAADRENAL SOURCES OF CATECHOLAMINES

Neuropeptide Y (NPY) is found in cell bodies of neurons in the brain a nd co-localized with noradrenaline (NA) in sympathetic nerves as well as with NA and adrenaline (A) in the adrenal chromaffin cells. The pur pose of the present work is to determine whether NPY and catecholamine s found in the plasma of the rat under resting and stress conditions ( ether inhalation, restraint) arise from the adrenals or from extra-adr enal sites. We used adrenalectomized (adx) rats and sham-adx ones. Adr enalectomy increased plasma adrenocorticotrophic hormone (ACTH) levels but decreased drastically circulating corticosterone (B) and A (-97%) . However, resting NA was slightly but not significantly decreased and NPY not affected. Ether inhalation (3 min) increased plasma levels of ACTH, B, NA and A in sham-adx rats, ACTH, NA and, weakly, A in adx on es. Restraint (30 min) increased B, NA and A in sham-adx rats, NA and, poorly, A, in adx ones. In contrast, plasma levels of NPY were not si gnificantly affected by these stress conditions. The present data sugg est that NA found in rat plasma at rest and during ether or restraint stress could arise from both adrenal medulla and noradrenergic nerve e ndings while A arises mainly from the adrenergic chromaffin cells of t he adrenals. In contrast, NPY found in the circulation, at rest and un der stress conditions, is not derived from the adrenals but emanates m ainly from an extra-adrenal source. (C) 1998 Elsevier Science Ireland Ltd. Ail rights reserved.