Dexamethasone rapidly increases hypothalamic neuropeptide y
secretion in adrenalectomized ob/ob mice.
Chen, Hsiao-Ling, and Dale R. Romsos.
Department of Food Science and Human Nutrition, Michigan State
University, East Lansing, MI 48824-1224
APStracts 3:0059E, 1996.
A single intracerebroventricular (icv) injection of dexamethasone
(DEX) rapidly (within 30 min) suppresses brown adipose tissue
thermogenesis and increases plasma insulin concentrations in
adrenalectomized (ADX) ob/ob mice, but not in ADX lean mice.
Neuropeptide Y (NPY) administered icv causes these same metabolic
changes within 30 min in both ADX ob/ob and lean mice. We therefore
hypothesized that DEX exerts these rapid-onset metabolic actions in
ob/ob mice via a phenotype-specific enhancement of NPY secretion
within the CNS. In support of this hypothesis DEX (a type II
glucocorticoid receptor agonist) administered icv selectively lowered
NPY concentrations in the whole hypothalamus by 35% and in the
arcuate nucleus region by 70% within 30 min, but not in the brain
stem or hippocampus, of ADX ob/ob mice, or in any of these regions of
lean mice. DEX also functioned in vitro to enhance depolarization
-dependent release of NPY from hypothalamic blocks of ADX ob/ob mice,
but not of ADX lean mice. Thus, DEX acts in the hypothalamus of ob/ob
mice in a phenotype-specific manner to evoke rapid transport of NPY
from cell bodies within the arcuate nucleus to terminal regions
including the dorsomedial and ventromedial hypothalamic regions for
release.
Received 8 November 1995; accepted in final form 1 March 1996.
APS Manuscript Number E525-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96