The effect of adrenalectomy on cocaine and amphetamine-regulated transcript (CART) expression in the hypothalamic nuclei of the rat

CART peptide is a neurotransmitter involved in various physiological proces ses including feeding, sensory processing, development, addiction, and stre ss. Substantial amounts of CART mRNA and CART peptide expression have been demonstrated in the hypothalamic periventricular area, the paraventricular nucleus of hypothalamus, the anterior lobe of the pituitary gland and the a drenal gland in addition to many other brain areas. This localization defin es the HPA axis, responsible for the stress response. The aim of the presen t study was to assess the possible mediation of the CART peptides in the st ress response by testing for changes in CART in adrenalectomized animals. T hree groups of male Sprague-Dawley rats were used for the study: sham opera ted, adrenalectomized (ADX), and ADX+hormone replacement (corticosterone, 3 0 mug/ml in drinking water/5 days). All rats were perfused 7 days after the surgery, brains were removed and serial coronal sections were prepared. Im munohistochemistry was used to assess CART peptide expression in paraventri cular and supraoptic cells. ADX lowered both the number and percentage of C ART-positive cells compared to the sham-operated group, and hormone replace ment partially restored the decrease in the CART cell numbers in ADX animal s. There were no significant changes in the supraoptic nucleus. Our results suggest a role for CART peptides in the stress response. (C) 2001 Elsevier Science BY All rights reserved.