Poster Sessions

ENDO -6

Masaru Honda

M. Honda, E. Sanchez-Lemus, Y. Murakami, J. M. Saavedra

Brain, pituitary and adrenal Angiotensin II AT1 receptor subtypes participate in the response to restraint and immobilization stress

We wished to determine, in rat models of acute restraint and immobilization stress, the effect of three days s.c. administration of ARB candesartan (1mg/kg/day) on the HPA axis response and on the expression of Ang II receptors. We found increased plasma corticosterone, ACTH and aldosterone concentrations after both stress, and higher plasma ACTH concentrations after immobilization than restraint stress. Candesartan did not prevent these increases. Candesartan inhibited AT1 receptor binding in all brain areas studied, including the PVN. Candesartan prevented the AT1A mRNA upregulation produced by restraint stress, but was ineffective in immobilization stress. In the pituitary gland, significant AT1A mRNA increase and AT1B mRNA decrease were observed after immobilization stress. In adrenal zona glomerulosa, not only both stress but also candesartan decreased AT1 binding and AT1B mRNA. In adrenal medulla, candesartan did not prevent AT1A and tyrosine hydroxylase mRNA increase after both stress. In conclusion, our results implicate Ang II AT1 receptors in the PVN, pituitary and adrenal gland in the regulation of the response to psychological and physiological stress. There is a differential response of AT1 receptor subtypes during stress. The effectiveness of these compounds may depend on the stress type, intensity and duration