Impact of circulating corticosterone on alpha 1- and alpha 2-noradrenergic receptors in discrete brain areas.

The impact of adrenalectomy (ADX) and subsequent corticosterone(CORT) replacement, on the binding of [3H]p-aminoclonidine to alpha 2-noradrenergic receptors and [3H]prazosin to alpha 1-noradrenergic receptors, was studied in 8 discrete hypothalamic and 5 extra-hypothalamic areas of rats. With little change in extra-hypothalamic receptors, ADX produced a large CORT-reversible decrease in alpha 2-receptor binding specifically within the hypothalamic paraventricular nucleus (PVN) and a CORT-reversible increase within the supraoptic nucleus. alpha 1-Noradrenergic receptors, in contrast, were generally unaffected by ADX. This and other evidence leads us to propose a potential modulatory influence of circulating CORT on hypothalamic alpha 2 receptors and a specific function for this CORT-alpha 2 receptor interaction specifically within the PVN, in the control of eating behavior.