Galanin/alpha 2-adrenoceptor interactions in telencephalic and diencephalic regions of the rat

The aim of this study was to evaluate whether galanin could affect central alpha2-adrenoceptors in telencephalic and diencephalic regions in the rat u sing quantitative receptor autoradiography with the alpha2 agonist radiolig and [H-3] p-aminoclonidine. Galanin I nM significantly and substantially in creased the K-d value of the [H-3] p-aminoclonidine binding sites in the me dial hypothalamus and amygdala by 86% (p<0.01) and 73% (p<0.05) respectivel y. The B-max value was only significantly increased with 3 nM galanin in th e amygdala and the medial hypothalamus (both p<0.05). The antagonist M35 co unteracted the increase of the K-d values of the <alpha>2-adrenoceptor agon ist binding sites produced by galanin 1 nM in the amygdala and the medial h ypothalamus (both P < 0.001). These findings suggest the existence of an an tagonistic galanin/<alpha>2 adrenoceptor interaction in the medial hypothal amus and amygdala that may be of relevance for alpha2-adrenoceptor-regulate d neuroendocrine functions and food intake. NeuroReport 12:151-155 (C) 2001 Lippincott Williams & Wilkins.