Neuropeptides in interscapular and perirenal brown adipose tissue in the rat: a plurality of innervation

The occurrence of neuropeptides in rat brown adipose tissue has been investigated. Immunohistochemical studies on interscapular and perirenal brown fat have demonstrated unequivocally the presence of substance-P (SP)-like, neuropeptide-Y (NPY)-like and calcitonin gene related-peptide (CGRP)-like immunoreactive elements (putative nerves) in adventitial distribution on inter- and intralobular supply arteries and in accompanying nerve bundles. At a more peripheral level, some NPY-like immunoreactive elements and a greater number of CGRP-like immunoreactive elements were observed in the parenchymal field. Somatostatin, bombesin, neurotensin, enkephalin, and vasoactive-intestinal-polypeptide immunoreactivities were not detected. No differences in neuropeptide distribution were noted between interscapular and perirenal brown fat.