Catecholaminergic and peptidergic nerves in naturally occurring and pheochromocytoma-associated human brown adipose tissue

Noradrenergic and peptidergic innervations in naturally occurring and pheochromocytoma‐associated human perirenal brown adipose tissue were demonstrated. The presence of both parenchymal and periarterial noradrenergic nerve plexuses was revealed by the sucrose‐potassium‐glyoxylic‐acid (SPG) technique in all tissue samples. Immunohistochemical studies also indicated the presence of neuropeptide Y‐like, calcitonin gene‐related peptidelike, substance P‐like, and bombesinlike immunoreactive nerves in the adventitia of both inter‐ and intralobular arteries. At a more peripheral level, only neuropeptide Y‐like immunoreactive elements were observed in the parenchymal field. No somatostatinlike or enkephalinlike immunoreactivity was detected. The specific distributions of noradrenergic and peptidergic nerves were similar in both naturally occurring and pheochromocytoma‐associated brown adipose tissue. Thus these findings indicate a plurality of innervation in human perirenal brown fat.