Neuropeptide and noradrenaline distributions in rat interscapular brown fat and in its intact and obstructed nerves of supply

Abstract Following demonstration of noradrenergic and peptidergic nerves in rat interscapular brown adipose tissue, neuronal courses were investigated with reference to both the segmentally derived nerve traversing the fat pad and to paravascular projections, employing respectively, sucrose potassium glyoxylic acid and indirect immunofluorescence methodologies. Following ligation of the segmental nerve before its pad entry and distal to the pad, accumulations of noradrenaline, neuropeptide-Y, calcitonin gene-related peptide and substance P were observed immediately proximal to the ligature in all nerve components (T 1–5 ). Two to three days after unilateral nerve resection (proximal to the pad), with or without simultaneous contralateral padectomy, there was, in some sections of the denervated pads either total absence of, or a very sparse distribution of both noradrenergic and peptidergic labelled nerves, thus suggesting minimal paravascular projection of these nerves and a major projection via the defineable segmental nerve route.