Two sympathetic nerve supplies to brown adipose tissue of the rat

Abstract

The fluorescent histochemical technique of Falck for demonstrating catecholamines in sympathetic nerve fibers was modified for use in brown fat. In normal interscapular and mediastinal brown fat, the nerve fibers surrounded the arterial Mood vessels and all parenchymal cells. Both immunosympathectomy and surgical denervation gave an almost identical histological picture of massive loss of nerves from the blood vessels only. The parenchymal innervation remained intact. The blood vessels retained single isolated nerve fibers, which were relatively more numerous on the small vessels and which were connected with the parenchymal innervation. After sympathetic nerve fibers were depleted of catecholamines by treating the rat with reserpine, the parenchymal nerves reestablished catecholamine fluorescence at a faster rate than the blood vessel nerves. Intrinsic (tissue) ganglia in the brown fat were resistant to immunosympathectomy. These ganglia contained cells which were very brightly fluorescent. These results indicate that there are two anatomically, immunologically, and pharmacologically different nerve supplies to brown fat, one to the blood vessels and the other predominantly to the parenchyma. It was concluded that the parenchymal nerve supply is derived from the intrinsic ganglia via 'short' adrenergic neurons, and the blood vessel innervation is derived from the sympathetic chain via 'long' adrenergic neurons.

Potassium‐induced increase in oxygen consumption of brown adipose tissue from the rat.

“…The paired t test (control side vs. denervated side) showed no significant differences in the amplitude of the KCl response on the two sides (P > 0-1, n = 5). This result is in agreement with those of Derry & Daniel (1970) who concluded from their fluorescence data that the nerves cut by the Sidman & Fawcett method innervate the blood vessels of the brown adipose tissue but not the adipocytes (see Discussion). In order to eliminate both the innervation of blood vessels and that of the adipocytes, four rats were chemically denervated with 6-hydroxydopamine, a drug that has been shown to destroy the sympathetic nerve endings selectively (Thoenen & Tranzer, 1968).…”

“…As shown by histofluorescence, blood vessels are more densely innervated with adrenergic nerve terminals than adipocytes, whose innervation is in fact sparse and was even thought for several years to be non-existent (Wirsen, 1964). Furthermore, this interpretation is perfectly consistent with the results of Derry & Daniel (1970); their fluorescence data showed that after surgical denervation, the innervation of the adipocytes was preserved and that of the blood vessels disappeared; they suggested that the nerves terminating on the adipocytes run close to blood vessels and are, therefore, not cut by the surgical procedure used. It can thus be inferred that the KCl effect is due to the release of noradrenaline from nerve endings that lie in close contact with the adipocytes.…”

Effects of Catecholamines on Metabolism

“…The growth of this tissue is also influenced by the sympathetic nervous system: the tissue actually grows when subjected to excessive stimulation (CAMERON and SMITH, 1964;SMITH and HORWITZ, 1969). The rich sympathetic innervation of this tissue is also unique in that it has a dual nature: cells and blood vessels are innervated by noradrenaline-containing nerves from different parts of the sympathetic nervous system (DERRY et al, 1969;DERRY and DANIEL, 1970;DANIEL and DERRY, 1969). Its vascularity is likewise very rich and the blood flow is increased by catecholamines (JANSKY and HART, 1968;HElM and HULL, 1966;KUROSHIMA et al, 1967).…”

Noradrenaline Appearance in Guinea Pig Brown Adipose Tissue

“…The development of orthosym pathetic innervation exhibits different patterns: in newborn rats, nerve catecholamine fluores cence progressively rises to reach its maximum in 15-to 20-day-old newborns (8). At this stage of development, nonshivering thermogenesis shows a maximal activation of 0 2 consumption (10).…”