Denervation as a tool for testing sympathetic control of white adipose tissue

Abstract

This review summarizes the evidence derived from studies utilizing denervation procedures to demonstrate sympathetic control of white adipose tissue metabolism and body fat mass. A majority of the work demonstrating neural control of white fat was performed in the Bartness laboratory with Siberian hamsters as the predominant experimental model. These animals experience dramatic changes in body fat mass in response to changes in photoperiod, however, the mechanisms identified in hamsters have been reproduced or further elucidated by experiments with other animal models. Evidence for the role of sympathetic innervation contributing to the control of white adipocyte lipolysis and preadipocyte proliferation is summarized. In addition, evidence from denervation experiments for neural communication between different white fat depots as well as for a feedback control loop between sensory afferents from individual fat depots and sympathetic efferents to the same or distant white fat depots is discussed.

Keywords: Adipocyte lipolysis; Leptin; Preadipocyte proliferation; Sympathectomy.

Figure 1

Schematic representation of sympathetic and sensory innervation of white adipose tissue and the response to selective sympathetic or sensory denervation. Sympathetic denervation of one pad results in an enlargement of the denervated pad due to a decrease in lipolysis, which allows enlargement of existing cells, and an increase in fat cell number. Distant fat depots enlarge due to a decrease in lipolysis, but no change in fat cell number. Sensory denervation of one fat pad results in a reduction in sympathetic drive to multiple fat pads which increases lipolysis and increases fat cell size.