Central sympathetic innervations to visceral and subcutaneous white adipose tissue

Am J Physiol Regul Integr Comp Physiol. 2014 Mar 15;306(6):R375-86. doi: 10.1152/ajpregu.00552.2013. Epub 2014 Jan 22.

Abstract

There is a link between visceral white adipose tissue (WAT) and the metabolic syndrome in humans, with health improvements produced with small visceral WAT reduction. By contrast, subcutaneous WAT provides a site for lipid storage that is rather innocuous relative to ectopic lipid storage in muscle or liver. The sympathetic nervous system (SNS) is the principal initiator for lipolysis in WAT by mammals. Nothing is known, however, about the central origins of the SNS circuitry innervating the only true visceral WAT in rodents, mesenteric WAT (MWAT), which drains into the hepatic portal vein. We tested whether the central sympathetic circuits to subcutaneous [inguinal WAT (IWAT)] and visceral WAT (MWAT) are separate or shared and whether they possess differential sympathetic drives with food deprivation in Siberian hamsters. Using two isogenic strains of pseudorabies virus, a retrograde transneuronal viral tract tracer within the same hamsters, we found some overlap (∼20-55% doubly infected neurons) between the two circuitries across the neural axis with lesser overlap proximal to the depots (spinal cord and sympathetic chain) and with more neurons involved in the innervation of IWAT than MWAT in some brain regions. Food deprivation triggered a greater sympathetic drive to subcutaneous (IWAT) than visceral (MWAT) depots. Collectively, we demonstrated both shared and separate populations of brain, spinal cord, and sympathetic chain neurons ultimately project to a subcutaneous WAT depot (IWAT) and the only visceral WAT depot in rodents (MWAT). In addition, the lipolytic stimulus of food deprivation only increased SNS drive to subcutaneous fat (IWAT).

Keywords: Siberian hamsters; food deprivation; lipolysis; norepinephrine turnover; pseudorabies virus.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adipose Tissue, White / innervation*
  • Adipose Tissue, White / metabolism
  • Adrenergic Fibers / physiology
  • Animals
  • Central Nervous System / cytology*
  • Central Nervous System / metabolism
  • Cricetinae
  • Food Deprivation / physiology*
  • Ganglia, Sympathetic / cytology*
  • Ganglia, Sympathetic / metabolism
  • Herpesvirus 1, Suid
  • Intra-Abdominal Fat / innervation*
  • Intra-Abdominal Fat / metabolism
  • Lipolysis / physiology
  • Male
  • Neuronal Tract-Tracers
  • Phodopus
  • Subcutaneous Fat / innervation*
  • Subcutaneous Fat / metabolism

Substances

  • Neuronal Tract-Tracers