In vitro TNF-α- and noradrenaline-stimulated lipolysis is impaired in adipocytes from growing rats fed a low-protein, high-carbohydrate diet

Lipids. 2013 Aug;48(8):779-86. doi: 10.1007/s11745-013-3809-z. Epub 2013 Jun 22.

Abstract

The aim of this study was to investigate tumor necrosis factor alpha (TNF-α)- and noradrenaline (NE)-stimulated lipolysis in retroperitoneal (RWAT) and epididymal (EAT) white adipose tissue as a means of understanding how low-protein, high-carbohydrate (LPHC) diet-fed rats maintain their lipid storage in a catabolic environment (marked by increases in serum TNF-α and corticosterone and sympathetic flux to RWAT and EAT), as previously observed. Adipocytes or tissues from the RWAT and EAT of rats fed an LPHC diet and rats fed a control (C) diet for 15 days were used in the experiments. The adipocytes from both tissues of the LPHC rats exhibited lower TNF-α- stimulated lipolysis compared to adipocytes from the C rats. The intracellular lipolytic agents IBMX, DBcAMPc and FSK increased lipolysis in both tissues from rats fed the C and LPHC diets compared to basal lipolysis; however, the effect was approximately 2.5-fold lower in adipocytes from LPHC rats. The LPHC diet induced a marked reduction in the β3 and α2-AR, adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) content in RWAT and EAT. The LPHC diet did not affect TNF-α receptor 1 content but did induce a reduction in ERK p44/42 in both tissues. The present work indicates that RWAT and EAT from LPHC rats have an impairment in the lipolysis signaling pathway activated by NE and TNF-α, and this impairment explains the reduced response to these lipolytic stimuli, which may be fundamental to the maintenance of lipid storage in LPHC rats.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Adipocytes / drug effects
  • Adipocytes / metabolism*
  • Adipose Tissue, White / drug effects
  • Adipose Tissue, White / growth & development
  • Adipose Tissue, White / metabolism
  • Animals
  • Body Weight / drug effects
  • Bucladesine / pharmacology
  • Diet
  • Diet, Protein-Restricted*
  • Dietary Carbohydrates / pharmacology
  • Lipase / metabolism
  • Lipolysis / drug effects
  • Lipolysis / physiology*
  • Male
  • Norepinephrine / metabolism
  • Norepinephrine / pharmacology*
  • Rats
  • Rats, Wistar
  • Receptors, Adrenergic, alpha-2 / metabolism
  • Receptors, Adrenergic, beta-3 / metabolism
  • Receptors, Tumor Necrosis Factor / metabolism
  • Sterol Esterase / metabolism
  • Tumor Necrosis Factor-alpha / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology*

Substances

  • Dietary Carbohydrates
  • Receptors, Adrenergic, alpha-2
  • Receptors, Adrenergic, beta-3
  • Receptors, Tumor Necrosis Factor
  • Tumor Necrosis Factor-alpha
  • Bucladesine
  • Sterol Esterase
  • Lipase
  • PNPLA2 protein, rat
  • 1-Methyl-3-isobutylxanthine
  • Norepinephrine