Evidence for activation of inflammatory lipoxygenase pathways in visceral adipose tissue of obese Zucker rats

Am J Physiol Endocrinol Metab. 2011 Jan;300(1):E175-87. doi: 10.1152/ajpendo.00203.2010. Epub 2010 Oct 26.


Central obesity is associated with low-grade inflammation that promotes type 2 diabetes and cardiovascular disease in obese individuals. The 12- and 5-lipoxygenase (12-LO and 5-LO) enzymes have been linked to inflammatory changes, leading to the development of atherosclerosis. 12-LO has also been linked recently to inflammation and insulin resistance in adipocytes. We analyzed the expression of LO and proinflammatory cytokines in adipose tissue and adipocytes in obese Zucker rats, a widely studied genetic model of obesity, insulin resistance, and the metabolic syndrome. mRNA expression of 12-LO, 5-LO, and 5-LO-activating protein (FLAP) was upregulated in adipocytes and adipose tissue from obese Zucker rats compared with those from lean rats. Concomitant with increased LO gene expression, the 12-LO product 12-HETE and the 5-LO products 5-HETE and leukotriene B4 (LTB4) were also increased in adipocytes. Furthermore, upregulation of key proinflammatory markers interleukin (IL)-6, TNFα, and monocyte chemoattractant protein-1 were observed in adipocytes isolated from obese Zucker rats. Immunohistochemistry indicated that the positive 12-LO staining in adipose tissue represents cells in addition to adipocytes. This was confirmed by Western blotting in stromal vascular fractions. These changes were in part reversed by the novel anti-inflammatory drug lisofylline (LSF). LSF also reduced p-STAT4 in visceral adipose tissue from obese Zucker rats and improved the metabolic profile, reducing fasting plasma glucose and increasing insulin sensitivity in obese Zucker rats. In 3T3-L1 adipocytes, LSF abrogated the inflammatory response induced by LO products. Thus, therapeutic agents reducing LO or STAT4 activation may provide novel tools to reduce obesity-induced inflammation.

Publication types

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

MeSH terms

  • 3T3-L1 Cells
  • 5-Lipoxygenase-Activating Proteins / genetics
  • 5-Lipoxygenase-Activating Proteins / metabolism
  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology
  • Arachidonate 12-Lipoxygenase / genetics
  • Arachidonate 12-Lipoxygenase / metabolism*
  • Arachidonate 5-Lipoxygenase / genetics
  • Arachidonate 5-Lipoxygenase / metabolism*
  • Arachidonic Acids / metabolism
  • Cytokines / metabolism*
  • Female
  • Gene Expression Regulation* / drug effects
  • Inflammation Mediators / metabolism*
  • Intra-Abdominal Fat / cytology
  • Intra-Abdominal Fat / drug effects
  • Intra-Abdominal Fat / metabolism*
  • Intra-Abdominal Fat / pathology
  • Mice
  • Obesity / drug therapy
  • Obesity / metabolism*
  • Obesity / pathology
  • Obesity / physiopathology
  • Pentoxifylline / analogs & derivatives
  • Pentoxifylline / pharmacology
  • Phosphorylation / drug effects
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Zucker
  • STAT4 Transcription Factor / metabolism


  • 5-Lipoxygenase-Activating Proteins
  • Alox5ap protein, rat
  • Anti-Inflammatory Agents, Non-Steroidal
  • Arachidonic Acids
  • Cytokines
  • Inflammation Mediators
  • RNA, Messenger
  • STAT4 Transcription Factor
  • Arachidonate 12-Lipoxygenase
  • Arachidonate 5-Lipoxygenase
  • lisofylline
  • Pentoxifylline