Modulating fibroblast growth factor 21 in hyperphagic OLETF rats with daily exercise and caloric restriction

Appl Physiol Nutr Metab. 2012 Dec;37(6):1054-62. doi: 10.1139/h2012-091. Epub 2012 Aug 15.

Abstract

Chronic treatment with fibroblast growth factor 21 (FGF-21) favorably improves obesity and nonalcoholic fatty liver disease (NAFLD) outcomes; however, FGF-21 expression is paradoxically elevated in obese conditions. Here, we sought to determine the effects of obesity prevention by daily exercise (EX) vs. caloric restriction (CR) on hepatic FGF-21 in the hyperphagic, Otsuka Long-Evans Tokushima Fatty (OLETF) rat. Four-week-old male OLETF rats were randomized into groups (n = 7-8 per group) of ad libitum fed, sedentary (OLETF-SED), voluntary wheel running exercise (OLETF-EX), or CR (OLETF-CR; 70% of SED) until 40 weeks of age. Nonhyperphagic, Long-Evans Tokushima Otsuka (LETO-SED) rats served as controls. Both daily EX and CR prevented obesity and NAFLD development observed in the OLETF-SED animals. This was associated with significantly (p < 0.01) lower serum FGF-21 (~80% lower) and hepatic FGF-21 mRNA expression (~65% lower) in the OLETF-EX and OLETF-CR rats compared with the OLETF-SED rats. However, hepatic FGF-21 protein content was reduced to the greatest extent in the OLETF-EX animals (50% of OLETF-SED) and did not differ between the OLETF-SED and OLETF-CR rats. Hepatic FGF-21 signaling mediators - hepatic FGF-21 receptor 2 (FGFR2, mRNA expression), hepatic FGF-21 receptor substrate 2 (FRS2, protein content), and co-receptor β-Klotho (protein content) - were all elevated (60%-100%, ~40%, and +30%-50%, respectively) in the OLETF-EX and OLETF-CR animals compared with the OLETF-SED animals. Daily exercise and caloric restriction modulate hepatic FGF-21 and its primary signaling mediators in the hyperphagic OLETF rat. Enhanced metabolic action of FGF-21 may partially explain the benefits of exercise and caloric restriction on NAFLD outcomes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caloric Restriction*
  • Fibroblast Growth Factors / analysis*
  • Fibroblast Growth Factors / physiology
  • Hyperphagia / complications*
  • Liver / chemistry*
  • Liver / metabolism
  • Male
  • Obesity / etiology
  • Obesity / metabolism
  • Obesity / prevention & control*
  • Physical Exertion / physiology*
  • RNA, Messenger / analysis
  • Rats
  • Rats, Inbred OLETF
  • Receptors, Fibroblast Growth Factor / genetics

Substances

  • RNA, Messenger
  • Receptors, Fibroblast Growth Factor
  • fibroblast growth factor 21
  • Fibroblast Growth Factors