Interaction of Leptin and Amylin in the Long-Term Maintenance of Weight Loss in Diet-Induced Obese Rats

Obesity (Silver Spring). 2010 Jan;18(1):21-6. doi: 10.1038/oby.2009.187. Epub 2009 Jun 18.

Abstract

We have previously shown that combined amylin + leptin agonism elicits synergistic weight loss in diet-induced obese (DIO) rats. Here, we assessed the comparative efficacy of amylin, leptin, or amylin + leptin in the maintenance of amylin + leptin-mediated weight loss. DIO rats pretreated with the combination of rat amylin (50 microg/kg/day) and murine leptin (125 microg/kg/day) for 4 weeks were subsequently infused with either vehicle, amylin, leptin, or amylin + leptin for an additional 4 weeks. Food intake, body weight, body composition, plasma parameters, and the expression of key metabolic genes in liver and white adipose tissue (WAT) were assessed. Amylin + leptin treatment (weeks 0-4) reduced body weight to 87.5% of baseline. Rats subsequently maintained on vehicle or leptin regained all weight (to 104.2 and 101.2% of baseline, respectively), those maintained on amylin had partial weight regain (97.0%). By contrast, weight loss was largely maintained with continued amylin + leptin treatment (91.4%), associated with a 10% decrease in adiposity. Cumulative food intake (weeks 5-8) was reduced by amylin and amylin + leptin, but not by leptin alone. Amylin + leptin, but not amylin or leptin alone, reduced plasma triglycerides (by 55%), total cholesterol (by 19%), and insulin (by 57%) compared to vehicle. Amylin + leptin also reduced hepatic stearoyl-CoA desaturase-1 (Scd1) mRNA, and increased WAT mRNA levels of adiponectin, fatty acid synthase (Fasn), and lipoprotein lipase (Lpl). We conclude that, in DIO rats, maintenance of amylin + leptin-mediated weight loss requires continued treatment with both agonists, and is accompanied by sustained improvements in body composition, and indices of lipid metabolism and insulin sensitivity.

MeSH terms

  • Adiponectin / blood
  • Adipose Tissue, White / metabolism
  • Amyloid / blood
  • Amyloid / pharmacology*
  • Analysis of Variance
  • Animals
  • Appetite Depressants / pharmacology
  • Body Composition / drug effects
  • Body Weight / drug effects*
  • Diet*
  • Drug Interactions
  • Eating / drug effects
  • Gene Expression Profiling
  • Insulin / blood
  • Islet Amyloid Polypeptide
  • Leptin / blood
  • Leptin / pharmacology*
  • Liver / metabolism
  • Male
  • Obesity / drug therapy*
  • Obesity / metabolism
  • RNA, Messenger / metabolism
  • Rats
  • Weight Loss / drug effects*

Substances

  • Adiponectin
  • Amyloid
  • Appetite Depressants
  • Insulin
  • Islet Amyloid Polypeptide
  • Leptin
  • RNA, Messenger