Diversity of Thermogenic Capacity Predicts Divergent Obesity Susceptibility in a Wild Rodent.

OBJECTIVE: The objective of the present study was to examine whether wild rodents exhibit diverse obesity susceptibility and what factors predispose subjects to this divergence in response to a high-fat diet (HFD). METHODS: Sixty male and female Brandt's voles (Lasiopodomys brandtii) were fed an HFD for 8 weeks, and the upper (obesity prone [OP]) and lower (obesity resistant [OR]) one-third for mass gain were selected. Energy budgets and pathologic changes were measured. Another 30 males were fed a low-fat control diet (LFD) for 10 weeks and then fed an HFD for 12 weeks. The energetic parameters of the rodents on an LFD were analyzed for the correlation with body mass of the rodents on an HFD. RESULTS: OP voles had higher energy intakes, higher levels of noradrenaline-induced nonshivering thermogenesis, and a greater impairment of insulin tolerance than OR voles. Unlike laboratory rodents, there were no differences in physical activity or resting metabolic rate between these groups of voles. The thermogenic capacity during LFD feeding was the strongest predictor for mass gain during HFD feeding. CONCLUSIONS: This study suggests that a wild rodent species of Brandt's voles exhibits diverse obesity susceptibility in reaction to an HFD, providing a natural model to give insight into the mechanisms for divergent obesity susceptibility. This study also indicates that maximum thermogenic capacity has a predictive power for the development of obesity when an HFD was available.