Activation of brown adipose tissue by a low-protein diet ameliorates hyperglycemia in a diabetic lipodystrophy mouse model.

ABSTRACT

Long-term ad libitum dietary restrictions, such as low-protein diets (LPDs), improve metabolic health and extend the life span of mice and humans. However, most studies conducted thus far have focused on the preventive effects of LPDs on metabolic syndromes. To test the therapeutic potential of LPD, we treated a lipodystrophy mouse model IRFKO (adipose-specific insulin receptor knockout) in this study. We have previously shown that IRFKO mice have profound insulin resistance, hyperglycemia, and whitening of interscapular brown adipose tissue (BAT), closely mimicking the phenotypes in lipoatrophic diabetic patients. Here, we demonstrate that 14-day of LPD (5.1% kcal from protein) feeding is sufficient to reduce postprandial blood glucose, improve insulin resistance, and normalize glucose tolerance in the IRFKO mice. This profound metabolic improvement is associated with BAT activation and increase in whole body energy expenditure. To confirm, we showed that surgical denervation of BAT attenuated the beneficial metabolic effects of LPD feeding in IRFKO mice, including the 'browning' effects on BAT and the glucose-ameliorating results. However, BAT denervation failed to affect the body weight-lowering effects of LPD. Together, our results imply a therapeutic potential to use LPD for the treatment of lipoatrophic diabetes.