Blunted metabolic response to fasting in obese mice.

The aim of the study was to evaluate metabolic changes in response to fasting in normal and obese mice. C57BL6 and obese (diet-induced obesity (DIO) and ob/ob) mice were used in this study. They were fasted for 24 h and re-fed for 24 h. Body weight was monitored before, after fasting and during re-feeding (2 and 24 h after re-feeding). Food intake was measured 2 and 24 h after re-feeding began. Blood samples were taken before and after 24 h fasting. As metabolic parameters, blood glucose, plasma insulin, ghrelin levels and oxygen consumption were measured. Blood glucose and plasma insulin levels in DIO and ob/ob mice were higher than normal mice, and plasma ghrelin levels were lower in DIO and ob/ob mice. There was reduced body weight loss in DIO mice than in normal mice for 24 h fasting. When they were re-fed, DIO and ob/ob mice consumed less food intake than normal mice. Twenty-four hours food deprivation induced significantly smaller plasma ghrelin elevation in these obese mice. Fasting-induced decrease in oxygen consumption was significantly smaller in DIO and ob/ob mice than normal mice. This data show that obese mice may have decreased sensitivity to fasting-induced increase in circulating ghrelin and their oxygen consumption exhibited a blunted response to fasting.