Body mass, energy budget and leptin of mice under stochastic food restriction and refeeding

Periods of restricted food intake that lead to lower body weight are often followed by rapid regaining of the lost weight after ad libitum refeeding, an event generally known as the "compensatory growth". To explore the physiological mechanisms underlying "compensatory growth", we evaluated a series of energetic parameters (energy intake, energy expenditure, body composition and serum leptin levels) of adult KM mice subjected to three cycles of stochastic food restriction following by ad libitum refeeding (SFR-Re). The results indicated that animals lost their body mass after stochastic food restriction and then regained to the control level after refeeding. After the final cycle, SFR-Re mice showed higher basal metabolic rate, lower nonshivering thermogenesis, and their cytochrome c oxydase activities, as well as uncoupling protein 1(UCP1) contents of brown adipose tissue all decreased compared with controls. Meanwhile, higher energy intake and digestibility, as well as heavier fat pads also were found in SFR-Re mice. But, serum leptin levels showed no difference between SFR-Re and control mice. On the whole, these findings indicated that when food is resourceful, SFR-Re mice are under rapid "compensatory growth" by increasing their food intake and energy storage efficiency, meanwhile, decreasing energy consumption in thermogenesis. Moreover, leptin may be a possible player in the regulations of energy budget and thermogenesis during "compensatory growth".

Keywords
Body fat; Energy budget; Food restriction; Leptin; Swiss mice; Thermogenesis