Effects of random food deprivation on body mass, behavior and serum leptin levels in Eothenomys miletus (Mammalia: Rodentia: Cricetidae)

Abstract

The value of phenotypic plasticity in energy metabolism and behavioral patterns in response to variations of food availability was handled in adult male voles (Eothenomys miletus) acclimated to random food deprivation (FD) for 4 weeks. During this period, in which voles were fed ad libitum for a randomly assigned 3 days each week, changes in body mass, food intake, resting metabolic rate (RMR), non-shivering thermogenesis (NST) and serum leptin levels were measured. Behavioral observations were made to examine behavioral patterns including activity, feeding, grooming and resting behaviors. The results showed that food intake and gastrointestinal mass increased significantly, but RMR and NST decreased significantly in the FD group compared to the control group. Moreover, the FD group had a significantly higher percentage of feeding behavior and lower activity than those in control group. In addition, serum leptin levels were positively correlated with body fat mass, but showed no significant differences between FD and the control group. These results suggest that E. miletus can compensate for an unpredictable reduction of food availability by engaging in an energetic strategy related to food intake and a decrease in energy expenditure associated with RMR, NST plus general activity, together with the mobilization of body fat as well as the adjustment of the gastrointestinal tract, which consequently play an important role in adaptations to food shortage in unpredictable environments.