Branched-chain amino acids, particularly
leucine, are thought to activate nutrient sensing pathways in the hypothalamus that regulate food intake and energy homeostasis. In the light of recent controversial findings of
leucine's effect on energy homeostasis further clarification of the metabolic impact of dietary
leucine supplementation is required. We examined the pharmacological and dietary effects of
leucine on energy metabolism in the Djungarian hamster (Phodopus sungorus), a well-established model for studies of alterations in
leptin sensitivity and energy metabolism. We acutely administered
leucine into the lateral ventricle (1.1 μg) of hamsters to characterize whether
leucine exhibits anorexigenic properties in this species as has been described in other rodents. Next the catabolic effect of dietary administered
leucine via supplemented rodent diet (15 %
leucine),
drinking water (17 g/
L leucine) and oral gavages (10 mg/day); as well as the effect of subcutaneously (0.1 and 3 mg/day) and intraperitoneally (0.1, 3 and 6 mg/day) injected
leucine which avoids the gastrointestinal-track was analyzed. Centrally administered
leucine reduced 24 h food intake (by 32 %) and
body weight. Both parameters were also reduced in hamsters with
leucine supplemented diet, but this catabolic response was based on a pronounced taste aversion to the
leucine-diet. In all other experiments, dietary
leucine and peripheral
injections of
leucine had no effect on food intake,
body weight and basal
blood glucose levels. Our data suggest that in the Djungarian hamster dietary
leucine fails to exhibit catabolic effects that would override the evolutionary conserved adaptations of the species which is critical for its survival.