Effects of short-term mild calorie restriction diet and renutrition with ruminant milks on leptin levels and other metabolic parameters in mice

Objective: The adaptation of an organism to a calorie-restricted diet is characterized by metabolic, endocrine, and immunologic changes. The objective of this study was to determine, in a mouse model, the changes in serum leptin levels in response to short-term mild calorie-restricted and renutrition diets using different ruminant milks. Methods: Weaned Swiss albino mice were fed with a mild calorie-restricted diet for 12 d, after which they were renourished with cow, goat, sheep, or buffalo milk for 7 d. Body, thymus, and spleen weights and biochemical, hematologic, and endocrine parameters were evaluated. Results: The mild calorie restriction did not significantly modify insulin and leptin levels. The renutrition diets increased insulin levels, being significant (P < 0.05) only when buffalo and sheep milks were used. Leptin concentrations increased in the control ad libitum (AD) group during the assayed period. After the administration of cow and goat milks, lower leptin levels were observed compared with the control AD group. All repletion diets significantly increased body, thymus, and spleen weights; however, spleen weight did not reach the values observed in the control AD group. Serum glucose and triacylglycerol levels increased after feeding with the renutrition diets. However, serum cholesterol did not increase after the renutrition period. We observed a significant decrease (P < 0.05) in the leukocyte counts in calorie-restricted mice in comparison with AD mice; after the renutrition period, the leukocyte count did not reach the values for the AD mice. Conclusion: This study suggests that a short-term change in diet with a relatively low body weight loss does not significantly affect leptin concentrations in our mouse model. However, the assayed milks could be effectively used as alternative milk sources for weight gain and for the improvement of other metabolic parameters. (C) 2009 Published by Elsevier Inc.