Hypothalamic a‐MSH is increased in male rats fed a high soy protein diet

Abstract

The hypothalamus is actively involved in energy homeostasis, including food intake regulation. Increased activity of the melanocortin system within the mediobasal hypothalamus (MBH) may facilitate reduced food intake. The effectiveness of high protein diets in weight loss may be through an increase in satiety. The objective of this study was to characterize changes in the hypothalamic melanocortin system in the MBH of male Sprague‐Dawley rats fed a high protein diet (HP; 50% protein: 34% CHO: 16% fat) versus an adequate protein diet (C; 15:69:16). The concentration of a‐melanocyte stimulating hormone (a‐MSH), a known anorexigenic neuropeptide in the MBH, was determined following 10 days on the high protein diet. The whole brain was removed, snap‐frozen in ice‐cold isopentane and stored for analysis. The MBH was dissected out, homogenized and a‐MSH levels measured by RIA. Animals on the HP diet consumed an average of 77.9 ± 2.5 kcal/d, 12.4 ± 3.8 kcal/d less than the control (p < 0.01) and α‐MSH was 15.2 ± 1.0 pg/mg protein in animals on the HP diet, 3.0 ± 1.3 pg/mg higher than control (p < 0.05). Increased levels of a‐MSH in the MBH of rats chronically fed the HP diet are consistent with increased satiety and subsequent reduced food intakes as compared to their low‐protein‐fed counterparts. Supported by APS Porter Physiology Fellowship Award.