Obestatin and The Regulation of Energy Balance in Physical Activity

Obestatin, a peptide which is encoded by the same preproghrelin gene as Ghrelin, conveys information concerning the nutritional status and/or the energy stores to the central nervous system. In obese populations, circulating levels of the peptide are altered. Ghrelin, mostly acting through the GH secretagogue receptor GHS-R, is a potent GH secretagogue, an orexigenic peptide and a long-term regulator of energy homeostasis. Obestatin was described for its anorexigenic effects and it’s binding to GPR39. However recent studies do not support the role of obestatin/GPR39 system in the regulation of energy balance. Because exercise training improves the health status of obese individuals and is associated with reduction of body weight, there is growing interest in the effects of exercise on obestatin and whether this peptide may provide better understanding of how exercise improves health. Obestatin levels do not increase in response to acute exercise, and therefore obestatin does not appear to regulate growth hormone (GH) release during exercise. There is some evidence that obestatin levels do not change in plasma following resistance exercise with higher GH concentrations during exercise and decreases in tissues following chronic exercise but not in plasma. This review is focuses on obestatin, by first summarizing it function and it relationship with hormonal and metabolic changes that affect energy balance, and then discussing the effects of acute and chronic exercise on plasma and tissues obestatin concentrations, and the potential mechanisms involved.