Influence of short- and long-term treadmill exercises on levels of ghrelin, obestatin and NPY in plasma and brain extraction of obese rats.
ABSTRACT This study aims to clarify the effects of exercise on levels of appetite regulatory hormones in plasma and hypothalamus of obese rats. Diet-induced obese rats undergo short- (40 min) and long-term (40 min, 5 days/week for 8 weeks) exercises. The rats ran at a speed of 20 m/min on a 5 degrees slope treadmill. Rats undergoing short-term exercise were divided into C, E0, E1, E3, E12, and E24. Rats undergoing long-term exercise (LE) were compared to long-term control (LC). Concentrations of ghrelin, obestatin, and neuropeptide Y (NPY) were measured using radio immuno-assay. Expression of ghrelin receptor (GHSR-1a), putative obestatin receptor (GPR-39), and NPY in the hypothalamus was measured by quantitative RT-PCR. After short-term exercise, the plasma concentrations of ghrelin and obestatin were not changed, but NPY decreased. Ghrelin and obestatin in the hypothalamus decreased, and recovered 12 until 24 h. NPY increased and recovered after 24 h. Expression of GHSR-1a and NPY was not changed and GPR-39 was not observed. In LE, these changes are different in plasma and hypothalamus. It would be concluded appetite and body weight of obese rats are decreased by exercise through reduced level of ghrelin in the hypothalamus. Obestatin seems to have no effect in exercise-induced change in appetite.
SourceAvailable from: Mehdi Hedayati[Show abstract] [Hide abstract]
ABSTRACT: Introduction: 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.Iranian Journal of Endocrinology and Metabolism 01/2011; 12(6):647-655.
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ABSTRACT: Introduction: Ghrelin, produced and secreted mainly from the stomach, is a potent stimulator of growth hormone, appetite, and plays a role in energy balance control. There is increased risk of metabolic syndrome with increased LDL-C and TC levels and decreased HDL-C, with lower ghrelin concentrations. The purpose of this study was to compare the effect of different 8-week endurance training regimens on HDL-Ghrelin. Materials and Methods: Thirty Wistar male rats, 6-8 weeks of age, were randomly assigned to 3 groups of 10 rats, including two training groups with either 30 or 90 min of exercise, and a control group. Experimental groups were trained for 8 weeks, 5 days per week at 20m/min for 30 or 90 min. Rats were sacrificed 72 h after the last training session and plasma samples were collected for determining HDL-Ghrelin, HDL-C, HDL-2, HDL3, TG and TC. Analysis was performed using ANOVA and LSD post-hoc test, SPSS 16, at the alpha level of 0.05. Results: Ghrelin concentration paralleled HDL-Ghrelin changes. There was no difference in HDLGhrelin between groups. Despite reduction of TC in the training groups, no significant relationship was observed between HDL-Ghrelin and HDL2, HDL3, TG and TC. Conclusion: This study showed that isolated HDL contained Ghrelin. In addition, the 8 weeks endurance training of different durations had no correlation with HDL-Ghrelin and lipid profiles. Further studies to confirm these findings are warranted.Iranian Journal of Endocrinology and Metabolism 01/2011; 13(3):309-314.
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ABSTRACT: We used the inescapable foot shock paradigm (IFS) in rats as an animal model for post-traumatic stress disorder (PTSD). Previously we showed that exercise reversed the enhanced stress sensitivity induced by IFS. From literature it is known that food restriction has antidepressant and anxiolytic effects. Since both treatments influence energy expenditure, we questioned whether food restriction reduces anxiety in the IFS model via a comparable, NPY dependent mechanism as enrichment. Anxiety of IFS-exposed animals was measured as change in locomotion and freezing after sudden silence in an open field test, before and after two weeks of food restriction. In addition a forced swim test (FST) was performed. Next, using qPCR, the expression of neuropeptide Y (NPY) and the neuropeptide Y1 receptor (Y1 receptor) was measured in the amygdala. Food restriction increased locomotion and decreased freezing behavior both in control and IFS animals. These effects were small. IFS-induced anxiety was not abolished after two weeks of food restriction. IFS did not influence immobility or the duration of swimming in the FST of animals fed ad libitum. However, food restriction increased swimming and decreased the duration of immobility in IFS-exposed animals. Y1 receptor expression in the basolateral amygdala decreased after both IFS and food restriction. Although food restriction seems to induce a general anxiolytic effect, it does not operate via enhanced Y1 receptor expression and has no effect on the more pathogenic anxiety induced by IFS. Copyright © 2014. Published by Elsevier B.V.European Journal of Pharmacology 11/2014; 753. DOI:10.1016/j.ejphar.2014.10.060 · 2.68 Impact Factor