Effect of Physical Exercise or Apelin on Metabolic Syndrome in Rats

Background: Apelin is an adipokine and also a myokine likely to be involved in whole body metabolic adaptive changes that occur in response to regular exercise. Aim: Is to study the effect of exercise induced apelin release or exogenous apelin on high fat diet/sucrose (HFD/ sucrose) induced Metabolic Syndrome (MS). Material and Methods: 40 male wistar albino rats of local strain weighing 130-180gm were subdivided into 4 equal groups: Control, HFD/sucrose, HFD/sucrose + exercise and HFD/sucrose + apelin-13. At the end of the experiment (after 12 weeks), Body Mass Index (BMI), systolic Blood Pressure (sBP), serum [fasting glucose, glycosylated hemoglobin (HbA1c), fasting insulin, homeostatic model assessment of insulin resistance and sensitivity (HOMA-IR and HOMA-S), Free Fatty Acids (FFA) and Triglycerides (TG), Malondialdehyde (MDA) and total nitrite/nitrate (NOx)] and total thiol (T-SH) in muscle tissue and plasma [tumor necrosis factor alpha (TNF-a) and apelin level]. Pearson correlation coefficient between plasma apelin and (BMI, fasting insulin, HOMA-S and TG) were also done along all groups. Results: 12 week HFD/sucrose produced typical picture of MS. Combination of HFD sucrose with either exercise or exogenous administration of apelin produced significant improvement of all parameters in comparison to untreated HFD/sucrose group. Interestingly, no significant difference in all parameters between exercise and apelin-treated groups with the exception of a significant reduction in BMI in exercise group compared to apelin-treated group. The increase of plasma apelin by either exercise or apelin treated groups was about 3 folds in comparison to untreated HFD/sucrose group. Significant negative correlation was found between apelin and both (fasting insulin and TG) and significant positive correlation with (HOMA-S) along all groups and significant negative correlation with BMI only in exercise treated group. Conclusion: Apelin could be regarded as an exerciseinduced endocrine activator with multiple beneficial effects through adipocytes and may serve as a novel therapeutic target for metabolic syndrome (obesity and/or type 2 diabetes).