The Effects of Starvation and Refeeding on Oxidative Stress Parameters (MDA, SOD, GPx), Lipid Profile, Thyroid Hormones and Thyroid Histopathology in Male Wistar Rats
Objective: This study aimed to investigate the effect of starvation and re-feeding on oxidative stress markers, lipid profile, thyroid hormones, and changes in thyroid tissue and in male Wistar rats.
Method: Fifty-six male Wistar rats were divided into 6 groups. After 3 months of feeding animals with specific diet, the first group was used without fasting (day zero). Other rats were exposed to fasting for 14 days. The second group was considered as a group after fasting (day 14). In groups 3 to 6, replenishment was done and then these groups were euthanized on days 16 to 22, and blood and tissue samples were taken.
Results: Significant increase was observed in MDA, triglycerides, and VLDL cholesterol. The concentrations of SOD, GPx and T3 were decreased significantly. By re-feeding, SOD, GPx, triglycerides, total cholesterol, and VLDL cholesterol increased. T3 concentration was significantly increased in all groups after re-feeding. In thyroid tissue, the diameter of follicles and the amount of colloid decreased and the number of parafollicular cells increased during starvation. By days 2 and 4 post-refeeding there were follicles with different sizes and the numbers of parafollicular cells were increased.
Conclusion: Starvation may act on the depletion of antioxidants, predisposing subjects to oxidative injury highlights with enhanced level of MDA. Oxidative stress, may play a critical role in the pathophysiology of starvation- refeeding syndrome. Starvation results in a decrease in the serum T3 concentration due to decreased peripheral generation of T3 from T4, because carbohydrates are major regulators of T4 deiodination. The increased free fatty acid availability to the circulation and eventually to the liver contribute to increased VLDL synthesis and elevated plasma triglyceride levels after starvation. The negative effects of oxidative stress in considerable time after re-feeding should be considered in future studies.
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