Modulatory Effect of Intermittent Fasting on Autophagy and Apoptosis in White Adipose Tissue of A High Fat-Fed Rat Model

Obesity is a worldwide public health problem, with its rate being tripled in the last four decades and continuously increasing. It is linked to varied comorbidities such as diabetes, hypertension, dyslipidemia, and cardiovascular disease. Multiple rapid weight loss protocols are used nowadays to lose weight rapidly as intermittent fasting (IF). In this study, we mimic human behavior, consuming a high-fat diet pattern (HFD), then carrying out IF. We investigated the effect of HFD and IF on the visceral and subcutaneous types of white adipose tissue (WAT) morphology, autophagy and apoptosis and to evaluate any significant differences between the 2 types of WAT, with further evaluation of blood levels of Malondialdehyde (MDA) and Superoxide dismutase (SOD).
           Eighteen male rats were divided randomly into 3 groups as control group which took the basal diet, HFF fed on HFD, and IF which receive HFD accompanied by IF. Animals fasted from the 8^th week to the end of the 12^th week when all of them were sacrificed. Bodyweight was recorded, and blood was collected for measurement of serum glucose, insulin, cholesterol, triglyceride (TG), and oxidative stress markers. Both inguinal and epididymal WAT were dissected then processed and stained with H&E and immunohistochemical with antibodies for bax, LC3 and P62. Significant increase in body weight, glucose, cholesterol, TG and a significant decrease in SOD and insulin were detected in HFF but they were all significantly improved in IF except blood glucose which was not significantly decreased in IF rats. Besides a non-significant increase in MDA was recorded in HFF group. Also, hypertrophied WAT was observed especially the visceral one in HFF that decreased significantly after IF. Induced apoptosis and inhibited autophagy were recorded in HFF group and then reversed following IF protocol.  It has been proposed that IF is effective in reversing HFF effects on WAT although IF should be investigated for a longer period and followed with more strict markers.