Ghrelin Hormone Mediates the Ameliorative Effects of Intermittent Fasting on Cardiac Dysfunctions in Experimentally Induced Thyrotoxicosis in Rats

Abstract

Cardiovascular complications of hyperthyroidism have high morbidity and mortality rates. The cardioprotective effect of intermittent fasting (IF) and the concomitant rise of blood ghrelin hormone levels during IF have gained attention, but their effects on thyrotoxic hearts are still confusing. This study was planned to investigate the impacts of IF on the hearts of rats subjected to induced thyrotoxicosis, and to spotlight the role of ghrelin hormone. For this forty-five adult male Wistar Albino rats were divided into 3 groups: control, thyrotoxic (subjected to intraperitoneal injection of L-thyroxine 100 μg/kg/day, 5 days/week for 4 weeks) and intermittent fasting-treated thyrotoxic, subjected to the same dose of L-thyroxine together with an alternate day fasting regimen for 4 weeks. Cardiac functions were assessed by in vivo studies (ECG recording and arterial blood pressure evaluation) and in-vitro studies (responses to isoproterenol infusion using Langendorff’s preparation). It was found that compared to the thyrotoxic rats, IF showed significant body weight loss and decreased left ventricular and whole heart absolute weights, with a significant decrease of heart rate and P–R interval prolongation in ECG. The baseline values of PT/LV and MFR/LV, as well as their maximal responses and delta changes in response to isoproterenol infusion, were increased and positively correlated to the ghrelin hormone. Ghrelin hormone increased in IF rats reaching the control group value and showed a positive correlation with GPX and BCL2. The data obtained suggest that IF conferred partial cardioprotective effects against moderate thyrotoxicosis. These effects were attributed at least partially to the normalization of the ghrelin hormone, which has anti-inflammatory, antioxidant and anti-apoptotic effects.