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

Cardiovascular complications of hyperthyroidism have highmorbidity and mortality rates. The cardioprotective effect of intermittentfasting (IF) and the concomitant rise of blood ghrelin hormone levelsduring IF have gained attention, but their effects on thyrotoxichearts are still confusing. This study was planned to investigatethe impacts of IF on the hearts of rats subjected to induced thyrotoxicosis,and to spotlight the role of ghrelin hormone. For this forty-fiveadult male Wistar Albino rats were divided into 3 groups: control,thyrotoxic (subjected to intraperitoneal injection of L-thyroxine100 μg/kg/day, 5 days/week for 4 weeks) and intermittent fasting-treatedthyrotoxic, subjected to the same dose of L-thyroxine together withan alternate day fasting regimen for 4 weeks. Cardiac functionswere assessed by in vivo studies (ECG recording and arterial bloodpressure evaluation) and in-vitro studies (responses to isoproterenolinfusion using Langendorff’s preparation). It was found that comparedto the thyrotoxic rats, IF showed significant body weight loss anddecreased left ventricular and whole heart absolute weights, witha significant decrease of heart rate and P–R interval prolongationin ECG. The baseline values of PT/LV and MFR/LV, as well as theirmaximal responses and delta changes in response to isoproterenolinfusion, were increased and positively correlated to the ghrelinhormone. Ghrelin hormone increased in IF rats reaching the controlgroup value and showed a positive correlation with GPX and BCL2.The data obtained suggest that IF conferred partial cardioprotectiveeffects against moderate thyrotoxicosis. These effects were attributedat least partially to the normalization of the ghrelin hormone,which has anti-inflammatory, antioxidant and anti-apoptotic effects.