Morin Attenuates Inflammasome-Dependent Myocardial Injury in Diabetic Rats: Modulation of the Signaling Pathway

Objective: Diabetes is a risk factor that predisposes to atherosclerotic cardiovascular diseases. The risk of myocardial infarction in diabetes is higher and this warrants investigation into exploring new drugs that can attenuate myocardial injury. In diabetes, high blood glucose levels lead to vascular inflammation which accelerates atherosclerosis. Morin, a plant flavonoid, was found effective for septic shock, cancer, cardiovascular, and renal complications and acts as an agonist for insulin secretion. This study aims to evaluate the mechanism involved in the cardioprotective action of Morin in diabetic rats. Design and method: In male Wistar rats, streptozotocin (70 mg/kg; i.p.) was administered to induce diabetes. Diabetes-confirmed rats (blood glucose >400mg/dl) were divided into 4 groups (n=8), i.e., Diabetic-control; Diabetes+Isoproterenol (ISO); Diabetes+ISO+Morin and Diabetes+Morin, in addition to this, one control group was also included in the study. Morin was orally administered at the dose of 40 mg/kg for 28 days and on the 27th and 28th day of morin administration, ISO was administered to designate groups at the dose of 85mg/kg s.c., to induce myocardial injury. After 24 hours of the second dose of ISO administration, the rat was sacrificed after collection of blood, and heart was excised to do the biochemical, histopathological and molecular investigations. Results: ROS rush following ISO administration leads to the activation of the intrinsic and extrinsic pathways of apoptosis. Morin significantly reduced oxidative stress, cardiac injury markers levels, inflammation, and apoptosis. In addition, it also reduced serum insulin and blood glucose levels. Histopathology showed cardio-protection with morin. Akt/eNOS, Nrf2/HO-1, MAPK signaling pathways, and Insulin signal transduction pathways were positively modulated by Morin pre-treatment. It also significantly modulated NLRP3 inflammasome formation. Conclusions: Morin attenuated oxidative stress and inflammation and also modified the activity of various molecular pathways to mitigate cardiomyocyte damage during ISO-induced MI in diabetic rats.