Abstract
Diabetes mellitus (DM) is a metabolic disorder closely associated with cardiac dysfunction. Natural products are considered potential candidates for the management of DM. Crocin, a natural carotenoid derived from saffron, has been reported to possess several pharmacological properties, including cardioprotective effects. The aim of the present study was to investigate the beneficial effects of crocin on the metabolic derangement of the diabetic myocardium. Streptozotocin (STZ)-induced diabetic rats were treated with 10 mg/kg of crocin daily for two weeks. Oral administration of crocin normalized blood glucose, HbA1c, triglycerides, total cholesterol, LDL, and HDL levels. Notably, crocin reduced the elevated protein levels of cardiac PPARα and PPARδ-major transcriptional regulators of cardiac metabolism-back to normal. Consequently, the expression of the fatty acid (FA) transporter CD36 was downregulated, the activity of the FA oxidation enzyme 3-hydroxyacyl-CoA dehydrogenase (HOAD) was decreased, and intramyocardial triglyceride accumulation returned to physiological levels. Furthermore, crocin improved glucose uptake and metabolism in the diabetic myocardium, as evidenced by increased Akt phosphorylation, translocation of GLUT4 to the plasma membrane, enhanced activity of pyruvate kinase, and downregulation of pyruvate dehydrogenase kinase 4 (PDK4). Importantly, the stimulatory effect of crocin on Akt phosphorylation was also confirmed in isolated cardiac myocytes exposed to high glucose, further supporting its direct role in modulating glucose signaling pathways. Crocin treatment also reduced STZ-induced elevations in the levels of inflammatory cytokines-interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α)-as well as the phosphorylation of IκBα, bringing them close to basal levels. Overall, these findings suggest that crocin activates Akt signaling and thereby alleviates diabetes-induced metabolic disturbances by restoring the balance between glucose and fatty acid utilization in the hearts of STZ-induced diabetic rats. Therefore, crocin supplementation may represent a promising approach for the development of natural compound-based adjunct therapies for diabetic cardiomyopathy.