Nitric oxide synthase inhibition in rats: Melatonin reduces blood pressure and ischemia/reperfusion-induced infarct size

Abstract

Reduction in the synthesis or bioavailability of nitric oxide plays a significant role in the development of myocardial infarction and hypertension. Numerous studies suggest that melatonin reduces blood pressure (BP) and ischemia/reperfusion (I/R) injury in rats. The effects of melatonin on the BP and I/R-induced cardiac infarct size in L-NAME-induced hypertensive rats remains unknown. This study was designed to investigate the effects of melatonin on BP and the I/R-induced infarct size in chronic nitric oxide synthase inhibited rats by L-NAME. Rats received L-NAME for 15 days to produce hypertension and melatonin the last 5 days before I/R studies. To produce cardiac damage, the left coronary artery was occluded for 30 min, followed by 120 min reperfusion. L-NAME led to a significant increase in BP. Melatonin administration (10 mg/kg) to L-NAME treated rats significantly reduced BP and infarct size. Also, melatonin attenuated the mortality resulting from I/R, but this was not statistically significant. Melatonin administration would seem important to reduce BP and infarct size resulting from I/R in L-NAME-induced hypertensive rats.

Nitric oxide overproduction derived from inducible nitric oxide synthase increases cardiomyocyte apoptosis in human atrial fibrillation

“…NO is an endothelium-derived relaxing factor and a signaling molecule, associated with the pathogenesis of all known cardiovascular diseases, such as hypertension, viral myocarditis, myocardial infarction, and heart failure [15,20,21]. Minamino et al [22] were the first to show that the plasma levels of NO X decreased significantly in AF patients.…”

Role of melatonin in metabolic regulation

“…In the same model of hypertension, melatonin, in addition to lowering mean BP and causing a heart rate reduction, restored plasma norepinephrine concentration and the proportion of β1/β2 receptors in the heart [51], enhanced maximal relaxation of mesenteric arteries [52] and improved baroreflex responses [53]. Similarly, in rats with nitric oxide-deficient hypertension, 5-day treatment with melatonin (10 mg/kg) reduced BP and ischemiareperfusion injury of myocardial tissue [54].…”

Protective effects of melatonin and glucagon‐like peptide‐1 receptor agonist (liraglutide) on gastric ischaemia–reperfusion injury in high‐fat/sucrose‐fed rats

“…Group III (SCD + melatonin) . Standard chow diet‐fed rats were treated with melatonin at a dose of 10 mg/kg per day orally for 4 weeks before the induction of GI–R …”