Physiological and pharmacological effects of melatonin at remote ischemic per conditioning protectiveness onto ischemia-reperfusion-induced necrosis in the heart

Physiological and pharmacological effects of melatonin at remote ischemic per conditioning protectiveness onto ischemia-reperfusion-induced necrosis in the heart Ischemic heart disease is the leading cause of morbidity and mortality in developed nations. In recently, it has been found that remote organ/limb temporary ischemia that renamed remote ischemic conditioning (RIC) can provide protection as an obstacle to the formation of lethal ischemic outcomes. The finding of this phenomenon can remove the requirement for direct cardiac intervention in cardiac protection. It has been shown that the cardioprotective effects of conditioning in aging, comorbidities and comedications are impaired. With aging, decreased melatonin synthesis in the pineal gland suggests that it is important in the pathogenesis of aging and aged-related cardiovascular diseases. In this study, it were investigated effects of remote ischemic perconditioning (RIPerC) and meletonin on the necrosis area, necrotic gene Cybb, hypoxia-inducible factor (HIF-1α) and inflammatory mediator nuclear factor-kappa B (NfκB) in I/R injury. Sprague Dawley rats used for this purpose were divided into 2 groups as non-pinealectomized (Non-Px) and pinealectomized (Px) groups, and waited for 2 months until I/R. They were divided into (i) Control; (ii)I/R (30 min ischemia, 120 min reperfusion caused by left coronary artery ligation); (iii)I/R+RIPerC (when myocardial ischemia initiated, 3 cycles of 5 min oclusion followed by 5 min reperfusion); (iv)I/R+Mel (10 days 10 mg/kg); (v)Px; (vi)Px+I/R; (vii)Px+I/R+RIPerC; (viii)Px+I/R+RIPerC+Melatonin groups. Hemodynamic parameters that involving ECG, blood pressure, heart rate were evaluated. The necrosis area was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining and calculated by the Image J program. Cybb, HIF-1α and NfkB was analyzed by qRT-PCR. Increased infarct size, Cybb and NfκB in I/R of Non-Px groups decreased with RIPerC and melatonin. Increased infarct size with Px was minimal with RIPerC, and significantly decreased with RIPerC+Melatonin. In both Non-Px and Px groups, RIPerC and Melatonin significantly reduced Cybb and NfκB ex- pressions. HIF-1α expression was up-regulated in the I/R and Px groups (respectively; %28-%14) when compared with the control group. Melatonin and RIPerC down-regulated (respectively; %17,6-%30,4) expression of HIF-1α. However, the data were not statistically significant. For the first time with this study, it was shown that the cardioprotection on necrosis provided by RIPerC decreased with Px. The adminstration of melatonin from the outside could reverse the protection. The physiological and pharmacological constrastions of melatonin may be important in I/R injury and in the protection of RIPerC. Anahtar Kelimeler: Remote ischemic perconditioning, melatonin, I/R, Cybb, NfκB, HIF-1α