Effects and Mechanism of Action of Inducible Nitric Oxide Synthase on Apoptosis in a Rat Model of Cerebral Ischemia‐Reperfusion Injury

Abstract

Inducible nitric oxide synthase (iNOS) is a key enzyme in regulating nitric oxide (NO) synthesis under stress, and NO has varying ability to regulate apoptosis. The aim of this study was to investigate the effects and possible mechanism of action of iNOS on neuronal apoptosis in a rat model of cerebral focal ischemia and reperfusion injury in rats treated with Smethylisothiourea sulfate (SMT), a high-selective inhibitor of iNOS. Seventytwo male Sprague-Dawley (SD) rats were randomly divided into three groups: the sham, middle cerebral artery occlusion (MCAO) 1 vehicle, and MCAO 1 SMT groups. Neurobehavioral deficits, infarct zone size, and cortical neuron morphology were evaluated through the modified Garcia scores, 2,3,5-triphenyltetrazolium chloride (TTC), and Nissl staining, respectively. Brain tissues and serum samples were collected at 72 hr post-reperfusion for immunohistochemical analysis, Western blotting, Terminal deoxynucleotidyl transferase-mediated dUTP-biotin Nick End Labeling assay (TUNEL) staining, and enzyme assays. The study found that inhibition of iNOS significantly attenuated the severity of the pathological changes observed as a result of ischemia-reperfusion injury: SMT reduced NO content as well as total nitric oxide synthase (tNOS) and iNOS activities in both ischemic cerebral hemisphere and serum, improved neurobehavioral scores, reduced mortality, reduced the infarct volume ratio, attenuated morphological changes in cortical neurons, decreased the rate of apoptosis (TUNEL and caspase-3-positive), and increased phospho (p)-AKT expression in ischemic penumbra. These results suggested that inhibition of iNOS might reduce the severity of ischemia-reperfusion injury by inhibiting neuronal apoptosis via maintaining p-AKT activity. Anat Rec, 299:246-255, 2016. V C 2015 Wiley Periodicals, Inc.

Comparison between the effect of human Wharton’s jelly–derived mesenchymal stem cells and levetiracetam on brain infarcts in rats

“…Peroxynitrite mediates NO-induced blood brain barrier (BBB) damage and mediate apoptotic cell death. 45 In the current study, combined use of LEV and WJ-MSCs was the most effective regimen as regard infarction volume and functional memory test. The effects of LEV and WJ-MSCs may be due to the increased expression of the neurotrophic factors BDNF, GDNF, and PEBP1 and antioxidant molecule Cu/ZnSOD in the brain tissue of treated animals, as they protect neurons from mechanisms related to ischemic insult.…”

The role of nitric oxide in stroke

“… 113 (2) The activation of iNOS induced cell apoptosis in a rat model of cerebral ischemia-reperfusion injury. 114 121 (3) Persistent hyperglycemia after ischemic stroke is associated with an excess of NO and peroxides which leads to microvascular dysfunction and poor prognosis. 115 (4) NOS leads to the damage of blood brain barrier in acute ischemic stroke.…”

Protective effects of Antrodia camphorata extract against hypoxic cell injury and ischemic stroke brain damage

“…So, the decline in the infarct volume is the sign of decreasing tissue damage. During the ischemic and inflammatory conditions, neuronal apoptosis was occurred in the presence of high iNOS content (Zheng, Ding, Wang, Zhou, & Zhang, 2016). Studies showed that iNOS increases infarct volume, stimulates inflammatory mediator's expression, and promotes iron losses from the cells (Jayaraj et al, 2019).…”