Neuroprotective MK801 is associated with nitric oxide synthase during hypoxia/reoxygenation in rat cortical cell cultures

Abstract

The neuroprotective effect of MK801 against hypoxia and/or reoxygenation-induced neuronal cell injury and its relationship to neuronal nitric oxide synthetase (nNOS) expression were examined in cultured rat cortical cells. Treatment of cortical neuronal cells with hypoxia (95% N(2)/5% CO(2)) for 2 h followed by reoxygenation for 24 h induced a release of lactate dehydrogenase (LDH) into the medium, and reduced the protein level of MAP-2 as well. MK801 attenuated the release of LDH and the reduction of the MAP-2 protein by hypoxia, suggesting a neuroprotective role of MK801. MK801 also diminished the number of nuclear condensation by hypoxia/reoxygenation. The NOS inhibitors 7-nitroindazole (7-NI) and N (G)-nitro-L-arginine methyl ester (L-NAME), as well as the Ca(2+) channel blocker nimodipine, reduced hypoxia-induced LDH, suggesting that nitric oxide (NO) and calcium homeostasis contribute to hypoxia and/or the reoxygenation-induced cell injury. The levels of nNOS immunoactivities and mRNA by RT-PCR were enhanced by hypoxia with time and, down regulated following 24 h reoxygenation after hypoxia, and were attenuated by MK801. In addition, the reduction of nNOS mRNA levels by hypoxia/reoxygenation was also diminished by MK801. Further delineation of the mechanisms of NO production and nNOS regulation are needed and may lead to additional strategies to protect neuronal cells against hypoxic/reoxygenation insults.

Bcl‐2 prevents hypoxia/reoxygenation‐induced cell death through suppressed generation of reactive oxygen species and upregulation of Bcl‐2 proteins

“…It is well known that Bcl-2 prevents apoptosis, and many studies suggest that H/R-induced cell death is associated with apoptosis [Huang et al, 2002;Li et al, 2002a]. Then, we investigated the activation of caspases and the loss of Dc in order to prove that apoptosis participates in H/Rinduced cell death.…”

“…Post-hypoxic reoxygenation (H/R) is important in human pathophysiology because it occurs in a wide variety of vital clinical conditions such as circulatory shock, myocardial ischemia, stroke, and transplantation of organs [Robin and Theodore, 1982;McCord, 1985;Levinson et al, 1986]. Numerous studies have implicated ROS as playing an important role in the pathogenesis of H/R injury, and ROS has been implicated in apoptosis after H/R [Huang et al, 2002;Li et al, 2002a]. Cellular models of H/R have provided useful tools for the study of ROS-mediated mechanisms of cellular dysfunction [Watkins et al, 1995].…”

Neuronal NOS activation during oxygen and glucose deprivation triggers cerebellar granule cell death in the later reoxygenation phase

“…The temporal relationship between nNOS activity and expression and development of neuronal damage elicited by anoxia and reoxygenation remains unclear. Indeed, it is not yet known whether the activation of nNOS triggered during oxygen and glucose deprivation (OGD) persists during the reoxygenation phase, thus causing cellular damage at the end of this period (Huang et al, 2002). Secondly, it remains uncertain whether inhibition of nNOS activation during OGD is sufficient to prevent cell damage in the later reoxygenation period or whether prolonged inhibition is required to generate a neuroprotective effect.…”

“…Neuronal nitric oxide synthase (nNOS), the Ca 2ϩ -dependent and constitutive isoform of NOS, sets off a chain of intracellular events that leads to cell injury during anoxia and reoxygenation conditions (Huang et al, 2002, Yamamoto et al, 2003. The temporal relationship between nNOS activity and expression and development of neuronal damage elicited by anoxia and reoxygenation remains unclear.…”

Involvement of the nitric oxide/protein kinase G pathway in polychlorinated biphenyl‐induced cell death in SH‐SY 5Y neuroblastoma cells

“…A possible downstream effect of [Ca 2+ ] i increase is the activation of neuronal nitric oxide synthase (nNOS), the Ca 2+ -dependent and constitutive isoform of NOS that is known to set off the chain of intracellular events leading to neuronal injury during exposure to different toxic stimuli, such as oxygen and glucose deprivation and reoxygenation (Huang et al, 2002;Yamamoto et al, 2003;Scorziello et al, 2004) and gp 120, a human immunodeficiency virus-1 coat protein (Corasaniti et al, 1995).…”