Effect Of Moderate Perinatal Ethanol Exposure On Stroke And Neuroprotection And Mechanisms Of Icariin

Ischemic stroke is the most common cerebrovascular disease in China, causing enormous social and family costs. Studies have reported that perinatal environmental factors can alter susceptibility to ischemic stroke later in life. The survey showed the proportion of moderate alcohol consumption among pregnant women is about 10%. Few studies have examined the effects of moderate alcohol intake by pregnant women or animals on the developing brain and its consequences later in life. We would evaluate whether moderate EtOH exposure in the perinatal period alone or combined with exposure in adulthood increases ischemic sensitivity in a sex-specific manner in adult brain. Currently, there are less neuroprotectants for ischemic injury in clinic. Recent studies suggest that icariin has protective effects against oxygen and glucose deprivation (OGD)-mediated injury in primary cultured cerebral cortical neurons of Wistar rats. However, the underlying mechanism of the neuroprotection of icariin remains unclear. We investigate if icariin exerts neuroprotective effect by regulating SIRT1, MAPK signaling pathway and the antioxidant catalase (CAT) and peroxiredoxin-1(Prx1).Purpose:1) To assess whether moderate EtOH exposure in the perinatal period alone or combined with exposure in adulthood increases ischemic sensitivity in a sex-specific manner in adult brain.2) To explore the possible mechanisms of neuroprotective effect by icariin.Methods:1) We developed a model of perinatal moderate EtOH exposure in C57BL/6 mice and determined the EtOH dose of adult moderate alcohol consumption in C57BL/6 mice based on blood EtOH concentrations (BECs); mice were treated with middle cerebral artery occlusion (MCAO); Kunming mice primary cultured neurons were subjected to OGD model and H2O2 models.2) Infarct volumes were measured by TTC staining, serum sex hormones were measured by radioimmunoassay and neuronal cell death was assayed by MTT, FACS and so on.3) Molecular mechanisms were explored with techniques such as real-time PCR and Western Blot.Results:1) In adult mice when EtOH exposure was limited to only the perinatal period, cortical and striatal infarct volumes after 1 h MCAO and 72 h reperfusion were comparable among the groups regardless of sex (male vs. female) or perinatal treatment (EtOH vs. saline).2) In adult mice exposed to moderate EtOH perinatally and in adulthood, EtOH had no effect on cortical infarct volumes compared to saline in both males and females. However, in striatum, EtOH exposure increased male, but not female, striatal ischemic injury.3) There were no differences in serum levels of sex hormones 72 hours after MCAO in adult mice with moderate EtOH exposure in the perinatal period alone or combined with exposure in adulthood as compared to saline exposed mice.4) Icariin increased the cell viability after OGD in a time and dose-dependent manner.5) Icariin could enhance the mRNA and protein expression of SIRT1.6) The neuroprotective effect of icariin was related to the activation of MAPK/P38. P38 inhibitor SB203580 could suppresse the increase of SIRT1 induced by icariin.7) Icariin increased neuronal viability after H2O2 treatment and decreased production of oxidative stress in H2O2-treated neurons.8) Icariin promoted catalase mRNA level and catalase activity, and enhanced the mRNA and protein expression of Prxl.9) Icariin improved the protein levels of SIRT1 in H2O2-treated neurons. The SIRT1 inhibitor III could partly suppress the effect of icariin on CAT and Prx1, thus block its neuroprotective effect in H2O2-treated neurons.Conclusion:1) Moderate EtOH exposure during the perinatal period did not alter cortical and striatal infarct volumes following experimental stroke in adult male or female mice.2) Moderate EtOH exposure during the perinatal period and in adulthood collectively increased striatal infarct volume following experimental stroke only in adult male mice.3) Icariin protected primary cultured neurons against OGD and H2O2 treatment.4) Icariin exerted its neuroprotective effect by up-regulating the expression of SIRT1 through MAPK/P38 activation.5) Icariin suppressed oxidative stress neuropathology by up-regulating CAT/Prx1 which was possibly dependent on the enhancement of SIRT1.