Resveratrol reduces brain injury after subarachnoid hemorrhage by inhibiting oxidative stress and endoplasmic reticulum stress

Previous studies have shown that resveratrol,a bioactive substance found in many plants,can reduce early brain injury after subarachnoid hemorrhage,but how it acts is still unclear.This study explored the mechanism using the experimental subarachnoid hemorrhage rat model established by injecting autologous blood into the cerebellomedullary cistern.Rat models were treated with an intraperitoneal injection of 60 mg/kg resveratrol 2,6,24 and 46 hours after injury.At 48 hours after injury,their neurological function was assessed using a modified Garcia score.Brain edema was measured by the wet-dry method.Neuronal apoptosis in the prefrontal cortex was detected by terminal deoxyribonucleotidyl transferase-mediated biotin-16-dUTP nick-end labeling assay.Levels of reactive oxygen species and malondialdehyde in the prefrontal cortex were determined by colorimetry.CHOP,glucose-regulated protein 78,nuclear factor-erythroid2-related factor 2 and heme oxygenase-1 mRNA expression levels in the prefrontal cortex were measured by reverse transcription polymerase chain reaction.Tumor necrosis factor-alpha content in the prefrontal cortex was detected by enzyme linked immunosorbent assay.Immunohistochemical staining was used to detect the number of positive cells of nuclear factor-erythroid 2-related factor 2,heme oxygenase 1,glucose-regulated protein 78,CHOP and glial fibrillary acidic protein.Western blot assay was utilized to analyze the expression levels of nuclear factor-erythroid 2-related factor 2,heme oxygenase 1,glucose-regulated protein 78 and CHOP protein expression levels in the prefrontal cortex.The results showed that resveratrol treatment markedly alleviated neurological deficits and brain edema in experimental subarachnoid hemorrhage rats,and reduced neuronal apoptosis in the prefrontal cortex.Resveratrol reduced the levels of reactive oxygen species and malondialdehyde,and increased the expression of nuclear factor-erythroid 2-related factor 2,heme oxygenase-1 mRNA and protein in the prefrontal cortex.Resveratrol decreased glucose-regulated protein 78,CHOP mRNA and protein expression and tumor necrosis factor-alpha level.It also activated astrocytes.The results suggest that resveratrol exerted neuroprotective effect on subarachnoid hemorrhage by reducing oxidative damage,endoplasmic reticulum stress and neuroinflammation.The study was approved by the Animals Ethics Committee of Shandong University,China on February 22,2016(approval No.LL-201602022).

Neuroprotective mechanism of L-cysteine after subarachnoid hemorrhage

Hydrogen sulfide,which can be generated in the central nervous system from the sulfhydryl-containing amino acid,L-cysteine,by cystathionine-β-synthase,may exert protective effects in experimental subarachnoid hemorrhage;however,the mechanism underlying this effect is unknown.This study explored the mechanism using a subarachnoid hemorrhage rat model induced by an endovascular perforation technique.Rats were treated with an intraperitoneal injection of 100 mM L-cysteine(30μL)30 minutes after subarachnoid hemorrhage.At 48 hours after subarachnoid hemorrhage,hematoxylin-eosin staining was used to detect changes in prefrontal cortex cells.L-cysteine significantly reduced cell edema.Neurological function was assessed using a modified Garcia score.Brain water content was measured by the wet-dry method.L-cysteine significantly reduced neurological deficits and cerebral edema after subarachnoid hemorrhage.Immunofluorescence was used to detect the number of activated microglia.Reverse transcription-polymerase chain reaction(RT-PCR)was used to detect the levels of interleukin 1β and CD86 mRNA in the prefrontal cortex.L-cysteine inhibited microglial activation in the prefrontal cortex and reduced the mRNA levels of interleukin 1βand CD86.RT-PCR and western blot analysis of the complement system showed that L-cysteine reduced expression of the complement factors,C1q,C3αand its receptor C3aR1,and the deposition of C1q in the prefrontal cortex.Dihydroethidium staining was applied to detect changes in reactive oxygen species,and immunohistochemistry was used to detect the number of NRF2-and HO-1-positive cells.L-cysteine reduced the level of reactive oxygen species in the prefrontal cortex and the number of NRF2-and HO-1-positive cells.Western blot assays and immunohistochemistry were used to detect the protein levels of CHOP and GRP78 in the prefrontal cortex and the number of CHOP-and GRP78-positive cells.L-cysteine reduced CHOP and GRP78 levels and the number of CHOP-and GRP78-positive cells.The cystathionine-β-synthase inhibitor,aminooxyacetic acid,significantly reversed the above neuroprotective effects of L-cysteine.Taken together,L-cysteine can play a neuroprotective role by regulating neuroinflammation,complement deposition,oxidative stress and endoplasmic reticulum stress.The study was approved by the Animals Ethics Committee of Shandong University,China on February 22,2016(approval No.LL-201602022).