Role Of Magnesium Lithospermate B Against Early Brain Injury Following Subarachnoid And Its Mechanism In Rats

PurposeSubarachnoid hemorrhage(SAH)is a fatal cerebrovascular disease.Previous studies have shown that magnesium lithospermate B(MLB),an effective component of salvia miltiorrhiza,has beneficial effects against neurological diseases such as ischemic stroke,Alzheimer disease.However,the role of MLB in early brain injury(EBI)post SAH is still unclear.The present study was to determine the effects of MLB on EBI following SAH and the underlying molecular mechanisms.MethodsSAH was induced by endovascular perforation in rats.Male Sprague-Dawley rats were divided into four groups at random:sham+vehicle group,SAH+vehicle group,SAH+MLB group and SAH+MLB+H89(a specific PKA inhibitor)group.After 24 h of SAH induction,mortality rate,SAH grade,neurological scores and brain water content of each group were measured and analyzed.The level of Bax,Bcl-2,cleaved capase-3,PKA,CREB and Sirtl in the cortex from each group was examined by western blot.The apoptosis of neurons in the brain was evaluated through immunofluorescence.ResultsAt 24 h after SAH,the brain water content in SAH+vehicle group increase significantly with obvious neurological deficits compared with sham+vehicle grThe Bcl-2/Bax ratio in SAH+vehicle group decreased while the expression of cleaved capase-3 and the number of TUNEL positive cells in the cortex increased.Contrary to the SAH+vehicle group,the treatment of MLB significantly decreased the brain water content in the cortex,improved the neurological functions,increased the Bcl-2/Bax ratio while decreased the expression of cleaved capase-3 and the number of TUNEL-positive cells in the cortex.Notably,MLB significantly upregulated the PKA level,the p-CREB/CREB ratio and the Sirtl expression in the brain.The preconditioning of specific PKA inhibitor H89 downregulated the levels of PKA,p-CREB/CREB ratio and sirtl expression.More importantly,H89 blocked the neuroprotective effects of MLB against SAH.ConclusionMLB treatment significantly attenuated SAH-induced EBI.These neuroprotective effects was possibly related to its regulation of the PKA/CREB/Sirtl signaling pathway and further inhibition of the neural apoptosis.MLB has become a promising method for the clinical treatment of SAH.