The Role And Mechanisms Of Dihydrolipoic Acid In Early Brain Injury After Subarachnoid Hemorrhage In Rats

BackgroundSubarachnoid hemorrhage(SAH)is a devastating cerebrovascular disease with high rate of mortality and morbidity.Early brain injury(EBI),which occurs within 72 hours(h)after SAH,has recently been considered a major cause of the poor outcome of SAH patients.The underlying mechanism is complicated.Inflammation plays a significant role in EBI.Recent studies have shown that NLRP3(NACHT,LRR and PYD domains containing protein 3)inflammasome is a crucial component of the inflammatory response in EBI after SAH.Dihydrolipoic acid(DHLA)is an anti-oxidative factor.It can stabilize the lysosomal membrane,decrease oxidative stress,and exert beneficial effects in rat models of various central nervous system diseases,including SAH.However,the mechanism of the neuroprotective function of DHLA is still unclear.In this study,we investigated a role of DHLA in lysosomal rupture,NLRP3 activation,and determined the underlying pathway.MethodsSAH was induced by endovascular perforation in male Sprague-Dawley rats.DHLA was administered intraperitoneally 1 hour after SAH.Small interfering RNA(siRNA)for lysosome-associated membrane protein-1(LAMP1)and calcium/calmodulin-dependent protein kinase ??(CaMKIIa)was administered through intracerebroventricular 48 hours before SAH induction.SAH grade evaluation,short-and long-term neurological function testing,Western blot of LAMP 1,CaMKII,transforming growth factor-?-activated kinase 1(TAK1),c-Jun-N-terminal kinase(JNK),NLRP3,cleaved caspase-1 and interleukin(IL)-1? were tested.And immunofluorescence staining experiments were performed to test the colocalization of related proteins and neural cells.ResultsThe expression of LAMP 1 decreased and reached the lowest level at 24 hours after SAH.The expression of phosphorylated CaMK??(p-CaMK??)increased and reached the peak at 24 hours after SAH.And they were mainly expressed in neurons and microglia.DHLA treatment increased the expression of LAMP1 and decreased p-CaMKIIa and NLRP3 inflammasome,thereby alleviating neurological deficits after SAH.LAMP1 siRNA abolished the neuroprotective effects of DHLA and increased the level of p-CaMK??,p-TAK1,p-JNK,and NLRP3 inflammasome.CaMK?? siRNA downregulated the expression of p-TAK1,p-JNK,and NLRP3 and improved the neurobehavior after SAH.ConclusionsDHLA treatment improved neurofunction and alleviated inflammation through the LAMP1/CaMK?/TAK1 pathway in early brain injury after SAH.DHLA may provide a promising treatment to alleviate early brain injury after SAH.