Experimental Study The Neuroprotective Role Of Cystatin C And The Relevance To Autophagy On Early Brain Injury After Subarachnoid Hemorrhage In Rats

Objective:To study the effect of Cystatin C on earlier injured brain after subarachnoidhemorrhage and the effect of Cystatin C on autophagy after subarachnoid hemorrhage.Methods:48health male Sprague-dawley(SD) rats were assigned randomly into followinggroups: sham operation group(n=8), SAH group(n=8), vehicle group(n=8)，Cystatin Cgroup(Cystatin C group was assigned into three subgroups according to the concentrationof Cystatin C (the low concentration Cystatin C group (2mg/L)、the medium concentrationCystatin Cgroup (5mg/L)、the high concentration Cystatin C group (10mg/L),every subgroupn=8).All SAH animals were subjected to injection of autologous arterial blood intoprechiasmatic cistern.The nerve functional scoring after experimental SAH were observed;Cerebral edema were measured by dry-wet weight method and blood-brain barrierpermeability were detected with IgG antibody byimmunohistochemistry;Microtubule-associated protein light chain-3(LC3)and beclin-1were investigated by Western blot analysis and immunohistochemistry.Pathologic changeautophagic double membrane structure were observed by transmission electronicmicroscope at48h after experimental SAH.Results:As compared with sham operation group,nerve behavior function impairment、cerebral edema aggravate and increase of IgG content in rats cortical neurons caused bySAH was evident in SAH subjects(P<0.05).There was no obvious difference amongvehicle group and SAH group(P>0.05).The low concentration Cystatin C and the medium concentration Cystatin C treated rats showed better nerve behavior performance、lightercerebral edema and less IgG content in the brain tissue than SAH group rats at48h afterSAH(P<0.05).However,there was no obvious difference among high concentrationCystatin C group and SAH group(P>0.05).As compared with sham operation group,LC3and Beclin-1proteins began to elevatein SAH group and vehicle group at48h after SAH(P<0.05). There was no obviousdifference among vehicle group and SAH group(P>0.05).LC3and Beclin-1proteins inCystatin C group elevate obviously compared with SAH group(P<0.05).The intensity ofautophagy was paralleled with the concentration of Cystatin C.Electron microscopically,there was no obvious damage in the rats cortical neurons ofsham group.Less damaged nerve cells were found in the rats cortical neurons in Cystatin Cgroup with low concentration and medium concentration treatmented than the SAH ratscortical neurons.There was a marked increase in autophagosomes and autolysosomes inneurons in Cystatin C groups.There was also obvious damage in the rats cortical neuronsof the high concentration Cystatin C.Conclusions:1、Cystatin C plays a protective role on early brain injury after SAH.2、Cystatin C with certain concentrations may play a protective role on early braininjury after SAH.However,the high concentration Cystatin C show no protective effect onearly brain injury after SAH.3、Autophagy pathway is induced by Cystatin C after SAH and the intensity ofautophagy after SAH was paralleled with the concentration of Cystatin C after Cystatin Ctreatmented.