The Role And Mechanism Of MANF In Early Brain Injury Following Experimental Subarachnoid Hemorrhage In Rats

PurposeMesencephalic astrocyte-derived neurotrophic factor(MAAF),also known as enriched arginine,is a secreted neurotrophic factor.Studies have shown that in dopaminergic neurons and other types of cells in the nervous system,MANF has a nutritional and neuroprotective effect and is believed to be beneficial in patients with Parkinson’s disease.But the specific role and mechanism are still unclear in subarachnoid hemorrhage(SAH).This study was to investigate the neuroprotective effects of MANF on early brain injury induced by SAH in rats and its related mechanisms.It is expected to understand whether MANF can be a potential therapeutic target for SAH.MethodsThe SAH model was made by modified intravascular puncture.154 male Sprague-Dawley rats were randomly divided into the following 6 groups:Sham group;SAH group;SAH + vehicle group;SAH + MANF group;SAH + MK2206 group;SAH+ MANF + MK2206 group.MANF(5 μg/5 μl 0.9%NaCl),MK2206(100 μg/5 μl DMSO)or vehicle(5 μl 0.9%NaCl or DMSO)was administered by lateral ventricle injection after subarachnoid hemorrhage.Systematic assessments were performed using a variety of methods,including mortality,Garcia trials,subarachnoid hemorrhage scores,brain water content(BWC),Western blotting,and immunofluorescence staining.ResultsCompared with the sham group,at 24 hours and 72 hours after SAH,the neurological function of the SAH group was significantly injury,and the water content in the brain tissue was significantly increased.At the same time,the expression of MANF,MMP-9,p-Akt,cleaved caspase-3 and Bax are significantly increased in the SAH group,while the expression of Bcl-2 significantly decreased;immunofluorescence showed that neuronal apoptosis significantly increased.Compared with the SAH+vehicle group,the administration of recombinant MANF significantly improved the neurological function of rats after SAH and reduced the brain water content of rats;at the same time,Stereotactic injection of rh-MANF into the cerebroventricle significantly increased the level of MANF,p-Akt,and Bcl-2 in brain tissue,whereas it down-regulated the expression of Bax,and cleaved caspase-3,which indicated that neuronal apoptosis was remarkably suppressed.Expression of matrix metallopeptidase 9(MMP-9)was also suppressed by the rh-MANF injection.The protective effect of MANF against apoptosis and blood-brain barrier(BBB)can be counteracted by administration of MK2206.ConclusionOur study shows that recombinant Mesencephalic astrocyte-derived neurotrophic factor(rh-MANF)can alleviate early brain damage after SAH.MANF can attenuate neuronal apoptosis by activating Akt-dependent pro-survival pathways and reduce blood-brain barrier damage by inhibiting MMP-9.Recombinant MANF is expected to become a potential clinical therapeutic drug.