Neuroprotection by Regulating the mBDNF/proBDNF Ratio after Cerebral Intracerebral Hemorrhage Is Affected by ATP Administration Through P2X4 r/P38-MAPK/Ca <sup>2+</sup>/SNAREs Regulation

Abstract

Background: Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a pivotal role in neuronal development by modulating synaptic activity and regeneration. BDNF has two forms, the mature BDNF (mBDNF) and the precursor BDNF (proBDNF), which seem to act in opposite functional ways. The involvement of mBDNF/proBDNF ratio and its role after cerebral intracerebral hemorrhage (ICH) are not fully characterized yet. Methods: To address these issues, adenosine 5′-triphosphate disodium salt hydrate (ATP), a P2 purine agonist that evokes the release of mBDNF, was administrated to regulate mBDNF/proBDNF ratio. Data was evidenced by hematoma volume, neurological scores, edema or blood-brain barrier disruption, HE, Nissl staining and immunofluorescence. To investigate the regulation mechanism of mBDNF/proBDNF ratio by ATP, we used P2X4r LEN, P38-mitogen activated protein kinase (MAPK), Ca2+, and soluble N-ethylmaleimide-sensitive factor attachment receptors (SNAREs) inhibitor. Findings: ATP promoted mBDNF/proBDNF ratio and protected against ICH injury including a reduction in hematoma volume, an increase in neurological scores, alleviation of edema or blood-brain barrier disruption, and an improvement in outcomes of HE, Nissl staining, and immunofluorescence. In addition, the ratio of mBDNF/proBDNF was mediated by P2X4r primarily, and then regulated by ATP-induced activation of P38-MAPK, dependent upon the presence of extracellular and endoplasmic reticulum store Ca2+ and related to SNARE-mediated exocytosis. Interpretation: Our study demonstrates that the mBDNF/proBDNF ratio is able to alleviate ICH injury by ATP administration through P2X4 receptor/P38-MAPK/Ca2+/SNAREs regulation. These results may provide a new strategy to alleviate ICH injury by promoting the mBDNF/proBDNF ratio in neurotrophy. Funding Statement: This work was funded by the National Natural Science Foundation of China (Nos. 81671158 and 81771261), and the Natural Science Youth Foundation of China (No. 81701165), and the Natural Science Foundation of Chongqing Science and Technology Committee, China (No. cstc2015jcyjA10048). Declaration of Interests: The authors declare that they have no competing interests. Ethical Approval Statement: All animals used in this experiment were cared for in strict accordance with the Guide for the Care and Use of Laboratory Animals (NIH Publication No. 85-23, revised 1996). All animal experimental procedures were approved by the Ethics Committee of Experimental Animals of Chongqing Medical University.