丙泊酚通过抑制突触tPA释放致发育期小鼠海马神经元毒性损伤的机制研究

Neonatal exposure to propofol leads to neurobehavioral abnormalities during adolescence and adulthood, which is related to the neurotoxicity of propofol in developing neurons. Our preliminary studies demonstrated that propofol-induced neurotoxicity in hippocampal neurons of developing mice can be reversed by p75NTR blockade, but the underlying mechanism is unclear. We speculate that propofol-induced neurotoxicity in developing neurons is mediated by reduced synaptic tPA release and enhanced effect of proBDNF-p75NTR signaling pathway，which inhibit the Tiam1 activation mediated Rac1 activation and RhoA inhibition, and finially induce neurotoxicity and the hippocampal function-related long-term neurocognitive deficits.We plan to apply immunofluorescence microscopy, molecular biology techniques and Morris water maze, to investigate the mechanism of propofol-induced neurotoxicity in hippocampal neurons of developing mice via inhibition of synaptic tPA release, to select the potential molecular target for the prevention of long-term spatial learning/memory induced by propofol neurotoxicity. The results from our study may serve as potential therapeutic approaches and mechanistic framework for the prevention of propofol -induced neurotoxicity.

发育期个体暴露于麻醉药丙泊酚会在青春期或成年后出现神经行为异常，这与丙泊酚对发育期神经元的毒性损伤作用相关。申请人前期研究发现，阻断发育期小鼠海马神经元p75NTR可逆转丙泊酚的神经毒性作用，但机制不详。我们推测丙泊酚可能是通过减少海马神经元突触tPA释放，进而减少纤溶酶生成，造成proBDNF向mBDNF转化减少，导致proBDNF-p75NTR信号通路占优势，从而抑制突触内Tiam1激活所介导的Rac1激活和RhoA抑制，最终导致神经元毒性损伤及与该区域功能相关的远期学习记忆能力损害。本研究拟采用免疫荧光电镜、Morris水迷宫及分子生物学技术，在神经元、脑片和整体动物水平探讨“丙泊酚通过抑制突触tPA释放致发育期小鼠海马神经元毒性损伤的分子机制”，鉴定防治丙泊酚神经毒性所致远期空间学习记忆能力损害的可能干预靶点，为临床预防和治疗丙泊酚神经毒性提供实验和理论依据。

发育期个体暴露于麻醉药丙泊酚会在青春期或成年后出现神经行为异常，这与丙泊酚对发育期 神经元的毒性损伤作用相关。申请人通过本课题研究发现，阻断发育期小鼠海马神经元p75NTR可逆转丙泊酚的神经毒性作用，我们推测丙泊酚可能是通过减少海马神经元突触tPA释 放，进而减少纤溶酶生成，造成proBDNF向mBDNF转化减少，导致proBDNF-p75NTR信号通路占优 势，从而抑制突触内Tiam1激活所介导的Rac1激活和RhoA抑制，最终导致神经元毒性损伤及与 该区域功能相关的远期学习记忆能力损害。本课题最主要的发现为：1）丙泊酚可通过抑制神经元释放 tPA 而对体外培养的新生小鼠发育期海马神 经元产生毒性损伤作用 ，外源性加入 tPA 可部分逆转丙泊酚的神经毒性作用，此外，我们又发现2）Pink1介导的信号通路可能也是丙泊酚对发育期神经元毒性损伤的另一个可能的靶点。本研究的主要结果以及今后深入研究的结果能够为临床预防和治疗丙泊酚神经毒性提供实验和理论依据。