下丘脑弓状核GABA能神经元调控Schlemm's管开合状态的机制研究

The studies of central nervous system in primary open angle glaucoma (POAG) have suggested that multiple brain nuclei may participate in the pathogenesis of POAG. But the nerve connections of different nuclei and the regulatory mechanism of upstream nuclei to peripheral target site are still unclear. The applicant’s previous studies found that Schlemm’s canal might has an autonomic regulation function and peripheral nerves with vasoactive intestinal peptide (VIP) positive staining anatomically spread around Schlemm’s canal. Besides, in the chronic intraocular pressure hypertension model, the expression of the GABA receptors in arcuate nucleus (ARC) was increased, accompanied with the collapsed Schlemm’s canal. Neuroanatomy has proved that the GABAergic neurons in ARC inhibit the neuron activity of paraventricular nucleus (PVN) and its downstream projections (including the upper sputum nucleus (SSN) to the pterygopalatine ganglion (PPG)). Thus we speculate that the the GABAergic neurons in ARC involve in the regulation of the open-closed state of Schlemm’s canal via ARC→PVN→SSN→PPG→Schlemm’s canal neural circuit. This project intends to prove the neural circuit from ARC to Schlemm's canal by nerve tracing method and clarify the regulatory mechanism of GABAergic neurons in ARC on the open-closed state of Schlemm's canal by optogenetic technique. The results may provide a new theoretical basis for the theory of changes in central nervous system leading to POAG.

原发性开角型青光眼（POAG）的中枢研究提示多个神经核团可能参与POAG的发病过程，但核团之间的联系且对下游靶点部位的调控机制尚不清楚。申请人前期研究发现Schlemm’s管存在自主调节现象及局部血管活性肠肽（VIP）染色阳性的神经纤维；慢性高眼压大鼠模型下丘脑弓状核（ARC）GABA受体表达增加，伴随Schlemm’s管塌陷。神经解剖学已知弓状核GABA能神经元抑制室旁核（PVN）及其下游投射（包括上泌涎核（SSN）至翼腭神经节（PPG））；因此我们推测，弓状核GABA能神经元通过ARC→PVN→SSN→PPG→Schlemm’s管投射环路参与调控Schlemm’s管的开合状态。本项目拟通过神经示踪证明弓状核至Schlemm’s管投射环路；利用光遗传学技术，明确弓状核GABA能神经元对Schlemm’s管开合状态的调控机制，为POAG发病“中枢学说”提供新的理论依据。

原发性开角型青光眼（POAG）的中枢研究提示弓状核（ARC）可能参与POAG的发病过程，但其与其他核团之间的联系且对下游靶点部位的调控机制尚不清楚。既往研究发现Schlemm’s管存在自主调节现象及局部血管活性肠肽（VIP）染色阳性的神经纤维，但该神经纤维来源于上游何处的投射，局部VIP分泌对Schlemm’s管开合状态有何影响？本项目拟通过神经示踪证明弓状核至Schlemm’s管投射环路；利用脑定位注射技术，明确弓状核GABA能神经元对Schlemm’s管开合状态的调控机制。我们发现翼腭神经节（PPG）节后神经通过分泌VIP增加Schlemm’s管内皮细胞LRRK2蛋白表达，保持Schlemm’s管开合状态，从而降低眼压。除此之外，我们还证明弓状核→室旁核（PVH）→上泌涎核（SSN）→翼腭神经节→Schlemm’s管神经投射环路。弓状核GABA能神经元异常兴奋，抑制室旁核→上泌延核→翼腭神经节神经投射，引起Schlemm’s管局部VIP分泌减少，Schlemm’s管管腔塌陷，眼压升高。当我们抑制慢性高眼压大鼠模型弓状核GABA能神经元，将兴奋室旁核→上泌延核→翼腭神经节神经投射，引起Schlemm’s管局部VIP分泌增加，逆转眼压升高。弓状核GABA能神经元通过ARC→PVN→SSN→PPG→Schlemm’s管投射环路，影响Schlemm’s管局部VIP分泌，参与调控Schlemm’s管的开合状态及眼压。这些结果为“原发性开角型青光眼发病中枢机制”学说提供新的理论依据，弓状核及其下游投射环路、VIP-LRRK2通路可能为青光眼治疗提供潜在的药物靶点。