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目的:研究人参皂甙Rg_1对自由活动大鼠突触功能可塑性的影响及作用机制。方法:应用细胞外微电极记录技术,大鼠埋植电极后d6予以Rg_1(10,30mg/kg,ip)12d,记录(直至停药后d3)其齿状回群体峰电位(PS)。大鼠给予Rg_1(10,30mg/kg,ip)12d,据Timm染色法观察海马CA3区苔辞纤维出 芽情况。以免疫组化技术检测齿状回颗粒细胞层GAP-43表达水平。结果:1)Rg_1可显著降低诱发PS的阈值,提高清醒自由活动大鼠的突触传递效能,诱导LTP形成,停药3d后,LTP仍可维持。2)Rg_1组大鼠齿状回颗粒细胞层及齿状回门区GAP-43表达显著增加。3)Timm染色显示海马CA3区苔藓纤维出芽增加。结论:Rg_1可使自由活动大鼠PP-DG突触传递效能发生以LTP为主的可塑性变化,其机制为齿状回颗粒细胞GAP-43表达增加,其投射靶区海马CA3苔藓纤维明显出芽增加,这呈正反馈性增强了突触传递效能。
Objective: To study the effect of ginsenoside Rg_1 on synaptic function plasticity in free-motion rats and its mechanism of action. METHODS: Using extracellular microelectrode recording technique, rats were implanted with d6 and d6 (10, 30 mg/kg, ip) for 12 d after implantation of the electrode. The dentate gyrus population potential (PS) was recorded (d3 until discontinuation). The rats were given Rg_1 (10, 30 mg/kg, ip) for 12 days. The budding condition of mossy fibers in hippocampal CA3 region was observed by Timm staining. The expression of GAP-43 in granule cell layer of dentate gyrus was detected by immunohistochemistry. Results: 1) Rg_1 can significantly reduce the threshold of induced PS, increase the synaptic transmission efficiency of rats with conscious free movement, and induce the formation of LTP. After 3 days withdrawal, LTP can be maintained. 2) The expression of GAP-43 in dentate gyrus granule cell layer and dentate gyrus was significantly increased in Rg-1 rats. 3) Timm staining showed increased sprouting of mossy fibers in hippocampal CA3 area. CONCLUSION: Rg_1 can induce LTP-based plasticity in the synaptic transmission of PP-DG in free-active rats. The mechanism is that the expression of GAP-43 increases in the dentate gyrus granule cells, and the sprouting of the hippocampal CA3 mossy fiber in the projection target area increases. This positive feedback enhances synaptic transmission efficiency.