应激对大鼠海马Glu-NMDA受体通路的影响及锌的保护机制

目的：探讨光-电应激对不同锌水平大鼠海马突触体谷氨酸摄取能力及海马N-甲基-D-门冬氨酸(NMDA)受体容量和亲和力的影响。方法：通过光-电刺激建立大鼠应激模型。观察实验动物旷场行为变化。以^3H-L-Glu作为放射配体进行海马NMDA受体结合反应,以放免法测定海马突触体谷氨酸摄取能力。结果：缺锌动物在旷场中活动较少,海马NMDA受体容量减少、海马突触体谷氨酸摄取能力显著下降;与相应非应激组比较,各应激组动物在旷场中停留时间延长,水平和垂直运动呈现减少趋势、海马NMDA受体容量均有增加趋势而海马突触体谷氨酸摄取能力有下降趋势,但以上各项指标仅缺锌应激组出现统计学差异。结论：光-电应激可导致大鼠在旷场中的行为异常,在缺锌情况下,实验动物出现更严重的异常反应。表明,海马NMDA受体容量及突触体谷氨酸摄取能力的变化参与了应激反应过程,推测其机制与海马Glu-NMDA受体通路的改变有关。

Effects of stress on hippocampal Glu-NMDAR pathway in rats and mechanism of zinc protection

Aim: To observe the effects of stress on Glu uptake and NMDAR of hippocampus synaptosome in rats with different zinc status. Methods: Stress model was established by photoelectric stimulus. The behaviors of rats were tested in open-field case. 3 H -L-Glu was taken as radioligand to detect the NMDAR binding.Glu uptake was determined with radioimmunoassay. Results: Compared with CT rats, ZD rats performed less movement in open-field test, both Bmax of NMDAR and 3 H -L-Glu uptake of hippocampus in these rats were significantly decreased.Compared with corresponding non-stressed groups, the stressed groups appeared longer latency and less movement in open-field test.Increased Bmax of NMDAR and decreased 3 H -L-Glu uptake were observed in all stressed rats,but only in SZD rats these indices showed statistical difference. Conclusion: Abnormal behaviors of rats induced by photoelectric stress were observed in open-field test, which was more serious in zinc deficiency rats.It is supposed that the Glu-NMDAR pathway is involved in the process of stress reaction.As it shows in our experiment,the changes of Bmax of NMDAR and 3 H -L-Glu uptake of hippocampus synaptosome seems to be a part of the mechanisms of stress action.