神经胶质源性神经营养因子经鼻给药对老龄大鼠术后认知功能障碍的影响

Effects of intranasal administration of glial cell line-derived neurotrophic factor on postoperative cognitive dysfunction in aged rats

目的评价神经胶质源性神经营养因子(GDNF)经鼻给药对老龄大鼠术后认知功能障碍的影响。方法健康老龄SD大鼠40只,雌雄不拘,21~23月龄,体重480~600 g,采用随机数字表法将其分为4组(n=10):假手术组(S组)、外科手术组(O组)、低剂量GDNF经鼻给药组(G1组)和高剂量GDNF经鼻给药组(G2组)。O组、G1组和G2组于水合氯醛麻醉下行剖腹探查手术,S组仅行假手术。外科手术或假手术后连续3 d,G1组和G2组分别每天经鼻吸入GDNF 25和50 μg(溶于PBS 25 μl),S组和O组分别每天经鼻吸入PBS 25 μl。术后第3~7天行Morris水迷宫实验;实验结束后处死大鼠,取海马组织,采用Western blot法检测GDNF、高迁移率组蛋白B1(HMGB1)、IL-1β、TNF-α、活化的caspase-3和Bax的表达水平。结果与S组比较,O组术后第5~7天逃避潜伏期延长,穿越平台次数减少,目标象限停留时间缩短,海马GDNF表达下调,IL-1β、TNF-α、HMGB1、活化的caspase-3和Bax表达上调,G1组和G2组穿越平台次数减少,目标象限停留时间缩短,海马IL-1β和TNF-α表达上调(P<0.05);与O组比较,G1组和G2组术后第5~7天逃避潜伏期缩短,穿越平台次数增加,目标象限停留时间延长,海马GDNF表达上调,TNF-α、HMGB1、活化的caspase-3和Bax表达下调,G1组海马IL-1β表达下调(P<0.05);与G1组比较,G2组海马TNF-α表达下调(P<0.05),其余指标差异无统计学意义(P>0.05)。结论 GDNF经鼻给药可改善老龄大鼠术后认知功能障碍,其机制可能与抑制神经炎症反应和神经细胞凋亡有关。

Objective To evaluate the effects of intranasal administration of glial cell line-derived neurotrophic factor(GDNF)on postoperative cognitive dysfunction in aged rats.Methods Forty healthy Sprague-Dawley rats of both sexes,aged 21-23 months,weighing 480-600 g,were divided into 4 groups(n=10 each)using a random number table method:sham operation group(group S),operation group(group O),intranasal administration of low-dose GDNF group(group G1)and intranasal administration of high-dose GDNF group(group G2).Rats underwent exploratory laparotomy under anesthesia with chloral hydrate in O,G1 and G2 groups,while the rats in group S only received sham operation.The rats in group G1 and group G2 were intranasally treated with GDNF 25 and 50μg(in 25μl of PBS),respectively,and PBS 25μl was nasally administered in group S and group O every day for 3 consecutive days after operation or sham operation.Morris water maze test was performed on days 3-7 after surgery,and then the rats were sacrificed,and hippocampal tissues were removed for determination of the expression of GDNF,high mobility group box 1(HMGB1),interleukin-1β(IL-1β),tumor necrosis factor-α(TNF-α),activated caspase-3 and Bax(by Western blot).Results Compared with group S,the escape latency was significantly prolonged on days 5-7 after operation,the number of crossing the platform was reduced,time spent in the target quadrant was shortened,expression of GDNF was down-regulated,and expression of IL-1β,TNF-α,HMGB1,activated caspase-3 and Bax in hippocampi was up-regulated in group O,and the number of crossing the platform was reduced,time spent in the target quadrant was shortened,and expression of IL-1βand TNF-αwas up-regulated in G1 and G2 groups(P<0.05).Compared with group O,the escape latency was significantly shortened on days 5-7 after operation,the number of crossing the platform was increased,time spent in the target quadrant was prolonged,expression of GDNF was up-regulated,expression of TNF-α,HMGB1,activated caspase-3 and Bax in hippocampi was down-regulated in G1 and G2 groups,and IL-1βin hippocampi was down-regulated in group G1(P<0.05).Compared with group G1,the expression of TNF-αin hippocampi was down-regulated(P<0.05),and no significant change was found in the other parameters mentioned above in group G2(P>0.05).Conclusions Intranasal administration of GDNF can improve postoperative cognitive dysfunction,and the mechanism may be related to inhibiting neuroinflammatory responses and neuroapoptosis in aged rats.