星状神经节阻滞对老龄大鼠术后海马CA3区突触结构的影响

Effect of stellate ganglion block on postoperative synaptic structure in hippocampal CA3 region in aged rats

目的 评价星状神经节阻滞（SGB）对老龄大鼠术后海马CA3区突触结构的影响.方法 健康老龄雄性SD大鼠72只,20～ 22月龄,体重550～ 650 g,采用随机数字表法,将其分为3组（n=24）：对照组（C组）、手术组（O组）和SGB＋手术组（SGB组）.SGB组于右侧星状神经节处注射0.25％布比卡因0.15 ml行SGB.操作结束15 min时,O组和SGB组进行剖腹探查术,手术时间30 min.于术后1d时,随机取6只大鼠,采用Y型迷宫测试认知功能,记录达标训练次数和达标时间;分别于术后1、3和7d时,随机处死6只大鼠,取海马CA3区组织,电镜下进行观察,测量突触间隙、突触后膜致密物厚度、突触活性区长度和突触界面曲率.结果 与C组比较,O组和SGB组达标时间延长,达标训练次数增加,O组术后1、3和7d时海马CA3区突触间隙增宽,突触后膜致密物厚度变薄,突触活性区长度缩短,突触界面曲率减小（P＜0.05）,SGB组突触结构各指标差异无统计学意义（P＞0.05）;与O组比较,SGB组达标时间缩短,达标训练次数减少,术后1、3和7d时海马CA3区突触间隙减小,突触后膜致密物厚度增厚,突触活性区长度延长,突触界面曲率增大（P＜0.05）.结论 SGB改善老龄大鼠术后认知功能障碍的机制可能与抑制海马CA3区突触结构改变有关.

Objective To evaluate the effect of stellate ganglion block （SGB） on postoperative synaptic structure in hippocampal CA3 region in aged rats.Methods Seventy-two male Sprague-Dawley rats,aged 20-22 months,weighing 550-650 g,were randomly divided into 3 groups （n =24 each） using a random number table：control group （group C）,operation group （group O） and SGB ＋ operation group （group SGB）.Group SGB received right SGB with 0.25% bupivacaine 0.15 ml.Groups O and SGB underwent 30 min of exploratory laparotomy starting from 15 min after the end of administration.Y-maze test was performed on 1 day after operation in 6 rats chosen from each group for assessment of cognitive function.The frequency of standard training and standard time were recorded.Six rats were chosen from each group on 1,3 and 7 days after operation and sacrificed and the hippocampal CA3 region was isolated for microscopic examination and for measurement of synaptic structure.Results Compared with group C,the standard time was significantly prolonged,and the frequency of standard training was increased in groups O and SGB,the width of synaptic cleft was increased,the thickness of post-synaptic density was decreased,the length of active zones was shortened,and the curvature of the synaptic interface was decreased on 1,3 and 7 days after operation in group O （P 〈 0.05）,and no significant changes were found in each synaptic structure parameter in group SGB （P 〉 0.05）.Compared with group O,the standard time was significantly shortened,the frequency of standard training was decreased,the width of synaptic cleft was decreased,the thickness of the post-synaptic density was increased,the length of active zones was prolonged,and the curvature of the synaptic interface was increased on 1,3 and 7 days after operation in group SGB （P 〈 0.05）.Conclusion The mechanism by which SGB improves the postoperative cognitive dysfunction in aged rats may be related to inhibition of changes of synaptic structure in hippocampal CA3 region.