间歇性禁食对老龄大鼠术后认知功能的影响及JAK2/STAT3信号通路在其中的作用

Effect of intermittent fasting on postoperative cognitive function in aged rats and role of JAK2/STAT3 signaling pathway

目的评价间歇性禁食对老龄大鼠术后认知功能的影响及Janus激酶2(JAK2)/信号转导和转录激活因子3(STAT3)信号通路在其中的作用。方法SPF级健康雄性SD大鼠80只,20月龄,体质量600~650 g,采用随机数字表法分为4组(n=20):对照组(C组)、术后认知功能障碍(POCD)组(P组)、间歇性禁食+POCD组(IF+P组)和间歇性禁食+JAK2/STAT3信号通路激动剂C-A1+POCD组(IF+A+P组)。IF+P组和IF+A+P组接受为期4周的间歇性禁食:禁食24 h而后自由进食24 h,全程不限制水的摄入;IF+A+P组大鼠于间歇性禁食期间每天腹腔注射C-A1100μg/kg。P组、IF+P组和IF+A+P组大鼠在七氟烷麻醉下行剖腹探查术制备POCD模型。术后3 d时行旷场实验评估大鼠自主运动功能,术后3~7 d时行Morris水迷宫实验评估大鼠认知功能。水迷宫实验结束后处死大鼠取海马CA1区,采用Western blot法测定JAK2、磷酸化JAK2(p-JAK2)、STAT3、磷酸化STAT3(p-STAT3)的表达,采用ELISA法检测IL-6、IL-1β和TNF-α的含量,HE染色观察海马CA1区病理学结果。结果4组旷场实验运动速度、路程以及旷场中心停留时间比较差异无统计学意义(P>0.05)。与C组比较,P组逃避潜伏期延长,穿越原平台位置次数减少,海马CA1区p-JAK2/JAK2比值和p-STAT3/STAT3比值、IL-6、IL-1β和TNF-α含量升高(P<0.05),海马CA1区出现病理学损伤。与P组比较,IF+P组逃避潜伏期缩短,穿越原平台位置次数增加,海马CA1区p-JAK2/JAK2比值和p-STAT3/STAT3比值、IL-6、IL-1β和TNF-α含量降低(P<0.05),海马CA1区病理学损伤减轻。与IF+P组比较,IF+A+P组逃避潜伏期延长,穿越原平台位置次数减少,海马CA1区p-JAK2/JAK2比值和p-STAT3/STAT3比值、IL-6、IL-1β和TNF-α含量升高(P<0.05),海马CA1区病理学损伤加重。结论间歇性禁食可改善老龄大鼠术后认知功能,其机制可能与抑制JAK2/STAT3信号通路激活,减轻海马CA1区神经炎症反应有关。

Objective To evaluate the effect of intermittent fasting on postoperative cognitive function in aged rats and the role of Janus kinase 2/signal transducer and activator of transcription 3(JAK2/STAT3)signaling pathway in it.Methods Eighty SPF healthy male Sprague-Dawley rats,aged 20 months,weighing 600-650 g,were divided into 4 groups(n=20 each)using a random number table method:control group(group C),postoperative cognitive dysfuction(POCD)group(group P),intermittent fasting+POCD group(group IF+P),and intermittent fasting+JAK2/STAT3 signaling pathway agonist C-A1+POCD group(group IF+A+P).IF+P group and IF+A+P group underwent a 4-week intermittent fasting procedure:fasting for 24 h followed by free eating for 24 h,without limiting water intake throughout the entire process,in addition C-A1100μg/kg was intraperitoneally injected daily during intermittent fasting in IF+A+P group.Rats underwent exploratory laparotomy under sevoflurane anesthesia to prepare POCD models in P group,IF+P group and IF+A+P group.Three days after surgery,open field tests were conducted to evaluate the autonomous motor function of rats,and Morris water maze tests were conducted to evaluate the cognitive function of rats on 3-7 days after surgery.After the Morris water maze tests,the rats were sacrificed and the hippocampal CA1 area was removed for determination of the expression of JAK2,phosphorylated JAK2(p-JAK2),STAT3,and phosphorylated STAT3(p-STAT3)(by Western blot)and contents of interleukin-6(IL-6),IL-1βand tumor necrosis factor-alpha(TNF-α)(by enzyme-linked immunosorbent assay)and for microscopic examination of pathological changes of hippocampal CA1 region(using HE staining).Results There was no statistically significant difference in the speed,distance and duration of stay at the center of the open field test among the four groups(P>0.05).Compared with group C,the escape latency was significantly prolonged,the number of crossing the original platform was reduced,and the p-JAK2/JAK2 ratio,p-STAT3/STAT3 ratio and contents of IL-6,IL-1βand TNF-αin the hippocampal CA1 region were increased(P<0.05),and the pathological damage occurred in the hippocampal CA1 region in group P.Compared with P group,the escape latency was significantly shortened,the number of crossing the original platform was increased,and the p-JAK2/JAK2 ratio,p-STAT3/STAT3 ratio and contents of IL-6,IL-1βand TNF-αin the hippocampal CA1 region were decreased(P<0.05),and the pathological damage in the hippocampal CA1 area was significantly alleviated in IF+P group.Compared with IF+P group,the escape latency was significantly prolonged,the number of crossing the original platform was reduced,and the p-JAK2/JAK2 ratio,p-STAT3/STAT3 ratio and contents of IL-6,IL-1βand TNF-αin the hippocampal CA1 region were increased(P<0.05),and the pathological damage in the hippocampal CA1 area was aggravated in group IF+A+P.Conclusions Intermittent fasting can improve postoperative cognitive function in aged rats,and the mechanism may be related to inhibiting the JAK2/STAT3 signaling pathway and reducing the neuroinflammatory responses in the hippocampal CA1 region.