Ro20-1724对多次氯胺酮麻醉幼年大鼠成年后学习记忆功能的影响

Effects of Ro20-1724 on long term memory after repeated injection of ketamine in immature rats

目的探讨磷酸二酯酶-4抑制剂Ro20-1724对多次氯胺酮麻醉幼年大鼠成年后学习记忆功能的影响及可能机制。方法筛选合格的21日龄的SD大鼠60只,雌雄不拘。随机分为五组(n=12):空白对照组(A组)、生理盐水组(予以等容量生理盐水,B组)、氯胺酮组(腹腔注射70mg/kg氯胺酮,C组)、氯胺酮+Ro20-1724组(腹腔注射70mg/kg氯胺酮,30min后给予0.5mg/kg R020-1724,D组)、氯胺酮+Ro20-1724溶媒组(腹腔注射70 mg/kg氯胺酮,30 min后给予等量R020-1724的溶媒无水乙醇,E组),每天1次,连续7d。出生8周后利用Morris水迷宫进行定位航行试验和空间搜索试验,获取多次氯胺酮麻醉的幼年大鼠成年后对水迷宫的学习和记忆获取能力以及平台空间位置的记忆保持能力。同时用蛋白质印迹法检测成年后大鼠海马磷酸化环腺苷酸应答元件结合蛋白(Phosphorylated cAMP response element binding protein,p-CREB)的表达以及电子显微镜观察成年后大鼠海马神经元超微结构。结果 C组和E组逃避潜伏期明显长于A组和B组(P<0.05),穿越平台次数明显少于A组和B组(P<0.05),海马p-CREB表达明显少于A组和B组(P<0.05);C组和E组逃避潜伏期明显长于D组(P<0.05),穿越平台次数明显少于D组(P<0.05),海马p-CREB表达明显少于D组(P<0.05);而A组与B组、C组与E组差异无统计学意义。电子显微镜显示C组和E组海马神经元肿胀较明显和普遍,有核膜不完整,核糖体密度低,粗面内质网有脱颗粒现象。D组海马神经元稍肿胀,线粒体密度稍低,核膜基本完整。结论磷酸二酯酶-4抑制剂Ro20-1724(0.5mg/kg)可减轻多次氯胺酮(70mg/kg)麻醉幼年大鼠引起的成年后学习记忆的受损,其机制可能与磷酸二酯酶-4抑制剂Ro20-1724(0.5mg/kg)增强了海马中cAMP/CREB信号传导以及减轻了海马神经元的损伤有关。

Objective Experiments were performed to investigate the possible mechanism of the PDE-4 inhibitor R020-1724 on long term memory of immature rats after repeated ketamine use. Methods Sixty 21 days aged SD rats were randomly allocated into 5 groups （n=12） . A：Blank control group;B.. Saline control groups C： Ketamine D.. Ketamine＋Ro20-1724; E： Ketamine＋ Vehicle, Ro20-1724（0. 5 mg/kg） or its vehicle（Ethanol）was administered intraperitoneally 30 minutes after giving Ketamine （70 mg/kg）once daily for 7 days. 8 weeks after birth, The Morris water maze was used to test the ability of learning and spatial localization of rats. At the end of the experiment, the hippocampus was removed for Western blot and electron microscopic examination.Results In Morris water maze test, compared with group A and B, the escape latency in group C and E was significantly longer （P〈0. 05）, the ability of spatial localization was lower （P〈0. 05）, and the expression of pCREB in the hippocampus was also decreased（P〈0. 05）.Compared with group D, the escape latency in group C and E was significantly longer （P〈0. 05）, the ability of spatial localization was lower （P 〈0. 05）, and the expression of p-CREB in the hippocampus was also decreased（P〈0.05）, while there was no significant difference between group A and B,group C and E. Electron microscopy showed that hippocampal neurons was swelling obviously, the nuclear was in complete, density of the ribosome was low, the rough endoplasmic reticulum has degranulation in group C and E. These can be relieved by Ro20-1724 （0. 5 mg/kg）.Conelusion These results suggest that the PDE-4 inhibitor Ro20-1724 （0. 5 mg/kg） reverses cognitive deficits associated with repeated ketamine use most likely via increasing cAMP/CREB signaling in the hippocampus and relieved hippocampal neuron injuries.