岛叶μ型阿片受体活性水平对吗啡成瘾大鼠学习记忆功能的影响

Effect ofμ-opioid receptor expression on learning and memory in insular cortex of morphine addicted rats

目的探讨岛叶μ型阿片受体(MOR)活性水平对吗啡成瘾大鼠学习记忆功能的影响。方法用吗啡和盐酸纳洛酮构建大鼠成瘾模型,并随机分为模型组、对照组和实验组,每组6只;另取6只正常大鼠注射等量0.9%NaCl作为正常组。正常组与模型组均不给予其他处理,实验组和对照组通过10%水合氯醛麻醉,于前岛叶分别单次注射AAV悬浊液2μL及等量空载体,注射速度为0.25μL·min^-1。用Intellicage大鼠全自动行为学监测系统,在无干扰情况下持续观察大鼠空间位置学习情况。用免疫荧光及Western Blotting检测岛叶MOR及环磷腺苷效应元件结合蛋白(CREB)的表达情况。结果实验组、对照组、模型组和正常组的位置学习阶段正确访问次数分别为(92.1±16.4),(88.4±18.1),(83.6±17.9)和(150.3±29.8)次,位置逆转学习阶段正确访问次数分别为(85.4±17.1),(74.8±15.4),(86.8±20.2)和(140.8±36.7)次,MOR灰度值比分别为0.99±0.12,1.23±0.16,1.19±0.16和0.96±0.12,CREB灰度值比分别为0.73±0.06,0.45±0.04,0.51±0.05和0.83±0.07,正常组的上述指标与实验组、模型组和对照组相比,差异均有统计学意义(均P<0.05)。结论吗啡成瘾可对大鼠学习记忆功能造成损害。岛叶MOR的抑制可以提高吗啡成瘾大鼠CREB的表达含量,但在行为学上无明显差异。

Objective To explore the effect ofμ-opioid receptor(MOR)activity on learning and memory in insular cortex of morphine addicted rats.Methods Morphine and naloxone hydrochloride were used to establish addiction model of rats,which were randomly divided into model group,control group and experimental group with 6 rats in each group.Another 6 normal rats were injected with 0.9%NaCl as the normal group.Apart from the normal group,the experimental group and the control group were anesthetized with 10%chloral hydrate.2μL of adeno-associated virus(AAV)suspension and the same amount of empty carrier were injected into the anterior insula,the injection rate was 0.25μL·min^-1.The spatial learning memory of the rats were observed through intellicage without interference.The expressions of cAMP-response element binding protein(CREB)and MOR were observed through immunofluorescence and Western Blotting.Results In the experimental group,the control group,the model group and the normal group,location learning test showed the numbers of correct visits were(92.1±16.4),(88.4±18.1),(83.6±17.9)and(150.3±29.8);location reversal learning test showed the numbers were(85.4±17.1),(74.8±15.4),(86.8±20.2)and(140.8±36.7);the relative expressions of MOR were 0.99±0.12,1.23±0.16,1.19±0.16 and 0.96±0.12;The relative expressions of CREB were 0.73±0.06,0.45±0.04,0.51±0.05 and0.83±0.07.Compared with the experimental group,the model group and the control group,the differences of the above results in the normal group had statistical significance(all P<0.05).Conclusion Morphine addiction can cause damages to learning-memory functions of rats.For the rat’s insular lobe,the inhibition of MOR can increase the expression of CREB,but there is no obvious difference in behavior.