摘要目的 通过研究高、低吗啡条件性位置偏爱(conditioned place preference,CPP)大鼠海马CA1区突触界面结构参数的变化,为吗啡依赖易感性差异提供形态学依据.方法 将雄性SD大鼠随机分为实验组(130只)和生理盐水对照组(30只).实验组按剂量递增法腹腔注射吗啡建立吗啡依赖模型.分别对2组大鼠进行CPP训练和测评,根据测评值将实验组大鼠再次分为高、中、低偏爱组,中偏爱组淘汰.于末次吗啡注射后3h、戒断后3d和14d将高、低偏爱组和对照组各选取8只大鼠处死,取海马CAI区按照标准程序制成电镜样本,电镜观察摄像,图像分析软件分析测量突触界面结构参数.结果 ①预测试时3组大鼠CPP值之间的差异无显著性(F=0.78,P=0.47);处理因素终止后3h、3d、14d 3组大鼠CPP值差异有极显著性(P<0.01);两两比较显示高偏爱组CPP值高于低偏爱组,差异有极显著性(P<0.01).②在3h和3d时,3组大鼠PSD厚度(突触后致密物质厚度)、突触间隙宽度差异有极显著性(P=0.01～0.03),并且高偏爱组的PSD厚度[(15.20±3.65)nm]小于低偏爱组[(17.63±6.61)nm],差异具有显著性(P<0.05);高偏爱组间隙宽度[(5.77±2.08)nm]大于低偏爱组[(4.92±1.65)nm],差异具有显著性(P<0.05);在14d时,3组大鼠PSD厚度差异有极显著性(P=0.00),并且高偏爱组的PSD厚度[(16.22±4.93)nm]小于低偏爱组[(18.42±3.78)nm],差异具有显著性(P<0.01).结论 高偏爱组大鼠海马CA1区突触间隙宽度的测量值大于低偏爱组,PSD厚度的测量值小于低偏爱组,上述变化可能是吗啡依赖易感性差异的突触界面结构基础.

abstractsObjective To investigate changes of synaptic interface structural in the hippocampus Cal in high and low conditioned place preference(CPP) rats after chronic morphine treatment.Methods The male SD rats were randomly distributed to experiment group 130 cases(intraperitoneal injected morphine twice a day for ten days in an ascending dosage schedule) and control group 30 cases(injected saline of the same volume at same time).The rats in experiment group were re-classified into high preference group(HP),middle group and low preference group(LP) according to the numerical value of the CPP.The middle group was rejected.The rats in HP and LP were scarified at the time of 3h,3d and 14d after the last injection.The hippocampus Cal were removed and prepared for electron microscope specimen.The synaptie interface structure parameter were analyzed by image processing technique.Results ①No significant difference of pretest scores staying at the non-preference chambet existed among the three groups(F=0.78,P=0.47).However,the test scores of the CPP minus the time stayed at pretest natural preference in the high group was significantly higher than that of the low group(P=0.00).②At the 3h and 3d,the PSD of the high group((15.20±-3.65)nm) was significantly lower than low group((17.63±6.61)nm,P<0.01);the synaptic cleft of high group((5.77±2.08)nm) was significantly higher than low group ((4.92±1.65)nm,P<0.05).At the 14d,the PSD of the high group((16.22±4.93)nm) was significantly lower than low group((18.42±3.78)nm,P<0.01).Conclusion In hippocampal Cal area the synaptic cleft in the HP group was higher than that of LP group,the post-synaptic density in the HP group was lower than that of LP group.These changes may be the synaptic basic of the different susceptibility.