血管性痴呆大鼠脑内超微结构变化及生长抑素和nNOS的表达

The ultrastructural changes and the expressions of somatostatin and nNOS in the brain of vascular dementia rats

目的研究血管性痴呆(VD)大鼠生长抑素(SS)、一氧化氮合酶(nNOS)的变化,探讨两者与认知功能的关系。方法将30只14～15w龄大鼠随机分为假手术组(SOG)和模型组(MDG),MDG组采用双侧颈总动脉丝线结扎方法,制备慢性前脑缺血动物模型,SOG组仅分离双侧颈总动脉,但不阻断血流。应用水迷宫实验测试大鼠空间学习记忆能力,应用透射电镜观察大鼠神经元超微结构变化,应用免疫组化方法检测海马及颞叶皮层SS及nNOS的表达情况。结果水迷宫实验中MDG组大鼠的逃避潜伏期(69.70±4.77)s较SOG组(12.93±2.77)s明显延长(P<0.05),MDG组大鼠的跨平台次数(1.80±1.31)较SOG组(8.33±1.30)明显减少(P<0.05)。透射电镜观察,海马神经元高度水肿,核固缩或崩解,线粒体肿胀。免疫组化结果表明,海马区SS的表达MDG组(3.07±1.44)较SOG组(13.73±1.87)明显下降(P<0.05),颞叶皮层区SS的表达MDG组大鼠(2.73±0.96)较SOG组(12.93±1.67)明显下降(P<0.05);海马区nNOS的表达MDG组大鼠(29.60±2.03)较SOG组(9.33±1.63)明显增加(P<0.05),颞叶皮层区nNOS的表达MDG组大鼠(28.87±2.47)较SOG组(8.40±1.64)明显增加(P<0.05)。结论VD大鼠学习记忆能力降低,脑内超微结构变化明显,脑内SS表达水平下降、nNOS表达水平增高。

Objective To study the changes of the somatostatin （ SS）, nitric oxide synthase （nNOS） of thevascular dementia （VD） rats, and to explore the relationship between them and the cognitive function. Methods 30 14 - 15-month-old rats were randomly divided into sham operation （SOG） and model groups （MDG）, MDG group was ligated bilateral carotid artery by thread to prepare for the animal model of the chronic front cerebral ischemia. SOG group was only separated bilateral main carotid artery, but was not blocked the blood flow. Water maze test was used to test the abilities of spatial learning and memory of the rats. The transmission electron microscope was used to observe uhrastructural changes in rat neurons; immunohistochemieal method was adopted to detect the SS and nNOS expressions in hippocampus and temporal cortex. Results In the water maze test, the escape latency of the MDG rats [ （69.70 ± 4.77 ） s ] was significantly longer than that of SOG group [ （ 12. 93 ±2. 77） s, P 〈0.05] ,the number of cross-platform of MDG rats （ 1.80± 1.31 ） was decreased significantly compared with that in SOG group [ （ 8.33 ± 1.30 ）, P 〈 0. 05 ]. TEM observation showed that there was high degree of edema in hippocampal neurons, karyopyknosis or collapse, and mitochondrial swelling. Immunohistochemistry results showed that the expression of SS in hippocampus was decreased significantly in MDG group （3.07 ± 1.44） compared with that in SOG group [ （ 13.73 ±1. 87）, P 〈 0. 05 ], the expression of SS in temporal lobe was decreased significantly in MDG group（2. 73 ±0. 96） compared with that in SOG group [ （ 12. 93 ＋ 1.67）, P 〈0. 05] , the expression of nNOS in hippocampus was increased significantly in MDG group （29. （30 ± 2. 03 ） compared with that in SOG group [ （9. 33 ± 1.63）, P 〈 0. 05 ], the expression of nNOS in temporal lobe was increased significantly in MDG group （ 28. 87± 2. 47 ） compared with that in SOG group [ （8. 40 ± 1.64）, P 〈0. 05~. Conclusions The abilities of learning and memory of VD rats with are reduced, and the ultrastructure in the brain are significantly changed, the level of SS in the brain is decreased, the nNOS expression is increased.