短期丰富生存环境对中老年大鼠海马结构及其内有髓神经纤维影响的研究

发布时间：2018-06-21 03:47

本文选题：有髓神经纤维 + 海马结构　；参考：《重庆医科大学》2010年硕士论文

【摘要】： 海马结构在学习和记忆中起着重要作用。衰老引起的海马结构功能的退化最初认为与海马神经元的死亡有关。但是,已有研究表明衰老并不会引起海马结构内显著的神经元死亡。由此推断,空间记忆能力的减退可能与神经纤维的退化有关。大量的研究表明,丰富生存环境可以提高动物的空间记忆能力、增加树突分支、促进胶质细胞生成、促进海马齿状回新生神经元形成和增加神经营养因子mRNA表达等。动物的空间记忆能力在中老年时期开始下降,因此,在此阶段采取行为学手段的干预可能有助于预防或延缓记忆能力的下降。丰富生存环境干预是所有行为学干预手段中最简单易行的,那么丰富生存环境干预对于中老年时期空间记忆能力降低是否有帮助,同时丰富生存环境干预对中老年海马结构有髓神经纤维是否有影响,国内外尚未见报道。本研究旨在探讨丰富生存环境对中老年雌、雄性大鼠空间记忆能力、海马结构及其内有髓神经纤维的影响。本实验首先运用Morris水迷宫探讨丰富生存环境干预对中老年雌、雄性大鼠行为学的作用,然后运用透射电子显微镜和体视学方法定量研究丰富生存环境下中老年雌、雄性SD大鼠海马结构总体积、海马内有髓神经纤维总长度、总体积和平均直径的改变。 1材料与方法 1.1清洁级14个月Sprague-Dawley雌性大鼠22只。随机分为丰富生存环境组12只和标准环境组10只。清洁级14个月Sprague-Dawley雄性大鼠22只。随机分为丰富生存环境组12只和标准环境组10只。丰富生存环境干预后,随机抽取丰富生存环境组雌、雄各5只和标准环境组雌、雄各5只进行后续行为学测试以及形态学分析。 1.2丰富生存环境组(enriched environment group, EE组)大鼠饲养于大箱子中(120 cm×60 cm×50 cm)饲养, 12只/箱,室温21±2℃,12 h光照与12 h黑夜交替,给予足够的食物和水。箱内设有各式各样的物体,每周更换保持新奇感。短期干预时间为4个月。将标准环境组(standard environment group,SE组)大鼠在普通标准箱中(40 cm×30 cm×30 cm)饲养,5只/箱,给予足够的食物和水。箱内不设任何物体。饲养时间为4个月。 1.3干预结束后,用Morris水迷宫进行连续5天的空间记忆能力的测试。前四天为隐藏平台实验,第五天为可见平台实验。记录动物的寻台时间(从入水到找到平台且四肢爬上平台的时间,即潜伏期)。 1.4每只大鼠随机抽取一侧大脑半球,再从海马结构中随机抽取4~6个组织块做成超薄切片,在透射电镜下每张切片上随机抽取15个视野放大9000倍拍照,每只动物拍得75张电镜照片。 1.5运用体视学方法分别计算出中老年雌、雄组大鼠大脑海马结构总体积、海马结构内有髓神经纤维长度密度和总长度、体积密度和总体积以及有髓神经纤维的平均直径。 2结果 2.1在隐藏平台实验中,18月龄SD雌性大鼠的EE组的潜伏期比SE组显著缩短(P0.05),雄性大鼠的EE组与SE组的潜伏期之间不存在显著性差异(P0.05)。在可见平台试验中,18月龄雌、雄性大鼠EE组与SE组的潜伏期均没有显著性差异(P0.05)。 2.2雌性EE组海马结构总体积比SE组增加了11.7%,但两组之间不存在显著性差异(P0.05)。雄性EE组海马结构总体积比SE组增加了4.6%,两组之间也无显著性差异(P0.05)。 2.3雌性EE组海马结构内有髓神经纤维总长度比SE组显著增加了47.4% (P0.01)。雄性EE组海马结构内有髓神经纤维总长度比SE组显著增加了71.8% (P0.05)。雌性EE组海马结构内有髓神经纤维总体积比SE组显著增加了43.4% (P0.01)。雄性EE组海马结构内有髓神经纤维总体积比SE组显著增加了102.9% (P0.05)。雌性EE组海马结构内有髓神经纤维的平均直径比SE组减少了5.2%,但两组之间不存在显著性差异(P0.05)。雄性EE组海马结构内有髓神经纤维的平均直径比SE组增加了33.1%,且差异具有显著性(P0.01)。雌、雄性EE组和SE组大鼠海马结构内有髓神经纤维直径分布图表明雌、雄性EE组大鼠有髓神经纤维总长度的显著性增加主要是由于细小直径的有髓神经纤维增加所致。全文结论 1.本实验首次利用透射电子显微镜和体视学方法定量研究丰富生存环境下中老年雌、雄性SD大鼠海马结构总体积、海马内有髓神经纤维总长度、总体积和平均直径的改变,并同时利用Morris水迷宫进一步探讨了短期丰富生存环境下雌、雄性中老年大鼠的行为学改变。 2.本研究发现短期丰富生存环境可明显提高中老年雌性大鼠的空间记忆能力,但不能提高中老年雄性大鼠的空间记忆能力。这一结果为将来寻找延缓大脑衰老进程的行为学手段提供了重要的理论依据。 3.本研究首次发现短期丰富生存环境能增加中老年雌、雄性大鼠大脑海马结构内有髓神经纤维总长度、总体积,增加中老年雄性大鼠大脑海马结构内有髓神经纤维的平均直径。雌、雄性丰富生存环境组大鼠海马结构内有髓神经纤维总长度的显著性增加主要是由于细小直径的有髓神经纤维增多所致,这一研究结果为进一步认识丰富生存环境改善大脑功能的机制提供了重要的形态学基础。
[Abstract]:Hippocampal structure plays an important role in learning and memory. Degeneration of hippocampal structure caused by aging is originally thought to be associated with the death of hippocampal neurons. However, it has been suggested that aging does not cause significant neuronal death in the hippocampus. Thus, the deterioration of spatial memory ability may be associated with the degeneration of nerve fibers. A large number of studies have shown that rich living environment can improve the spatial memory ability of animals, increase the branches of the dendrites, promote the formation of glial cells, promote the formation of hippocampal dentate gyrus, and increase the expression of neurotrophic factor mRNA. The spatial memory ability of the animals began to decline during the middle and old years. Therefore, this stage is taken. Intervention for learning methods may help prevent or delay the decline in memory ability. Rich living environment intervention is the simplest of all behavioral interventions. The purpose of this study was to explore the effect of rich living environment on spatial memory, hippocampal structure and intramedullary nerve fibers in male and female rats. First, the Morris water maze was used to explore the behavior of male and middle aged female and male rats. Then, study the quantitative research methods of enriched environment in aged female by transmission electron microscopy and stereology, male SD rat hippocampus hippocampus volume, the total length of the myelinated fibers, the total volume and the average diameter of the change.
1 materials and methods
1.1 14 month Sprague-Dawley female rats of 14 month cleaning grade were randomly divided into rich living environment group 12 and standard environment group 10. 22 male rats of clean grade 14 months were randomly divided into rich living environment group 12 and standard environment group 10. The rich living environment after the prognosis, random extraction of the survival environment group of female, 5 male, 5 Only 5 females and the standard environment group were followed up for behavioral tests and morphological analysis.
1.2 (enriched environment group, EE) rats were raised in large boxes (120 cm * 60 cm x 50 cm), 12 / box, room temperature 21 + 2 C, 12 h light and 12 h night alternately, giving enough food and water. There were a variety of objects in the box to keep the novelty a week. The short-term intervention time was 4 months. The standard was 4 months. The standard was 4 months. The environmental group (standard environment group, SE group) rats in the normal standard box (40 cm * 30 cm * 30 cm) feeding, 5 / box, give enough food and water. The box without any objects. The feeding time is 4 months.
1.3 after intervention, for 5 consecutive days of spatial memory by Morris water maze test. The first four days for the hidden platform experiment, fifth days for the visible platform experiment. Animal records search time (from entering the water to find the platform and limbs climbed up to the platform in time, latent period).
Every 1.4 rats were randomly selected from one side of the brain hemisphere, in the hippocampus of 4~6 randomly selected tissue blocks into ultrathin sections under transmission electron microscope in each section on 15 randomly selected view 9000 times magnification pictures, each animal took 75 photos.
1.5 using stereological methods were calculated in elderly female male group, the total volume of the structure of hippocampus in rat hippocampus, myelinated fiber length density and total length, volume density and total volume and mean diameter of the myelinated nerve fibers.
2 Results
2.1 in the hidden platform experiment, the incubation period of the EE group in the 18 month old SD female rats was significantly shorter than that in the SE group (P0.05). There was no significant difference between the EE group and the SE group in the male rats (P0.05). In the visible platform test, there was no significant difference in the latency between the EE group and the SE group of the male rats (P0.05).
2.2 female EE group hippocampus total volume increased by 11.7% compared with SE group, but there was no significant difference between the two groups (P0.05). The total volume of the hippocampal formation of male EE was 4.6% higher than SE group, between the two groups had no significant difference (P0.05).
2.3 the total length of myelinated nerve fibers in the hippocampal structure in the female EE group was significantly increased by 47.4% (P0.01). The total medullary nerve fiber length in the hippocampal structure in the male EE group was 71.8% (P0.05) significantly higher than that in the SE group. The total medullary nerve fiber volume in the hippocampal structure in the female EE group increased by 43.4% (P0.01) in the hippocampus structure of the female EE group. In the hippocampus of the male EE group, the hippocampus structure was in the male EE group. The total volume of myelinated nerve fibers increased by 102.9% (P0.05) significantly than that in the SE group. The average diameter of the myelinated nerve fibers in the hippocampal structure in the female EE group was 5.2% less than that in the SE group, but there was no significant difference between the two groups (P0.05). The average diameter of the myelinated nerve fibers in the hippocampal structure of the male EE group was 33.1% higher than that in the SE group, and the difference was significant. (P0.01). Female and male EE group and SE group rats hippocampus with diameter distribution chart shows that female myelinated nerve fibers, male EE rats had a significant increase in the total length of the myelinated fibers with small diameter is mainly due to the increase of the myelinated fibers.
Full text conclusion
1. the experiment was for the first time to use transmission electron microscope and stereological method to quantitatively study the total volume of the hippocampus structure, the total length, the total volume and the average diameter of the medullary nerve fibers in the hippocampus of the male SD rats in the rich living environment, and further explore the female and male in the short term rich living environment by using the Morris water maze. Behavioural changes in old and middle aged rats.
2. the study found that the short-term rich living environment can obviously improve the spatial memory ability of the middle-aged and old female rats, but can not improve the spatial memory ability of the middle aged and old male rats. This result provides an important theoretical basis for the future search for the behavioral means to delay the aging process of the brain.
3. for the first time, we found that a short term rich environment can increase the average diameter of the medullary nerve fibers in the hippocampus of the male rats. The average diameter of the medullary nerve fibers in the hippocampus of the male rats is increased. Significant increase in the degree of the mean diameter of the myelinated nerve fibers increased due to the results of this study provide important morphological basis for further understanding of the enriched environment to improve brain function mechanism.
【学位授予单位】：重庆医科大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：R329.45

【引证文献】