快速老化痴呆小鼠智力、听功能、以及耳蜗螺旋神经节细胞MeCP2的增龄性变化

发布时间：2018-06-22 15:40

本文选题：快速老化小鼠 + 痴呆　；参考：《桂林医学院》2011年硕士论文

【摘要】：目的:本实验旨在探讨快速老化痴呆小鼠(Senescence accelerated dementia mouse/prone,SAMP8)的听功能、智力及耳蜗(Cochlea)组织中MeCP2表达的增龄性变化特点。方法:选用5、7月龄的SAMP8小鼠作为实验组,同龄的抗快速老化小鼠亚系1 ( Senescence accelerated mouse/resistance 1,SAMR1)作为对照组。分别对各组小鼠采用Y型电迷宫及8kHz短纯音听性脑干反应(auditory brainstem response,ABR)检测其智力、双耳听功能(ABR阈值)、耳蜗基底膜铺片硝酸银染色毛细胞计数计算左侧耳蜗底回外毛细胞平均缺失率、应用免疫组织化学染色技术检测不同月龄组小鼠右侧耳蜗中组织中MeCP2蛋白的表达与分布情况。结果: 1、智力检测:实验组5月龄SAMP8小鼠第一天的学习成绩(达标次数、错误次数、全天总反应时间)分别为:8.57±5.97(次)、3.43±1.13(次)、48.47±15.82(s);实验组5月龄SAMP8小鼠第二天的记忆成绩(达标次数、错误次数、全天总反应时间)分别为:5.14±3.33(次)、2.71±0.76(次)、46.19±11.63(s)。实验组7月龄SAMP8小鼠第一天的学习成绩(达标次数、错误次数、全天总反应时间)分别为:15.3±6.58(次)、5.20±1.03(次)、73.09±22.56(s);实验组7月龄SAMP8小鼠第二天的记忆成绩(达标次数、错误次数、全天总反应时间)分别为:11.2±2.39(次)、3.60±0.84(次)、60.05±12.85(s)。对照组5月龄SAMR1小鼠第一天的学习成绩(达标次数、错误次数、全天总反应时间)分别为:7.29±2.29(次)、1.57±0.53(次)、46.87±11.44(s)。对照组5月龄SAMR1小鼠第二天的记忆成绩(达标次数、错误次数、全天总反应时间)分别为:3.57±1.51(次)、0.86±0.38(次)、35.16±7.51(s)。对照组7月龄SAMR1小鼠第一天的学习成绩(达标次数、错误次数、全天总反应时间)分别为:8.17±2.99(次)、2.83±1.17(次)、52.57±13.79(s)。对照组7月龄SAMR1小鼠第二天的记忆成绩(达标次数、错误次数、全天总反应时间)分别为:7.67±2.50(次)、1.83±0.75(次)、44.28±11.31(s)。组间比较,实验组7月龄SAMP8小鼠与对照组7月龄SAMR1小鼠相比达标次数和错误次数增多,全天总反应时间延长,差异显著(P0.05);组内比较,实验组7月龄SAMP8小鼠较5月龄SAMP8小鼠达标次数和错误次数增多,全天总反应时间延长,差异显著(P0.05)。 2、听功能检测:实验组5、7月龄SAMP8小鼠的左耳ABR阈值(dB SPL)分别为49.3±3.59、55.1±5.09;对照组5、7月龄SAMR1小鼠的左耳ABR阈值(dB SPL)分别为34.5±5.58、46.7±5.47。实验组5、7月龄SAMP8小鼠的右耳ABR阈值(dB SPL)分别为46.1±3.53、56.3±6.17;对照组5、7月龄SAMR1小鼠的右耳ABR阈值(dB SPL)分别为37.5±6.72、47.3±2.07。组间比较,实验组7月龄SAMP8小鼠与对照组7月龄SAMR1小鼠双耳ABR阈值差异显著(P0.01);实验组5月龄SAMP8小鼠与对照组5月龄SAMR1小鼠双耳ABR阈值差异显著(P0.01);组内比较,实验组5、7月龄SAMP8小鼠双耳ABR阈值差异显著(P0.05)。 3、耳蜗毛细胞改变:耳蜗基底膜铺片光学显微镜下观察,与对照组比较,随着月龄的增加,实验组SAMP8小鼠耳蜗底回外毛细胞缺失加重;各组小鼠耳蜗底回外毛细胞平均缺失率(%)分别为:5月龄实验组SAMP8小鼠2.4±1.73、5月龄对照组SAMR1小鼠1.53±1.21;7月龄实验组SAMP8小鼠12.8±3.63、7月龄对照组SAMR1小鼠2.51±2.2。组间比较,实验组7月龄SAMP8小鼠与对照组7月龄SAMR1小鼠耳蜗底回外毛细胞平均缺失率差异显著(P0.01);组内比较,实验组5、7月龄SAMP8小鼠耳蜗底回外毛细胞平均缺失率差异显著(P0.01)。 4、耳蜗MeCP2免疫组化染色:耳蜗MeCP2免疫组化染色镜下观察,与对照组比较,随着月龄的增加,实验组SAMP8小鼠耳蜗MeCP2免疫组化染色平均光密度值降低;各组小鼠耳蜗MeCP2免疫组化染色平均光密度值分别为:5月龄实验组SAMP8小鼠38.43±12.37、5月龄对照组SAMR1小鼠43.11±10.18;7月龄实验组SAMP8小鼠27.26±4.61、7月龄对照组SAMR1小鼠42.23±9.37。组间比较,实验组7月龄SAMP8小鼠与对照组7月龄SAMR1小鼠相比,耳蜗MeCP2免疫组化染色平均光密度值明显降低,差异显著(P0.01);组内比较,实验组7月龄SAMP8小鼠较5月龄SAMP8小鼠耳蜗MeCP2免疫组化染色平均光密度值降低,差异显著(P0.05)。耳蜗螺旋神经节细胞内MeCP2免疫组化染色平均光密度值分别为:5月龄实验组SAMP8小鼠35.69±2.36、5月龄对照组SAMR1小鼠42.91±5.87;7月龄实验组SAMP8小鼠30.26±3.54、7月龄对照组SAMR1小鼠40.78±4.27。组间比较,实验组7月龄SAMP8小鼠与对照组7月龄SAMR1小鼠相比,耳蜗SGNs MeCP2免疫组化染色平均光密度值明显降低,差异显著(P0.01);实验组 5月龄SAMP8小鼠与对照组相比,耳蜗SGNs MeCP2免疫组化染色平均光密度值降低,差异显著( P0.05)。组内比较,实验组7月龄SAMP8小鼠较5月龄SAMP8小鼠耳蜗SGNs MeCP2免疫组化染色平均光密度值降低,差异显著(P0.05)。结论:SAMP8小鼠随月龄增长出现学习和记忆力下降以及听功能减退、耳蜗毛细胞缺失加重以及耳蜗MeCP2免疫组化染色阳性率降低等觉系统退行性变化特征;具有听觉系统退行性变化特征的快速老化痴呆小鼠SAMP8可以用来作为研究老年性耳聋与老年性痴呆之间是否有关联的动物模型。
[Abstract]:Objective: the purpose of this study was to investigate the age-related changes in the auditory function of Senescence accelerated dementia mouse/prone (SAMP8), intelligence and the expression of MeCP2 in the cochlear (Cochlea) tissues.
Methods: the 5,7 month old SAMP8 mice were selected as the experimental group, and the same age anti fast aging mice subline 1 (Senescence accelerated mouse/resistance 1, SAMR1) was used as the control group. The mice were tested by Y type electric maze and 8kHz short pure tone auditory brainstem response (auditory brainstem response, ABR) were used to detect their intelligence and double ear hearing function. Threshold value), the average loss rate of the left hair cells in the left cochlea was calculated by the count of silver staining hair cell count in the cochlear basement membrane, and the expression and distribution of MeCP2 protein in the right cochlea tissues of the mice of different months of age were detected by immunohistochemistry.
Results: 1, intelligence test: the results of the first day of the 5 month old SAMP8 mice in the experimental group were 8.57 + 5.97 (Times), 3.43 + 1.13 (Times), 48.47 + 15.82 (s), and second days in the experimental group 5 month old SAMP8 mice (the number of standards, the number of errors, the total reaction time of the day) were respectively: 5.14 + 3. 33 (Times), 2.71 + 0.76 (Times), 46.19 + 11.63 (s). The results of the first day of the 7 month old SAMP8 mice in the experimental group were 15.3 + 6.58 (Times), 5.20 + 1.03 (Times), 73.09 + 22.56 (s), and the memory scores of 7 month old SAMP8 mice in the experimental group (times of standard, error times, total total reaction time) The results were as follows: 11.2 + 2.39 (Times), 3.60 + 0.84 (Times), 60.05 + 12.85 (s). The results of the first day of the 5 month old SAMR1 mice in the control group were 7.29 + 2.29 (Times), 1.57 + 0.53 (Times), 46.87 + 11.44 (s). The total reaction time was 3.57 + 1.51 (Times), 0.86 + 0.38 (Times) and 35.16 + 7.51 (s). The results of the first day of the 7 month old SAMR1 mice in the control group were 8.17 + 2.99 (Times), 2.83 + 1.17 (Times), 52.57 + 13.79 (s). The number of errors and total response time of the whole day were 7.67 + 2.50 (Times), 1.83 + 0.75 (Times) and 44.28 + 11.31 (s). Compared with the control group, 7 month old SAMP8 mice were compared with the control group 7 month old SAMR1 mice, and the total response time was longer and the difference was significant (P0.05). In the group comparison, the experimental group 7 month old SAMP8 mice was compared with May. Age SAMP8 mice reached the standard number and number of errors increased, the total reaction time prolonged, the difference was significant (P0.05).
2, auditory function test: the left ear ABR threshold (dB SPL) of 5,7 month old SAMP8 mice in the experimental group was 49.3 + 3.59,55.1 + 5.09, and the left ear ABR threshold (dB SPL) of SAMR1 mice in the control group was 46.1 + 6.17, respectively, 46.1 + 6.17, respectively. The ABR threshold (dB SPL) in the right ear of the mice was 37.5 + 6.72,47.3 + 2.07., respectively. The threshold difference between the experimental group 7 month old SAMP8 mice and the control group 7 month old SAMR1 mice was significantly different (P0.01), and the experimental group 5 month old SAMP8 mice and the control group 5 month old SAMR1 mice were significantly different from the double ear ABR threshold. The difference of ABR threshold was significant (P0.05).
3, the change of cochlear hair cells: the cochlear basal membrane sheet was observed under the optical microscope. Compared with the control group, the loss of hair cells in the outer cochlea of the SAMP8 mice increased with the increase of the month old age, and the average loss rate of the outer hair cells of the cochlear bottom of the mice in each group was 1.5 in the 5 month old experimental group, 2.4 + 1.73,5 month old control group of SAMR1 mice 1.5. 3 + 1.21, 7 month old SAMP8 mice in experimental group 12.8 + 3.63,7 month old SAMR1 mice 2.51 + 2.2. group, 7 month old SAMP8 mice in the experimental group and the control group 7 month old SAMR1 mice the average loss of outer hair cells in the cochlea outer hair cells (P0.01); in the experimental group, the average loss rate difference of the outer hair cell of the cochlear bottom of the experimental group of 5,7 month old mice Significant (P0.01).
4, cochlear MeCP2 immunohistochemical staining: cochlear MeCP2 immunohistochemical staining microscope, compared with the control group, with the increase of age, the average light density of the SAMP8 mouse cochlea MeCP2 immunohistochemical staining decreased, and the average density of the MeCP2 immunohistochemical staining of the cochlea of mice in each group was 38.43 + 12.37,5 in the 5 month old experimental group, respectively. The SAMR1 mice in the month old control group were 43.11 + 10.18, and the 27.26 + 4.61,7 month old control group of SAMP8 mice in the experimental group was compared with the 42.23 + 9.37. group of the control group of 27.26 + 4.61,7 months old. The average light density of the cochlear MeCP2 immunohistochemical staining in the 7 month old SAMP8 mice in the experimental group was significantly lower than the control group 7 month old SAMR1 mice, and the difference was significant (P0.01); the group was compared with the experimental group 7. Compared with 5 month old SAMP8 mice, the mean optical density of MeCP2 in the SAMP8 cochlea of month old mice decreased significantly (P0.05).
The average optical density values of MeCP2 immunohistochemical staining in cochlear spiral ganglion cells were: 5 month old SAMP8 mice in experimental group 35.69 + 2.36,5 month old control group SAMR1 mice 42.91 + 5.87, 7 month old experimental group 30.26 + 3.54,7 month old control group SAMR1 mice 40.78 + 4.27. group comparison, the experimental group 7 month old SAMP8 mice and the control group 7 month old SAM. Compared with R1 mice, the average optical density of SGNs MeCP2 in cochlea decreased significantly (P0.01).
5 month old SAMP8 mice compared with the control group, the average light density of the cochlea SGNs MeCP2 immunohistochemical staining decreased significantly (P0.05). In the group comparison, the average light density value of the 7 month old SAMP8 mice in the experimental group was lower than that of the 5 month old SAMP8 mouse cochlea SGNs MeCP2. The difference was significant (P0.05).
Conclusion: the decline of learning and memory, hearing loss, loss of auditory function, aggravation of cochlear hair cell loss and the decrease of positive rate of MeCP2 immunohistochemical staining in the cochlea decreased with the growth of SAMP8 mice. The rapid aging dementia mouse SAMP8 with the characteristics of the degeneration of the auditory system could be used as a study of the elderly. Animal models of association between deafness and Alzheimer's disease.
【学位授予单位】：桂林医学院
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：R764.436

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