宫内慢性缺氧对子代大鼠Cx26表达及内耳发育改变的研究

Study on changes of Cx26 expression level and inner ear development of offspring rats with chronic intrauterine hypoxia

目的探讨SD大鼠孕期宫内慢性缺氧(CIH)后,其子代大鼠(简称为子鼠)内耳Cx26表达水平及内耳发育改变。方法选择12只健康SD孕大鼠为研究对象,并随机分为CIH组及正常组,每组各6只。对CIH组建立CIH孕鼠模型。统计学比较两组子鼠生后不同日龄的体质量差异,并在两组子鼠日龄为56d时获取其内耳标本,分别采用光镜(HE染色)及电镜观察子鼠内耳毛细胞发育改变,采用原位细胞凋亡检测(TUNEL)法检测内耳考蒂器毛细胞凋亡情况。蛋白质印迹法比较子鼠内耳Cx26表达水平改变。结果 1 CIH组新生子鼠生后12h内,体质量显著低于正常组子鼠,且差异有统计学意义[(4.8±0.6)g vs(6.0±0.4)g,t=4.076,P=0.002]。2光镜及电镜检查结果显示,CIH组考蒂器毛细胞缺失,电镜下可见毛细胞凋亡现象;CIH组子鼠耳蜗考蒂器毛细胞、血管纹细胞及螺旋神经节平均相对光密度值,均较正常组显著增高,且差异均有统计学意义[(0.42±0.11)vs(0.26±0.09),t=2.758,P=0.020 0;(0.40±0.14)vs(0.19±0.05),t=3.460,P=0.006 0;(0.45±0.12)vs(0.19±0.03),t=5.149,P=0.000 4]。3 CIH组子鼠内耳Cx26蛋白表达水平较正常组显著降低,且差异有统计学意义[(0.72±0.36)mg/(kg·d)vs(1.07±0.19)mg/(kg·d),t=0.785,P=0.042]。结论 SD大鼠产前发生CIH,可导致胎鼠宫内生长受限、子鼠低出生体质量及听力损伤。

Objective To study the changes of connexin-26 （Cx26） expression level and inner ear development of offspring rats after SD pregnant rats suffering from chronic intrauterine hypoxia（CIH） in gestation period. Methods A total of 12 healthy SD pregnant rats were chosen as research objects and randomly divided into CIH group and normal group, each consisted 6 SD pregnant rats. CIH pregnant rat models were established for the CIH group. Compared the postnatal weight of different days of offspring rats between two groups statistically and inner ear specimen of offspring rats were extracted on the 56th day after born. Light microscope （HE staining） and electron microscope were used to observe the changes of hair cell development in inner ears. In Situ Nick-End Labeling（TUNEL） mdthod was used to detect the apoptosis of hair cells in corti organ. Western blotting method was used to detect the changes of Cx26 protein expression level in inner ears. Results ① The weight of newborn offspring rats within 12 hours after birth in CIH group was lower than that of normal group,and the difference was statistically significant [（4. 8±0. 6） g vs （6.0±0.4） g,t=4. 076,P=0. 002].② The results of light and electron microscopic examination showed that the hair cells in corti organ were deficient and apoptosis could be seen under the electron microscope in CIH group. The relative value of mean optical density of corti organ hair cells, stria vascularis cells and spiral ganglion in cochlear of CIH group were higher than those of normal group, and the differences were statistically significant[（0.42±0.11） vs （0.26±0.09） ,t=2. 758,P=0. 020 0; （0.40±0.14） vs （0.19±0.05）, t=3. 460, P=0. 006 0; （0.45±0.12） vs （0.19±0.03）, t=5. 149, P=0. 000 42. ③ The expressionlevel of Cx26 protein of offspring rats of CIH group were lower than that of normal group,and the difference was statistically significant[（0. 72± 0. 36） mg/（kg ·d） vs （1.07 ±0. 19） mg/（kg· d）, t = 0. 785, P= 0. 042]. Conclusions Prenatal CIH of SD rats results in intrauterine growth restriction o{ fetal rats, there{ore,offspring rats are born with low birth weight and suffer from hearing damage.