Bcl-2和Bax在自发性糖尿病小鼠耳蜗中的表达研究

Expression of Bcl-2 and Bax in cochlea of mice with spontaneus diabetic

目的观察自发性糖尿病小鼠耳蜗组织细胞凋亡及Bcl-2和Bax基因的表达。方法非肥胖性糖尿病(non-obese,diabetes,NOD)雌鼠分为糖尿病4周组(D4组)、糖尿病12周组(D12组)和正常对照组(C组)。应用吖啶橙-碘化丙啶(AO-PI)荧光染色和DNA缺口末端原位标记法(TUNEL)检测耳蜗凋亡细胞;免疫组织化学法和Western blot技术检测Bcl-2和Bax在糖尿病耳蜗组织中的表达。结果 NOD小鼠耳蜗可见大量凋亡细胞,D12组比D4组明显增多(P<0.05);两组底回毛细胞较顶回凋亡率明显增高(P<0.05)。D4组耳蜗中Bax在细胞浆内呈阳性表达,Bcl-2在细胞核及细胞浆内均呈阳性表达;D12组Bax在细胞核及细胞浆内均呈阳性表达,而Bcl-2在细胞浆内呈阳性表达;与C组比较,D4组Bax与Bcl-2表达显著增高(P<0.05),D12组Bax表达显著增高(P<0.05),但Bcl-2表达下调(P<0.05);D4组Bax表达较D12组显著降低(P<0.05),但Bcl-2表达较D12组显著增高(P<0.05)。结论自发性糖尿病小鼠耳蜗存在明显细胞凋亡,其损伤机制与Bax表达增高及Bcl-2表达降低有关。

Objective To observe apoptosis and expression of Bcl-2 and Bax in cochlear tissue of spontaneous diabetic mice. Methods Non-obese diabetic （NOD） female mice were allocated into the 4-week-diabetic group （group D4）,12-week-diabetic （group D12） and nondiabetic control group （group C）. Acridine orange-propidium iodine （AO-PI） fluorescent staining and TdT-dUTP terminal nick-end labeling （TUNEL） were performed to detect cochlear apoptotic cells. Immunohistochemical assay and Western blot assay were used for detecting the expression of Bcl-2 and Bax in diabetic cochlear tissue. Results Apoptotic cells could be observed in the Cortis organ,spiral ganglion,stria vascularis,spiral ligament,and support cells of the diabetic groups. The apoptotic rates of hair cells in group D4 were obviously lower than those in group D12（P0.05）. In group D4,Bax was positively expressed in cytoplasm of Cortis organ,spiral ganglion,stria vascularis and spiral ligament; and Bcl-2 was positively expressed in both nuclei and cytoplasm of above sites. In group D12,Bax was positively expressed in both nuclei and cytoplasm of above sites,while Bcl-2 was expressed only in cytoplasm. Compared with group C,the expression of Bax increased significantly in both group D4 and group D12 （P0.05） while that of Bcl-2 increased significantly in group D4 （P0.05） but decreased in group D12 （P0.05）. The expression of Bax in group D4 was significantly lower than that in group D12 （P0.05） while that of Bcl-2 was reverse （P0.05）. Conclusion Apoptosis exists in cochlear tissue of spontaneous diabetic mice. The injury mechanism of apoptosis is related with the increased expression of Bax and decreased expression of Bcl-2.