60Co照射后豚鼠内耳前庭终器毛细胞损伤及凋亡的实验研究

目的:探讨60 Co照射后豚鼠内耳前庭终器损伤与caspase-3、bax及bcl-2表达的关系及照射后前庭功能的损伤情况。方法:将白化豚鼠40只随机分为正常对照组和照射组(1,4,14,30d组),每组8只。照射组豚鼠右耳颞部做一次性60 Coγ射线照射40Gy。分别于照射前、照射后1,4,14d及30d行冰水试验后处死,取出听泡,行前庭终器切片、HE染色、免疫组化染色,并分离囊斑及壶腹嵴,行超薄切片透射电镜检查。结果:冰水试验照射组眼震时间较对照组缩短,差异有统计学意义(P<0.05),照射后30d组眼震时间较其他照射组长,差异有统计学意义(P<0.05)。照射组豚鼠的囊斑较对照组感觉上皮层厚度变薄,毛细胞数量减少,纤毛变短、减少,照射组壶腹嵴耳石层消失,纤毛消失。透射电镜显示,照射后各组的囊斑及壶腹嵴均可见受损的毛细胞,受损毛细胞线粒体肿胀,以30d为明显,线粒体嵴变短减少并且发生断裂。照射后各组囊斑caspase-3、bax、bcl-2表达较对照组增强,差异有统计学意义(P<0.05)。照射后30d组囊斑、壶腹嵴caspase-3表达强度较其他对照组减弱,差异有统计学意义(P<0.05)。照射后4d组囊斑、壶腹嵴bax表达上调程度较bcl-2表达上调程度强,差异有统计学意义(P<0.05),bax/bcl-2上升。照射后30d组囊斑、壶腹嵴bcl-2的上调程度较bax表达上调程度强,差异有统计学意义(P<0.05),bax/bcl-2下降。结论:凋亡相关蛋白caspase-3的表达上调及bax、bcl-2的不均衡表达上调可能在60 Coγ射线造成的前庭损伤中起重要作用。

INJURY AND APOPTOSIS IN VESTIBULAR APPARATUS OF INNER EAR IN GUINEA PIGS AFTER 60Co IRRADIATION

Objective:To explore the damage of vestibular inner ear after 60Co irradiation and the relationship of vestibular apparatus injury and caspase-3,bax and bcl-2.Methods: Forty guinea pigs were randomly divided into 5 groups,including control(N) and radiation groups(D1,D4,D14 and D30).The right ear of the guinea pigs was radiated.The guinea pigs were sacrificed on days 1,4,14 and 30 after irradiation of 40 Gy.Before sacrificed the guinea pigs were given ice water irrigation.After sacrificed all specimens were dehydrated,cryoembedded in paraffin,serially cutted into 4 μm slices.Sections were stained with haematoxylin and eosin,immunohistochemistry and for light microscopic examination.Transmission electron microscopy was also used to examine the hierarchy of vestibular hair cells.Results: When given ice water irrigation,the horizontal nystagmus time of irradiational groups decreased compared with the control group.The horizontal nystagmus time on 30 days after irradiation increased compared with other irradiational groups.Compared with the control group,the expression of caspase-3,bax and bcl-2 of macula utriculi and crista ampullaris was higher in the irradiational groups.Compared with other irradiational groups,the expression of caspase-3 of macula utriculi and crista ampullaris of D30 group was lower.The expression of bax of macula utriculi and crista ampullaris was much higher than that of bcl-2 of group D4,bax/bcl-2 increased.The expression of bcl-2 of macula utriculi and crista ampullaris was much higher than that of bax on group D30,bax/bcl-2 decreased.Conclusion: Caspase-3 plays an important role in the injury of vestibular function which causes by the irradiation of 60Co.The unbalance expression between bax and bcl-2 may play an important role in the injury which caused by irradiation of 60Co on vestibular apparatus.