孕期七氟醚麻醉通过破坏耳蜗线粒体功能损伤子代小鼠听力

Sevoflurane anesthesia in pregnancy impairing the hearing of offspring mice by destroying the function of cochlear mitochondria

目的 探讨孕期七氟醚麻醉对子代小鼠听力的损伤及相关机制。方法 在孕鼠妊娠第15天(G15),将孕鼠暴露于2.5%七氟醚+100%氧气(麻醉组)或单纯100%氧气(对照组)中干预2 h。剖宫产分娩胎鼠,取耳蜗组织进行Western blot分析。在P1(出生后第1天)、P15(出生后第15天)和P30(出生后第30天)分批处死仔鼠,取耳蜗组织进行透射电镜分析。采用听性脑干反应(ABR)检测幼鼠的听阈。结果 ABR测试显示,麻醉组小鼠在4个频率(8 kHz、16 kHz、24 kHz和32 kHz)中的每一个频率都比对照组小鼠有更高的阈值。麻醉组在4个频率的波Ⅱ潜伏期均显著长于对照组(P<0.01),麻醉组波Ⅱ至波Ⅴ的峰间潜伏期在16、24和32 kHz处显著长于对照组(P<0.01)。G15孕鼠七氟醚麻醉2 h后,胎鼠耳蜗组织中caspase-3和Bcl-2的表达显著增强(P<0.001)。G15孕鼠七氟醚麻醉2 h还可引起子代小鼠耳蜗神经元和毛细胞线粒体肿胀。在P1,麻醉组耳蜗毛细胞和神经元中肿胀的线粒体数量明显多于对照组。麻醉组在P15时肿胀的线粒体质量仍然较大,但在P30时两组之间的差异不再存在。孕鼠G15时七氟醚麻醉2h可诱导胎鼠耳蜗组织中iNOS和COX-2的活化。麻醉组耳蜗组织iNOS和COX-2的表达显著高于对照组(P<0.01)。结论 孕期接触七氟醚可通过破坏耳蜗线粒体结构及功能,对子代小鼠发育中的听觉系统造成损伤。

Objective To investigate the hearing damage of offspring mice induced by sevoflurane anesthesia during pregnancy and its related mechanism. Methods On the 15th day of pregnancy(G15), pregnant rats were exposed to 2.5% sevoflurane+100% oxygen(anaesthesia group) or 100% oxygen alone(control group) for 2 h. The cochlear tissues of fetal rats delivered by cesarean section were analyzed by Western blot. The young rats were sacrificed at P1(the first day after birth),P15(the 15th day after birth) and P30(the 30th day after birth). The cochlear tissues of young rats were analyzed by transmission electron microscope(TEM). The auditory brainstem response(ABR) was used to detect the hearing threshold of the young rats. Results ABR test showed that each of the four frequencies(8 kHz, 16 kHz, 24 kHz, 32 kHz) in the anesthetized group had a higher threshold than that in the control group. The latency of wave II in the anesthesia group of the four frequencies was significantly longer than that in the control group(P<0.01). And the peak to peak latency of wave II to V in the anesthesia group was significantly longer than that in the control group at 16, 24 and 32 kHz(P<0.01). Two hours after sevoflurane anesthesia in G15 pregnant rats, the expressions of caspase-3 and Bcl-2 in cochlea of fetal rats significantly increased(P<0.001). Sevoflurane anesthesia for 2 h in G15 pregnant rats also caused swelling of cochlear neurons and hair cell mitochondria in offspring rats. In P1, the number of swollen mitochondria in cochlear hair cells and neurons in the anesthesia group was higher than that in the control group. The swollen mitochondrial mass in the anesthesia group was still large at p15, but the difference between the two groups no longer existed at P30. The activation of iNOS and COX-2 in fetal rat cochlea could be induced by sevoflurane anesthesia for 2 h at G15. The expressions of iNOS and COX-2 in cochlea of anesthesia group were significantly higher than those of control group(P<0.01). Conclusion Exposure to sevoflurane during pregnancy can damage the developing auditory system of offspring mice by destroying the structure and function of cochlear mitochondria.