顺铂对耳蜗螺旋神经节细胞毒性作用及机制

目的通过透射电镜及免疫组化法观察顺铂对耳蜗螺旋神经节细胞的毒性作用。方法16只豚鼠随机均分为2组。顺铂组连续5天腹腔注射顺铂2mg/kg/d;对照组连续5天腹腔注射生理盐水2mg/kg/d;用药前后测试听力,处死动物后制作耳蜗标本,透射电镜观察及免疫组化法测定诱导型一氧化氮合酶(induciblenitricoxidesynthase,iNOS)的表达。结果ABR:顺铂组听力下降明显,阈值显著升高(P<0.01)。透射电镜观察:顺铂组螺旋神经节细胞的细胞器损伤严重,核变形,线粒体肿胀,大量空泡样变,粗面内质网增多,有髓神经纤维的髓鞘增厚;对照组螺旋神经节细胞核无变形,核仁基本居中,线粒体结构正常。免疫组织化学显示:顺铂组螺旋神经节有iNOS阳性反应显色,灰度值降低,iNOS活性升高,与对照组比较,有显著性差异(P<0.01)。结论顺铂可致耳蜗螺旋神经节细胞损伤并呈iNOS阳性表达,导致听力下降。

TEM observation and iNOS expression in cochlea spiral ganglion cell injured by cisplatin

OBJECTIVE To study oto-toxicity caused by cisplatin with transmission electron microscope (TEM) and immunohistochemisty. METHODS Sixteen guinea pigs were randomly divided into two groups. Cisplatin group: guinea pigs were treated with intrap- eritoneal injection of cisplatin (2 mg/kg/d) for 5 days. Control group: animals were treated with intraperitoneal in- jection of normal saline (2 mg/kg/d) for 5 days. Auditory threshold was tested before and after experiment for all the animals. Animals were sacrificed and cochleas were taken for study. Samples were observed through TEM and ex- pression of iNOS was tested by immunohistochemical method combined with image quantitative analysis technique. RESULTS Test of auditory threshold: auditory function of cisplatin group was injured severely and ABR threshold el- evated significantly (P < 0.01). The ultrastructural changes of spiral ganglion cell (SGC): cellular organs of SGC were damaged severely in cisplatin group. Nucleoli were distorted, mitochondrias were swelled, bubble degeneration appeared in many of them. The number of rough endoplasmic reticu- lum (REM) was increased, neurilemma of the nerve fiber became thicker. In control group, the nucleoli of SGC were not distorted, nucleolus lay in the center, and the structure of mitochondria was normal. Immunohis- tochemical study showed that iNOS masculine reaction staining appeared in cisplatin group samples. The grey value in cisplatin treated sample was lower and iNOS activity was higher than that in control group (P < 0.01). CONCLUSION Cisplatin could increase expression of iNOS and destroyed SGC in cochlea. [