耳蝸缺血再灌流同時啟動了apoptotic及necrotic pathway。大量的TUNEL-positive細胞於缺血再灌流後12小時出現，TUNEL-positive細胞於72小時後開始下降；以PI染色缺氧一小時後的耳蝸毛細胞，代表apoptotic cell death的PI螢光強度於72小時後開始顯著提升且於7天後PI螢光值仍持續上升；在前面12小時在Rhodamine-Phalloidin染色下判定為cell lost(either apoptotic or necrotic cell death)的細胞比例不高，於12小時之後，內耳毛細胞的喪失(either apoptotic or necrotic cell death)則逐漸出現，在7天後失去完整形態的內耳細胞比例才會顯著增高(either apoptosis or necrosis)。耳蝸缺血再灌流造成內耳毛細胞缺氧會同時啟動內耳毛細胞的apoptitic和necrotic cell death pathway；apoptotic cell death先於necrotic cell death發生。此動物模式可作為以後分子生物學研究及新藥開發研究的基礎。
Objective: Perturbation of cochlear microcirculation is a one of the major causes of hearing impairment. The detailed cellular form after cochlear ischemia still remained to be elucidated. Therefore, we intended to examine the chronological morphological, functional, and molecular changes in the cochlea in the early stage following ischemia and reperfusion.
Methods: We developed an animal model of transient cochlear ischemia via ventral cervical approach in guinea pigs. The associated morphological, functional, and molecular changes in the cochlea were studied by rhodamine-coupled phalloidin staining, the TUNEL assay, as well as PI staining for in vivo cochlear hair cell after hypoxia.
Results: A substantial amount of TUNEL-positive cells appeared at 12 h after 1-hour of transient cochlear ischemia and declined since 72 hrs, PI positive hypoxia inner ear hair cell appears since 72 hours and the fluorescence of PI climbs through 7 days. Significant hair cell loss (either apoptosis or necrosis) appeared since 12hrs and progressed, in which apoptosis may precede the necrotic process.
Conclusions: Cochlear hair cells may exhibit both apoptotic and necrotic cell death after transient ischemia, in which apoptosis may precede the necrotic process.
