兔眼经瞳孔温热疗法阈值能量治疗的组织病理反应和细胞凋亡

Observation of pathological reactions and apoptosis of rabbit's retinal cells induced by transpupillary thermotherapy with threshold power

目的:观察兔眼视网膜经瞳孔温热疗法(transpupillary thermotherapy,TTT)阈值能量照射后组织病理反应和细胞凋亡情况。方法:健康青紫兰兔20只,采用阈值能量对实验眼采用1.2mm光斑的810nm激光照射60s。采用眼底镜和眼底照相对光斑进行形态学研究,采用光镜和电镜的方法研究光斑的组织病理和超微结构的改变,采用TUNEL法、荧光素标记AnnexinⅤ-FITC/PI双染色流式细胞测定法观察视网膜细胞的凋亡。结果:TTT后1d可见视网膜轻度灰白色水肿,后视网膜逐渐出现色素沉着。组织病理学切片显示神经节细胞无显著性破坏。TUNEL染色可见视网膜全层均有细胞凋亡的发生,以内颗粒层为主,流式细胞双染测定显示以凋亡为主。结论:阈能级TTT照射未引起神经节细胞严重损伤,较安全,其作用机制以细胞凋亡为主。

AIM： To observe pathological reactions and apoptosis of rabbits＇ retinal cells induced by transpupillary thermotherapy （TTT） with threshold power. METHODS： TranspupUlary therrnotherapy （TTT） was performed on eyes of 20 young healthy pigmented rabbits with 1.2 mm spot size and 60s irradiation by threshold power. We observed morphology of spots with funduscope and fundus photography, histopathological changes and ultrastructure of spots with light microscope and electron microscope, and apoptosis of retinal cells with terminal deoxynucleotidyl transferase mediated dUTP nick end labeling, Annexin V-fluorescein isothiocyanate/ Propidium iodide labeling and flow cytometry. RESULTS： Retinal whitening and edema could be found at majority of the laser spots on the 1st day after -TTT, afterward pigment deposition presented on the retina. Ganglion cells can be observed without obvious destruction in histopathological sections, it was observed that apoptosis appeared in all fundus layers （mostly in inner nudear layer） with TUNEL, and most apoptotic cells in early period of post-irradiation with Annexin V-FITC/PI. CONCLUSIONS： Threshold TTT may cause little ganglion cell damage, and its main mechanism is apoptosis, so threshold TTT is relatively safe.