Objective: To establish a main lacrimal gland extirpation xerophthalmia model and to study the relationship between expression of apoptosis genes in various ocular surface cells (cornea and conjunctiva epithelium cells and Meibomian cells) and ocular surface sicca as well as tissue damages in this model.
Methods: Twenty adult Wistar rats were included in this study and allocated to two groups randomly. Main lacrimal glands were excised in 10 animals and Schirmer I test, tear film break-up time (BUT) and fluorescence staining were performed before the operation and 3 days, 1, 2, 4, 8 and 12 weeks after the operation. Ten experimental animals and ten normal animals in the control group were investigated by immunohistochemistry staining of the cornea, conjunctivas epithelium cells and Meibomian cells to detect the expression of Bax and Bcl-2 gene.
Results: Schirmer I test and BUT were significantly lower in the experimental group 1-2 weeks after the operation. The difference became more prominent in the course of observation (P < 0.05). Fluorescence staining was positive in the experimental group. Cornea, conjunctival epithelial cells and Meibomian cells showed more increased expression of Bax in the experimental group [(503.47 +/- 343.73), (586.36 +/- 296.47), (436.61 +/- 246.96) every thousands cells] than that in the normal controls [(241.71 +/- 130.12), (311.03 +/- 142.33), (202.16 +/- 109.29) every thousands cells] (P < 0.05). Bcl-2 expression was decreased in the experimental group [(237.32 +/- 87.07), (236.07 +/- 81.24), (251.79 +/- 89.93) every thousands cells] as compared to the normal controls [(474.24 +/- 167.62), (342.81 +/- 114.57), (320.42 +/- 153.32) every thousands cells] (P < 0.05).
Conclusions: The apoptosis of the epithelial cells in cornea, conjunctiva and Meibomian cells may be one of the mechanisms lead to the destruction of ocular surface tissues in xerophthalmia.