AIM: To observe morphological changes of retinal tissues, early apoptosis rates and expressions of caspase-3 and p53 in rats, so as to analyze the mechanism of apoptosis in retinal damage of rats under stimulated hypoxic conditions at high altitude.

METHODS: Experimental rats were randomly divided into the control and experimental groups. Ten rats in the control group were bred in an indoor environment with the altitude of 1,500 meters; 60 in the experimental group were divided into 6 groups with each group of 10 rats, which were bred in a simulated experimental cabin of a simulated plateau environment with the altitude of 5,000 meters for 2, 6, 12, 24, 48 and 72h, respectively. After rats were killed in all groups, pathomorphological changes of rats' retinas were observed with hematoxylin eosin staining, expressions of caspase-3 and p53 in rats' retinas were noticed with immunohistochemical staining, and flow cytometry was used to detect early apoptosis rates.

RESULTS: The simulated hypoxic conditions at high altitude could cause rats' retinal tissues damage, and the longer hypoxic conditions were, the more obvious retinal pathological damage was. Expressions of caspase-3 and p53 were detected at 2h, and gradually increased with oxygen lack time increasing, the differences showed statistical significance(P<0.05). Early apoptosis rates of retinal cells gradually rose with oxygen lack time, and rose obviously at 48h.

CONCLUSION: Apoptosis may involve in the mechanism of rats' retinal damage induced by stimulated hypoxic conditions at high altitude, and play this role by the caspase-3-dependent apoptotic pathway.