OBJECTIVETo investigate the protective effect of progesterone against high intraocular pressure-induced ischemia-reperfusion (IR) injury.

METHODSTwenty-four SD rats were randomly divided into normal control, IR model, dimethyl sulfoxide (DMSO) solvent treatment group, and progesterone treatment group. In the latter 3 groups, retinal IR injury was induced by intraocular injection of saline. In the progesterone group, intraperitoneal injections of 4 mg/kg progesterone were administered 30 min before and 2 h after ischemia, and an equivalent volume of DMSO was used in the DMSO group. The content of malondialdehyde (MDA) and superoxide dismutase (SOD) activity were measured by spectrophotometer after the treatment, and the pathological changes of the retina were observed by transmission electron microscope and light microscope.

RESULTSSix hours after reperfusion, the content of MDA in the model group was significantly higher than that in the normal control group (P<0.01), but lower than that in progesterone treatment group (P<0.01); reverse changes in SOD activity was observed. In the model group, the inner nuclear layer and nerve fiber layer became thinner with obvious cellular pathologies including nuclear condensation, mitochondria vacuolization and endocytoplasmic reticulum swelling. Progesterone treatment markedly alleviated these pathologies in the inner nuclear layer and nerve fiber layer of the retina.

CONCLUSIONProgesterone offers protection of the retina against IR injury in SD rats by increasing SOD activity and decreasing MDA content in the retina.