PURPOSE: To evaluate the expression of the Na(+)-K(+)-2Cl(-)-cotransporter 2 (NKCC2) in the ischemic rat retina. METHODS: Retinal ischemia was induced by pressures 90 to 120 mmHg, above systemic systolic pressure. Immunohistochemistry and western blot analysis were performed. RESULTS: NKCC2 is expressed in the normal retina and its expression is increased by ischemia caused by intraocular pressure elevation. NKCC2 immunoreactivity was observed mainly in axon bundles of ganglion cells and horizontal cell processes in the retina. NKCC2 expression continuously increased with a peak value 3 days (to 415% of normal levels) after ischemic injury, and then gradually decreased to 314% of controls until 2 weeks post injury. The mean density of NKCC2-labeled ganglion cells per mm2 changed from 1,255 +/- 109 in normal retinas to 391 +/- 49 and 185 +/- 37 at 3 days and 2 weeks after ischemia, respectively (p < 0.05), implying cell death of ganglion cells labeled with NKCC2. CONCLUSIONS: Taken together, these results suggest that NKCC2, which is expressed in retinal ganglion and horizontal cells, may contribute to cell death by ischemic injury in the retina, although the molecular mechanisms involved remain to be clarified.
Animals ; Blotting, Western ; Disease Models, Animal ; Immunohistochemistry ; Intraocular Pressure ; Ischemia/etiology/*metabolism ; Male ; Microscopy, Confocal ; Ocular Hypertension/*complications/metabolism/physiopathology ; Rats ; Rats, Sprague-Dawley ; Retinal Diseases/etiology/*metabolism ; Retinal Ganglion Cells/*metabolism/pathology ; Sodium-Potassium-Chloride Symporters/*biosynthesis

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.

Animals ; Dimethyl Sulfoxide ; Female ; Ischemia ; etiology ; pathology ; Male ; Malondialdehyde ; metabolism ; Ocular Hypertension ; complications ; Progesterone ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; etiology ; prevention & control ; Retina ; metabolism ; Retinal Vessels ; physiopathology ; Superoxide Dismutase ; metabolism