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Abstract #19121 Published in IGR 3-1
Ischemia increases prostaglandin H synthase-2 levels in retina and visual cortex in piglets
Degi R; Thore C; Bari F; Thrikawala N; Nogradi A; Robins G; Domoki F; Beasley TC; Busija DWGraefe's Archive for Clinical and Experimental Ophthalmology 2001; 239: 59-65
BACKGROUND: Ischemia increases levels of prostaglandin H synthase-2 (PGHS-2) in neonatal brain and cerebral vasculature, but effects on the developing visual system are unknown. The authors examined the effects of ischemia on PGHS-2 mRNA and protein levels in the retina and visual cortex in anesthetized piglets. METHODS: Ten minutes of complete retinal and brain ischemia was induced by increasing intracranial pressure. After two to 12 hours of reperfusion, samples of retina and visual cortex were collected for determinations of levels of PGHS-2 mRNA (RNase protection assay) or protein (immunohistochemistry and western blotting). Tissues also were obtained from control animals. RESULTS: Levels of PGHS-2 mRNA were undetectable in control animals but showed a dramatic increase at two to four hours in the cortex and retina in animals exposed to ischemia. Detectable but limited PGHS-2 immunoreactivity (IR) was present in the retina and visual cortex from control animals. In piglets not subjected to ischemia, PGHS-2 IR was localized mainly to the outer limiting membrane and to the Müller cells. Ischemia induced a marked increase in PGHS-2 IR in the neural retina, with the greatest increase in the photoreceptor layer. PGHS-2 levels in whole retina also increased at eight hours after ischemia. In the intact visual cortex, PGHS-2 IR was evident in layers II and V. Ischemia increased the intensity of IR in layers II/III as well as layer V. CONCLUSIONS: Detectable amounts of PGHS-2 protein are present in the piglet retina and visual cortex under normal conditions, but levels are markedly increased eight to 12 hours after ischemic stress. Enhanced PGHS-2 levels after ischemic stress may contribute to delayed pathological changes of the visual system in the neonate.
Dr R. Regi, Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1083, USA
Classification:
11.4 Prostaglandins (Part of: 11 Medical treatment)
