Abstract
Abstract: :
Purpose: To determine whether short-term IOP elevation affects the GDH activity in the rat retina. Methods: IOP was raised in the right eye of Wistar rats (n=5 per group) by episcleral vein cauterization. IOP in the operated eyes remained approximately twice the IOP of the contralateral control eyes as measured by Tonopen-XL. GDH activity was determined spectrophotometrically in the direction of glutamate deamination. Total protein concentration was measured by the Bradford method. GDH activity per mg of protein was compared between control eyes and eyes with elevated IOP. The amount of GDH was also compared by Western blotting and immunohistochemistry. Results: GDH activity per mg of protein was significantly reduced (P < 0.05) at day 1 and at 1 week in eyes with elevated IOP compared to control eyes. Mean GDH activity per mg of protein in eyes with elevated IOP was reduced by an average of 44% on day 1 and 27% by week 1 compared to the contralateral control eyes. However, GDH activity did not differ between the two groups of eyes at two weeks. GDH immunoreactivity localized to the ganglion cell layer, inner plexiform and outer plexiform layers. No obvious difference of GDH immunoreactivity in these layers was observed after one week of elevated IOP. Conclusion: IOP elevation causes functional changes in glutamate metabolism of short duration by affecting, in addition to other enzymes, GDH activity. It appears that such changes are not necessarily caused by changes in the amount of GDH protein.
Keywords: 316 animal model • 399 enzymes/enzyme inhibitors • 554 retina