Abstract
Abstract: :
Purpose: Recently, nitric oxide (NO) has received much attention as an important mediator with pathologic roles in glaucoma. Excessive NO, particularly synthesized by NOS-2 in retinal Muller cells, may be neurodestructive in patients with glaucoma. In this report, we studied NOS-2 mRNA induction and NO production in Muller cells in response to elevated pressure. Methods: Muller cells were obtained from enucleated rat eyes at postnatal day 6 to 8. Cell were seeded into dishes, and maintained at 37ºC in humidified atmosphere containing 5% CO2 and 95% air. To investigate the effect of elevated pressure in the gene transcription of NOS-2, Muller Cells were placed in sealed chamber at elevated pressure (+152mmHg)for 2 hours. The induction of NOS-2 was evaluated by RT-PCR. NO production was also evaluated with DAF (diaminofluorescein-2). Results: Immediately after exposing to elevated pressure, mRNA level of NOS-2 did not change compared with control. When maintained at the atmospheric pressure, mRNA level of NOS-2 showed approximately 4-fold increased at 2 hours. At 4 hours, it decreased to the control level. NO production monitored by DAF also showed similar time course. Conclusion: NOS-2 in Muller cells was induced by elevated pressure in vitro. The excessive NO produced by NOS-2 in Muller cell is neurodestructive and may contribute to retinal ganglion cell damage.
Keywords: 491 nitric oxide • 479 Muller cells • 489 neuroprotection