May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Effect of Ocular Hypertension on Retinal Nitridergic Pathway Activity
Author Affiliations & Notes
  • M. C. Moreno
    Human Biochemistry-Sch Med, University of Buenos Aires, Buenos Aires, Argentina
  • N. A. Belforte
    Human Biochemistry-Sch Med, University of Buenos Aires, Buenos Aires, Argentina
  • C. Cymeryng
    Human Biochemistry-Sch Med, University of Buenos Aires, Buenos Aires, Argentina
  • M. Bordone
    Human Biochemistry-Sch Med, University of Buenos Aires, Buenos Aires, Argentina
  • M. Keller Sarmiento
    Human Biochemistry-Sch Med, University of Buenos Aires, Buenos Aires, Argentina
  • R. E. Rosenstein
    Human Biochemistry-Sch Med, University of Buenos Aires, Buenos Aires, Argentina
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 5547. doi:
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      M. C. Moreno, N. A. Belforte, C. Cymeryng, M. Bordone, M. Keller Sarmiento, R. E. Rosenstein; Effect of Ocular Hypertension on Retinal Nitridergic Pathway Activity. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5547.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose:: Understanding the mechanisms of neuronal cell death in glaucoma is important for devising new treatments. Excitatory amino acids, excessive Ca2+ influx, and formation of nitric oxide (NO) via NO synthase (NOS) could be involved in glaucomatous neuropathy. The aim of the present study was to examine the retinal nitridergic pathway activity in rats exposed to experimentally elevated intraocular pressure.

Methods:: Weekly injections of HA were performed unilaterally in the rat anterior chamber, whereas the contralateral eye was injected with saline solution. At 3 or 6 weeks of treatment, retinal NOS activity was assessed through the conversion of 3H-L-arginine to 3H-L-citrulline, while NOS-1, NOS-2, and NOS-3 levels were assessed by Western blotting. L-arginine uptake was measured using 3H-L-arginine, while mRNA levels of L-arginine transporters were determined by semiquantitative RT-PCR. In addition, cyclic guanosine monophosphate (cGMP) levels were quantified by radioimmunoassay

Results:: At both 3 and 6 weeks of treatment, NOS activity significantly increased in HA-injected eyes although no changes in retinal NOS-1, NOS-2, or NOS-3 levels were observed in eyes injected with HA. L-arginine influx and mRNA levels of cationic aminoacid transporter type 1 and 2 (CAT-1 and CAT-2) significantly increased in retinas from hypertensive eyes. Retinal cGMP levels significantly increased in eyes injected with HA for 3 but not 6 weeks.

Conclusions:: These results suggest a significant activation of the retinal nitridergic pathway in hypertensive eyes.

Keywords: nitric oxide • retina: neurochemistry • pathology: experimental 
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