May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Photic Regulation of Heme Oxygenase Activity in the Golden Hamster Retina
Author Affiliations & Notes
  • R.E. Rosenstein
    Dept of Human Biochem, Sch of Med/Univ of Buenos Airs, Capital Federal, Argentina
  • G.B. Sacca
    Dept of Human Biochem, Sch of Med/Univ of Buenos Airs, Capital Federal, Argentina
  • L. Minces
    Dept of Human Biochem, Sch of Med/Univ of Buenos Airs, Capital Federal, Argentina
  • C.O. Jaliffa
    Dept of Human Biochem, Sch of Med/Univ of Buenos Airs, Capital Federal, Argentina
  • M.I. Keller Sarmiento
    Dept of Human Biochem, Sch of Med/Univ of Buenos Airs, Capital Federal, Argentina
  • D.A. Saenz
    Dept of Human Biochem, Sch of Med/Univ of Buenos Airs, Capital Federal, Argentina
  • Footnotes
    Commercial Relationships  R.E. Rosenstein, None; G.B. Sacca, None; L. Minces, None; C.O. Jaliffa, None; M.I. Keller Sarmiento, None; D.A. Saenz, None.
  • Footnotes
    Support  ANPCyT, Prevent Blindness America, Fight for Sight Research Division, Fundacion Antorchas, Sigma Xi
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 4571. doi:
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      R.E. Rosenstein, G.B. Sacca, L. Minces, C.O. Jaliffa, M.I. Keller Sarmiento, D.A. Saenz; Photic Regulation of Heme Oxygenase Activity in the Golden Hamster Retina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4571.

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

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Abstract

Abstract: : Purpose: To study the photic regulation of heme oxygenase activity in the golden hamster retina. Methods: Heme oxygenase (HO) activity was assessed by a spectrophotometric assay. Western blotting was employed to identify retinal HO isoforms and to assess their levels. Retinal levels of cGMP were measured by radioimmunoassay, whereas retinal thiobarbituric acid reactive substances (TBARS) levels were assessed spectrophometricaly Results: HO activity was significantly higher at midday than at midnight. When the hamsters were placed under constant darkness for 48 h and killed at subjective day or at subjective night, the differences in HO activity disappeared. Western blot analysis showed no differences in HO-2 levels among these time points, whereas HO-1 was not detected at any interval. Dopamine significantly increased HO activity in retinas excised at noon or at midnight, with a higher sensitivity during the night. The effect of dopamine was reversed by SCH 23390 but not by spiperone and clozapine and it was not reproduced by quinpirole. Two cAMP analogues (8 Br and dibutyryl-cAMP) increased HO activity being their effect as well as the effect of dopamine blocked by H-89, a PKA inhibitor. Tin-protoporphyrin IX, an HO inhibitor, significantly decreased cGMP accumulation with maximal effects during the day. Low concentrations of bilirubin decreased retinal thiobarbituric acid substances levels (an index of lipid peroxidation) in basal conditions and after exposing retinal cells to H2O2. Conclusions: These results suggest that hamster retinal HO activity is regulated by the photic stimulus, probably through a dopamine/cAMP/PKA dependent pathway. In addition, present results support that HO activity could be involved in retinal physiology and pathology.

Keywords: enzymes/enzyme inhibitors • dopamine • signal transduction 
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