September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Glutathione release from the rat lens: implications for overall ocular health
Author Affiliations & Notes
  • Julie Lim
    Dept Physiology, School of Medical Sciences, NZ National Eye Centre, University of Auckland, Auckland, New Zealand
  • Ankita Umapathy
    Dept Physiology, School of Medical Sciences, NZ National Eye Centre, University of Auckland, Auckland, New Zealand
  • Paul J Donaldson
    Dept Physiology, School of Medical Sciences, NZ National Eye Centre, University of Auckland, Auckland, New Zealand
  • Footnotes
    Commercial Relationships   Julie Lim, None; Ankita Umapathy, None; Paul Donaldson, None
  • Footnotes
    Support  Sir Charles Hercus Health Research Fellowship, University of Auckland Doctoral Scholarship and the HOPE Foundation for Research on Ageing
Investigative Ophthalmology & Visual Science September 2016, Vol.57, No Pagination Specified. doi:
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      Julie Lim, Ankita Umapathy, Paul J Donaldson; Glutathione release from the rat lens: implications for overall ocular health
      . Invest. Ophthalmol. Vis. Sci. 201657(12):.

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

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Abstract

Purpose : To demonstrate glutathione (GSH) efflux from the rat lens and to identify and functionally characterise the molecular pathways involved.

Methods : Rat lenses were cultured in isosmotic AAH for varying amounts of time and GSH and GSSG (oxidised GSH) released into the media and retained in the lens measured. Lenses were cultured in the absence or presence of acivicin, a γ-glutamyl transpeptidase inhibitor, and GSH/GSSG measured. RT-PCR, western blotting and immunohistochemistry was used to screen and localise GSH efflux transporters which included members of the Multidrug Resistance Associated Proteins (Mrps). To test the involvement of Mrps in GSH release, lenses were cultured in the presence or absence of MK571, an Mrp-specific inhibitor, and GSH/GSSG measured. Finally, lenses were cultured in the presence of low (~10µM) or high (~70µM) levels of H2O2 and GSH/GSSG measured in the media and lenses.

Results : The lens is able to release basal levels of GSH (~125mM) under isosmotic conditions. GSH efflux was elevated in the presence of acivicin (~56% increase) indicating that GSH released from the lens undergoes some breakdown into precursor amino acids. GSH efflux was inhibited in the presence of MK571 (~73% inhibition), suggesting GSH release to be primarily mediated by Mrp transporters. Molecular screening identified Mrp1 and Mrp5 to be the most likely isoforms to mediate GSH release from the lens. In the presence of H2O2, the release of total GSH was increased (~2 fold increase) and this increase was driven by an increase in GSSG rather than GSH release.

Conclusions : The lens is able to release basal levels of GSH suggesting that it may contribute to maintaining GSH levels in the aqueous humour as well as providing amino acids for subsequent GSH synthesis to nearby tissues. During periods of oxidative stress, the lens releases GSSG which inadvertently may provide protection against oxidative stress to the corneal endothelium, which can utilise GSSG to regenerate GSH. Removal of the lens may reduce the availability of GSH, GSH precursor amino acids and GSSG to other anterior ocular tissues increasing their susceptibility to oxidative damage and the development of secondary ocular pathologies.


This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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