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Br J Ophthalmol 2004;88:816-820 doi:10.1136/bjo.2003.024661
  • Laboratory science - Scientific reports

Hypoglycaemia exacerbates ischaemic retinal injury in rats

  1. R J Casson,
  2. J P M Wood,
  3. N N Osborne
  1. Nuffield Laboratory of Ophthalmology, Oxford University, Oxford, UK
  1. Correspondence to: Professor Neville Osborne Nuffield Laboratory of Ophthalmology, Walton Street, Oxford OX2 6AW, UK; neville.osborneeye.ox.ac.uk
  • Accepted 25 June 2003

Abstract

Aims: To determine the effect of hypoglycaemia on ischaemic retinal injury.

Methods: Rat retinal cultures were incubated in varying concentrations of glucose while placed under standardised anoxic conditions, and the number of surviving GABA immunoreactive neurons was assessed using immunocytochemistry. Hypoglycaemia was induced in age and sex matched Wistar rats by an injection of rapid acting insulin. The blood, vitreous, and retinal glucose concentrations were measured using a hexokinase assay kit. Electroretinography, semiquantitative RT-PCR, and histology were used to compare the functional and structural retinal injury in these rats with the injury in appropriate controls after a period of pressure induced retinal ischaemia.

Results: Retinal cultures maintained in low glucose concentrations (<1 mM) had fewer surviving GABA immunoreactive neurons after an anoxic insult compared with retinal cultures maintained in 5 mM glucose. Hypoglycaemic rats had significantly lower vitreous glucose concentrations (0.57 (SEM 0.04) mM) than the control rats (3.1 (0.70) mM; p<0.001). The a-wave and b-wave amplitudes of the hypoglycaemic rats after 3 and 7 days of reperfusion were significantly lower than the amplitudes of the control rats. Furthermore, the level of Thy-1 mRNA (a retinal ganglion cell marker) was significantly lower in the hypoglycaemic group (p<0.001) and there was a corresponding exacerbation of structural injury compared with the controls.

Conclusion: Hypoglycaemia causes a significant reduction in vitreous glucose levels and exacerbates ischaemic retinal injury.

Footnotes

  • No financial support or commercial interests were involved in the research that culminated in this paper.

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