September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
In vivo measurement of increased vascular permeability after STZ induction of diabetes in rats by fluorescence angiography using the Micron IV
Author Affiliations & Notes
  • Claire Louise Allen
    Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
  • David O Bates
    Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
  • Footnotes
    Commercial Relationships   Claire Allen, None; David Bates, None
  • Footnotes
    Support   Diabetes UK Grant RA4841
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 4527. doi:
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      Claire Louise Allen, David O Bates; In vivo measurement of increased vascular permeability after STZ induction of diabetes in rats by fluorescence angiography using the Micron IV. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4527.

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

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Abstract

Purpose : Diabetic retinopathy (DR) is a major complication of diabetes and a leading causes of blindness worldwide. Chemically induced diabetic rodent models mimic some phenotypic changes in DR, but quantitative assessment of the increase in vascular permeability seen in diabetes usually requires terminal experiments, and are not easily imaged non-invasively using fluorescein angiography. The Micron IV (Phoenix Research Labs) rodent specific retinal in vivo imaging system provides enhanced sensitivity, signal processing, resolution, real-time capture and high throughput compared to comparably priced systems. This study tests the hypothesis that retinal vascular leakage can be assessed in vivo over time and in the same focal area using the Micron IV.

Methods : FFA was carried out in non-diabetic and diabetic Norway Brown rats (250-300g) on day 0 and 7 using the Micron IV. Following a 16hr fasting period animals received a single dose of PBS (n=6) or streptozotocin 50mg/kg (n=6) i.p. on day 1 and given access to a 15% sucrose solution (24hrs) and water. Angiograms were converted from virtual stacks to 8-bit images in ImageJ and the intensity of sodium fluorescein in specified areas of the vascular interstitium and the retinal vessel were measured over time. The ratio of interstitial to vascular fluorescence intensities were adjusted for background levels and plotted against time to give rate of increase in intensity per unit time (solute flux, or leak).

Results : Diabetes was successfully induced in rats following a single dose of STZ and the animals maintained for 1 week without insulin supplementation. Retinal vascular leak was measured in the same focal position of the retina on day 0 and 7 using the micron IV. Retinal leak was shown to significantly increase (p <0.05) in the STZ induced diabetic group (13.3 ± 3.30 x10-4.s-1) compared to non-diabetic controls (7.5 ± 3.7 x10-4 .s-1), on day 7. This was further supported by fundus images showing increased capillary leakage and the formation of multiple micro aneurysms in the retina.

Conclusions : The Micron IV provides a standardised, enhanced, real-time and high-throughput platform to measure retinal permeability in a rat model of diabetes. Advanced quantitative assessments such as this could substantially contribute to a better understanding of the pathogenesis of DR and identify potential drugs for treatment.

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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