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Sanja B. Turturro, Jennifer J. Kang-Mieler; Comparison Of Retinal Hemodynamics Of Insulin-treated Diabetic Animals And Non-treated Diabetic Animals In Early Stages Of Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5962.
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© ARVO (1962-2015); The Authors (2016-present)
The objective of this study was to evaluate retinal hemodynamic changes in insulin-treated diabetic animals and non-treated diabetic animals in early stages of diabetic retinopathy.
Streptozotocin (65mg/ml/kg in 0.1 M citrate buffer, pH=4.5) was injected intravenously to induce diabetes in anesthetized Long-Evans rats. After confirming the onset of diabetes at week 1, two insulin implants (~ 2U/24 hrs/implant) were administered subcutaneously in a treatment group (‘insulin-treated diabetic, ITD’, n=5 rats). Another group of diabetic animals did not receive any treatment (‘non-treated diabetic, NTD’, n=5 rats). Additionally, a group of healthy animals was used as control (‘control’, n=2 rats). Infrared reflectance (IR) images were acquired using a Scanning Laser Ophthalmoscope (SLO) to measure average diameter of arterial and venous vessels. SLO fluorescein angiography (FA) movies of 1µm yellow-green fluorescent microspheres (505nm maximum absorption and 515 nm maximum emission) were obtained to measure retinal blood velocity. The average diameter and average blood velocity were used to calculate average volumetric blood flow (VBF). The animals were monitored weekly for up to eight weeks.
NTD animals showed significant hyperglycemia (>500 mg/dL) and weight loss throughout the investigated time period. ITD animals exhibited weight gain but the glucose levels maintained below 350mg/dL. By week 6 post onset of diabetes, ITD animals, in comparison to control animals, showed no change in arterial and venous average diameters. NTD animals, in comparison to control animals, exhibited ~10% and ~9% decrease in arterial and venous average diameters, respectively. The arterial and venous average velocity for all three animal groups remained relatively constant throughout the investigated time frame. By week 6 post onset of diabetes, the arterial and venous average VBF of ITD animals showed no change in comparison to control animals. However, NTD animals showed ~21% and ~28% decrease in arterial and venous average VBF, respectively, in comparison to control animals.
By 6 weeks post onset of diabetes, retinal hemodynamics of ITD animals demonstrated similar trend as control animals, however, NTD animals showed a decreasing trend in average diameters and average VBF. The results suggest that un-controlled glucose levels may be a contributing factor in retinal hemodynamic changes in early stages of diabetic retinopathy.
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