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Kenichi Kohzaki, Algis J. Vingrys, Bang V. Bui; Early Inner Retinal Dysfunction in Streptozotocin-Induced Diabetic Rats. Invest. Ophthalmol. Vis. Sci. 2008;49(8):3595-3604. doi: 10.1167/iovs.08-1679.
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purpose. Diabetes is known to alter retinal function, as measured with the electroretinogram (ERG), which shows a propensity toward inner retinal oscillatory potential (OPs) abnormalities. However, the effect that diabetes has on other ganglion cell–related responses is not known. This study was a systematic evaluation of streptozotocin (STZ) diabetes–related ERG changes in rats for the first 11 weeks after diabetogenesis.
methods. Thirty Sprague-Dawley rats were randomly assigned to treated (50 mg/kg STZ (n = 16) and control groups (1 mL/kg citrate buffer, n = 14) at 6 weeks of age. Two control animals and four STZ animals were excluded because of blood glucose criteria or systemic complications. Diabetic animals were given daily SC injections of 1 to 2 units of long-acting insulin. ERGs were measured at 4, 8, and 11 weeks after treatment. The a-wave was used as an index of outer retinal function, whereas the b-wave, OPs, and the scotopic threshold response (STR) were used as indices of inner retinal function.
results. Photoreceptoral (a-wave) and bipolar cell (b-wave) responses were not significantly reduced by STZ treatment. OPs were significantly reduced by 8 weeks (−25% ± 7%, P < 0.05). The most severely affected component was the ganglion cell–dominated positive STR, which was significantly decreased from the first time point (−51% ± 11% at 4 weeks, P < 0.05), but the negative component was unaffected over the 11-week period.
conclusions. The ganglion cell dominated pSTR showed large losses in STZ treated rats.
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