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Y. Umino, P. Amini, P. Amini, M. Abbasi, N. Abbasi, R. Barlow; Loss of Visual Sensitivity in Hypoglycemic Mice . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3168.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Examine the progressive changes in visual sensitivity in chronically hypoglycemic mice. Methods:Mice were rendered chronically hypoglycemic by null mutations of the glucagons receptor gene, Gcgr. We tested visual acuity and contrast sensitivity in homozygotes and heterozygote littermates as well as in wild type mice using an optomotor response method (Optomotry©). The stimuli consisted of vertical bars moving in a clockwise or counterclockwise direction. Using a double–blind procedure we measured visual acuity by determining the highest spatial frequency that evoked a criterion threshold response. Using the same procedure, we measured contrast sensitivity by determining an animal’s contrast threshold for a moving pattern having half the spatial frequency of the acuity measured for the animal. Results: Hypoglycemic Gcgr–/– mice and euglycemic Gcgr+/+ and Gcgr+/– mice maintain similar visual sensitivity until about 9 months of age. At that time Gcgr–/– mice begin a steady decline in vision, losing about 40% acuity and about 70% retinal sensitivity (ERG) within four months. Over the same period Gcgr+/+ and Gcgr+/– mice lose about 20% of acuity with no substantial loses in retinal sensitivity. Gcgr–/– mice also exhibited changes in contrast sensitivity that correspond well with those in visual acuity. Conclusions: Long–term metabolic stress of low blood glucose in Gcgr–/– mice causes a loss in visual sensitivity. The age–related losses of visual acuity and contrast sensitivity correlate with the age–related progression of retinal degeneration we have previously reported.
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