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T.H. Nguyen, Y. Umino, T. Loi, R. Barlow; Metabolic Modulation of Mouse Retinal Sensitivity . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1596.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Investigate how changes in body temperature and blood glucose affect retinal sensitivity in mouse. Methods:Dark–adapted C57BL/6J mice were anesthetized with Nembutal (5mg/ml: 60mg/kg), pupils dilated with Tropicamide, and corneas moistened with 3% methyl–cellulose. Using a unipolar Burian Allen electrode or a small silver wire loop, ERGs were recorded (100gain, 0.3–300Hz) in response to 10–ms flashes delivered under computer control LEDs (520nm) placed 1cm from the cornea. Body temperature was modulated with a heating pad and monitored with a rectal thermometer. Blood glucose level was modulated by fasting and IP injections of dextrose (5%) and measured from the tail vein with a OneTouch Ultra glucose meter. Retinal circulation was observed with a scanning laser ophthalmoscope (Lin et al, 2004 ARVO Abstract #2786). Results: Lowering body temperature of fed adult mice (>0.5yr) by 100C slowed the ERG but did not affect its amplitude. Repeating the experiment on fasted animals slowed and reduced the ERG as well as lowered blood glucose levels in most cases. Alleviating an animal’s hypoglycemia via IP dextrose injection can restore the ERG without affecting the animal’s hypothermia. None of these experimental conditions significantly changed retinal blood flow as observed with SLO. Conclusions: Short–term metabolic stress caused by low blood glucose and/or low body temperature can decrease retinal sensitivity. The modulatory effect of exogenous glucose on retinal sensitivity appears to depend on the animal’s metabolic state. The relative contributions of glycolysis and oxidative metabolism to retinal sensitivity under such stress conditions are not known.
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