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Vicki Chrysostomou, Jelena M. Kezic, Ian A. Trounce, Jonathan G. Crowston; Exercise Protects Aged Retinal Ganglion Cells from Pressure-Induced Injury. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4679.
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We have previously shown that aging in mice increases the vulnerability of retinal ganglion cells to pressure-induced injury. Here, we test if exercise can modify the response of aged retinal ganglion cells to acute IOP elevation.
At 12 months of age, mice were assigned to exercise (EX) or control (CONT) groups (n=12 per group). EX mice performed 6 weeks of swimming (1 hr/day, 5 days/wk) and CONT mice were housed under standard conditions before being subject to unilateral IOP elevation (50 mmHg, 30 min). Retinal ganglion cell function was assessed before and after IOP elevation with the positive scotopic threshold response (pSTR) component of the electroretinogram. Retinas were assessed for mRNA levels using quantitative PCR and for inflammatory cells using immunohistochemistry.
EX mice showed significantly (P=0.007) less retinal ganglion cell dysfunction in response to IOP elevation compared with CONT mice. One week after IOP challenge, pSTR amplitudes in EX mice were 86.2% of baseline compared to 44.6% in CONT mice. In addition to reducing functional loss, exercise ameliorated pressure-induced biochemical changes in the retina. Compared to IOP-challenged CONT retinas, EX retinas showed significantly (i) lower mRNA levels of the stress response protein GFAP (n=7, P=0.004), (ii) higher mRNA levels of the retinal ganglion cell-specific protein Thy1 (n=7, P=0.008), and (iii) reduced overall numbers and percentage of activated Iba-1+ cells (n=4, P<0.05).
Exercise, begun late in life in the mouse, increases the resistance of the retina to pressure-induced injury.
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