Purchase this article with an account.
Lukas Mees, Monica Coulter, Micah A Chrenek, Cara Tessia Motz, Erica Landis, Jeffrey H Boatright, Machelle T Pardue; Low-to-moderate intensity forced exercise protects retinal function from light-induced retinal degeneration. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5890.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Exercise has been shown to be protective against light induced retinal degeneration (LIRD) in mice. However, the exercise intensity that produces the most benefit is unknown. We tested the hypothesis that higher treadmill running speeds provide greater protection to retinal function in mice undergoing LIRD.
Two-month old male BALB/c mice were assigned to one of two control groups (naïve, inactive+LIRD) or three active groups at varying treadmill running speeds for one hour: 5 m/min (low+LIRD), 10 m/min (med+LIRD), and 20 m/min (high+LIRD). Inactive mice were placed on static treadmills. Following two weeks of exercise, mice were either left in maintenance housing light (naïve) or exposed to toxic bright light (10,000 lux; LIRD) for 4 hours. Mice were then exercised for an additional five days, at which point retinal function was assessed by electroretinogram (ERG). Animals were then sacrificed and levels of cathepsin B (CTSB) and brain-derived neurotrophic factor (BDNF) protein were analyzed by enzyme-linked immunosorbent assay (ELISA).
Mice in the low+LIRD or med+LIRD groups had significantly greater bright flash ERG amplitudes compared to inactive+LIRD mice: scotopic a-waves (low+LIRD: 3.8X greater, p=0.004; med+LIRD: 4.48X, p<0.001), scotopic b-waves (low: 3.92X, p<0.001; med: 4.39X, p<0.001), photopic b-waves (low: 3.55X, p<0.001; med: 3.56X, p<0.001) and flicker (low: 3.18X, p=0.005; med: 3.59X, p=0.02). Mice in the high+LIRD group were indistinguishable from inactive+LIRD on all ERG parameters. As expected, naïve mice showed the greatest amplitudes on all waves (p<0.001). CTSB was elevated in active mouse whole brains (p<0.005) but not in retinas, gastrocnemius muscles, or serum. No dosing effect was observed. Retinal BDNF was not elevated with exercise.
Our results show that increased exercise intensity does not provide increased functional protection from LIRD. Interestingly, high+LIRD mice did not show significant benefit. Together this suggests that forced exercise’s influence on the retina is sufficient at a low threshold. The molecular basis for this protection is still unclear. It may be that low intensity exercise is sufficient to protect against retinal degeneration, a finding that may have implications for use of exercise as a therapeutic approach in treatment of vision loss.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
This PDF is available to Subscribers Only