Abstract
Purpose :
Taurine plays an important role in the survival of retinal neurons because its depletion causes retinal ganglion cell (RGC) and cone loss (Hadj-Saïd et al., IOVS 2016; 57:4692-4703) that may be greater after light exposure (ALE). Here we study the effects of acute light exposure on RGCs, melanopsin+RGCs (m+) and cones in an animal model of induced taurine depletion.
Methods :
Adult female albino Sprague Dawley rats (2 months old; n=16) were used for this study. β-alanine was administered in the drinking water to induce taurine depletion. One month later half of the animals were exposed to light (3000 lux) for 48 hours following previously described methods (García-Ayuso et al., Mol Vis 2011; 17:1716-1733). Light exposed and non-exposed animals were processed after two months of β-alanine treatment. Control animals had normal drinking water (non-treated). Whole-mounted retinas were incubated with antibodies against L- and S-opsin, Brn3a and melanopsin. The total numbers of L- and S-opsin+cones, Brn3a+ and m+RGCs were automatically quantified following previously described methods (García-Ayuso et al., IOVS 2015; 56:4592-4604; García-Ayuso et al., IOVS 2013; 54: 5888-5900).
Results :
In non-treated animals, one month ALE there was a significant decrease of 13% and 15% in the mean numbers of L- and S- cones, respectively, compared to control non-exposed animals, however light exposure did not affect the numbers of Brn3a+ or m+RGCs. β-alanine treatment resulted in a significant reduction in plasma taurine levels and significant reductions of all the studied populations, interestingly S-cones and m+RGCs populations were more severely affected. In treated animals, one month ALE there was a significant decrease in the mean numbers of cones compared to non-exposed animals that was similar to that observed for non-treated animals, while Brn3a+ and m+RGCs populations were not affected by light exposure. Besides, there was a significant decrease of 21% and 32% in the mean numbers of L- and S- cones, respectively, compared to control non-exposed animals.
Conclusions :
This study confirms that taurine depletion causes RGCs and cone loss, it shows, for the first time, that m+RGC are also sensitive to taurine depletion. These data further support the need for taurine in RGC and cone survival.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.