**5. Conclusions**

Topical administration of GLP-1 in an experimental model of DR (db/db mice) confers protection against the damage caused by nitro-oxidative stress. The GLP-1-mediated increase of some antioxidant enzymes such as MnSOD and CuZnSOD is an important contributing factor. The prevention of DNA/RNA damage, the increase in DNA repair and the enhancement of cellular proliferation observed after treating with GLP-1 all reinforce the concept that GLP-1 promotes neurogenesis in the diabetic retina. However, further studies not only to confirm this important issue, but also to unravel the underlying mechanisms linking the antioxidant effects and cellular proliferation are needed.

**Author Contributions:** Conceptualization, P.B., R.S. and C.H.; methodology, H.R., P.B., J.S. and C.H.; formal analysis, H.R., P.B., J.S., J.H., R.S. and C.H.; investigation, H.R., P.B., J.S., J.H., R.S. and C.H.; resources, R.S. and C.H.; data curation, H.R., P.B., R.S. and C.H.; writing—original draft preparation, H.R., P.B.; writing—review and editing, R.S. and C.H.; supervision, P.B., R.S. and C.H.; project administration, C.H.; funding acquisition, R.S. and C.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by grants from the Ministerio de Economía y Competitividad (DTS15/00151, PI16/00541, SAF2016-77784) and the Fundació La Marató TV3 (201629-10). The funders had no role in the design of the study; in the collection, analyses or the interpretation of the data; in the writing of the manuscript or in the decision to publish the results.

**Acknowledgments:** H.R. is the recipient of a gran<sup>t</sup> from the Ministerio de Economía y Competitividad (BES-2017-081690). J.S. is the recipient of a gran<sup>t</sup> from the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR). The histological processing was performed by ICTS "NANBIOSIS", more specifically by Unit 20 of CIBER in Bioengineering, Biomaterials & Nanomedicne (CIBER-BBN) at the Vall d'Hebron Research Institute.

**Conflicts of Interest:** The authors declare no conflict of interest.
