M. Monzón-Mayor, M. 1 , Santos Gutierrez, E. 2 , Romero-Alemán, M. d. M. 1 & Yanes , C. 2
1 Facultad Ciencias de la Salud. Universidad de Las Palmas, Gran Canaria.
2 Facultad de Biología, Universidad de La Laguna, Tenerife
Significant regeneration of retinal ganglion cell axons occurs after optic nerve transection through a permissive glial scar in Gallotia galloti. Although several of the cellular and molecular events underlying this process have been studied by our group, the functionality of the system has not been tested until now. The pupillary light reflex, accommodation and head orienting have been also used in other reptiles to test visual function (Dunlop et al., 2004). We examined 18 lizards at 3, 6, 9 and 12 months after transection. Our results revealed a tendency of eyelid closing within the first months after operation. Interestingly, by 6 months we detected a significant recovery of pupillary light reflex in two thirds of specimens including a robust response in 17 of them. However, visually guided behaviour recovery was observed only in 2 specimens, yet when presenting a prey (mealworm) in the right, affected eye, most lizards (89%) did not constrict the pupil to focus nor did they follow it as it moved, a behaviour which was detected in the unlesioned side. We conclude that a partial recovery of the visual pathway functionality takes place spontaneously in adult G. galloti, which could be enhanced by training or pharmacologically.
This work was supported by the Spanish Ministry of Education (Research Project BFU2007-67139, Regional Canary Island Government (ACIISI, Research Projects SolSub200801000281 and ULPAPD-08/012-4).