Reversal photoisomerization of all-trans retinal in primary cultures of chicken retinal ganglion cells

DIÁZ N M; MORERA L.P.; GUIDO ME.

Córdoba

Congreso; XXVIII CONGRESO ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN NEUROCIENCIAS; 2013

SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN NEUROCIENCIAS

We previously reported light responses in GUCY1* (blind) birds mediated by the inner retina and the presence of intrinsically photosensitive retinal ganglion cells expressing the photopigment melanopsin in the retina of wt chickens. Bistable photopigments responsible for photosensitivity may use a different visual cycle in the inner retina for chromophore regeneration that relies upon distinct isomerase activities. In the present study, we investigated the expression and activity of different visual cycle enzymes and levels of retinal chromophores (11-cis RAL and all-trans RAL) in the inner retina of wt birds. Levels of 11-cis RAL were higher in the ganglion cell (GCL) and inner nuclear (INL) layers from light-adapted birds as compared with those in the dark with higher levels of all-trans RAL in this condition. Also, the photoisomerase RGR was expressed in the GCL which colocalized with Muller cell markers whereas different retinol deshydrogenases were seen in the retina and Muller cell cultures. Isomerase activity was only found in the INL while acyl CoA:retinol acyltransferase (ARAT) was observed in both INL and GCL. These results suggest that a novel visual cycle takes place in the chicken inner retina to support retinoid isomerization in non-visual photosensitive cells.