Optic nerve integrity is required for light to affect retina ganglion cell gangliosides

The labeling of retina ganglion cell and optic tectum gangliosides after an intraocular injection ofN-³H]acetylmannosamine (³H]ManNAc) is higher in chickens exposed to light than in those maintained in darkness (1,2). In the present work we studied whether the signal for the higher labeling of ganglion cells in light originates in the photoreceptor layer or comes from the nerve terminal. For this purpose the labeling of ganglion cell gangliosides was determined in light and dark in chickens with one optic nerve severed. The results showed that the effect of light occurred only in the eye normally connected to the optic tectum. In the eye with its optic nerve severed, no difference was observed between the labeling of gangliosides in animals in light and dark, having both groups the labeling values of the normal eyes exposed to light. The results indicate that the information that decreases labeling in darkness or accelerates it in light originates in the nerve terminal.Special Issue dedicated to Prof. Edwardo De Robertis.