Labelling of retina and optic tecta glycoproteins of chickens in light and dark after intraocular injection of N-[3H]acetylmannosamine

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 of N-[3H]acetylmannosamine ([3H]ManNAc) is higher in chickens exposed to light than in those maintained in darkness. 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.

The effect of light exposure following an intraocular injection of [3H]N-acetylmannosamine on the labeling of gangliosides and glycoproteins of retina ganglion cells and optic tectum of singly caged chickens

Ten-day-old chickens that after a 2-day-period of adaptation to dark received an intraocular injection of [3H]N-acetylamannosamine ([3H]ManNAc) and were exposed, individually housed, to light, have more labeling in the gangliosides and glycoproteins of the ganglion cell layer of retina and in the contralateral optic tectum compared to their counterparts that remained in darkness. No differences were found in the labeling of the acid soluble fraction of the ganglion cell layer between the animals in dark and light at 0.5 and 5 h after the injection of [3H]ManNAc. No differences could be observed in the quality or storage of the gangliosides labeled in light with respect to those labeled in dark, but those labeled in light had a higher percent of labeling released by neuraminidase at 5 h after the intraocular injection of the labelled precursor. In animals exposed to intermittent light, the increased labeling with respect to dark was smaller than that found in animals exposed continuously to light.