Changes in ganglioside composition of photoreceptors during postnatal maturation of the rat retina

To examine at which stage the unusual ganglioside composition observed inadult retinal photoreceptor cells was established, and to see whetherganglioside changes could be correlated to distinct maturational events,quantitative and qualitative variations in gangliosides within pure sheetsof photoreceptors during postnatal differentiation and aging of retina werestudied. Retinas were separated into their component layers, (particularlyphotoreceptor layers uncontaminated by other neuronal types) by exploitinga technique of mechanical separation by vibratome. We extracted lipids fromthe cell membranes and analyzed the ganglioside composition by highperformance thin layer chromatography. The data show that from the earliestrecordable postnatal age (6 days) until late in life (18 months),photoreceptors contain low quantities of lipid-bound N-acetyl neuraminicacid and a simplified ganglioside profile compared to inner retinalneurons. Specific ganglioside changes occur within photoreceptor cellsduring postnatal maturation and aging, with downregulation of a-pathway GM1and overlapping upregulation of b- pathway GD1b taking place during theperiod corresponding to outer segment formation, correlating with the onsetof retinal function.