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

To examine at which stage the unusual ganglioside composition observed in adult retinal photoreceptor cells was established, and to see whether ganglioside changes could be correlated to distinct maturational events, quantitative and qualitative variations in gangliosides within pure sheets of photoreceptors during postnatal differentiation and aging of retina were studied. Retinas were separated into their component layers, (particularly photoreceptor layers uncontaminated by other neuronal types) by exploiting a technique of mechanical separation by vibratome. We extracted lipids from the cell membranes and analyzed the ganglioside composition by high performance thin layer chromatography. The data show that from the earliest recordable postnatal age (6 days) until late in life (18 months), photoreceptors contain low quantities of lipid-bound N-acetyl neuraminic acid and a simplified ganglioside profile compared to inner retinal neurons. Specific ganglioside changes occur within photoreceptor cells during postnatal maturation and aging, with downregulation of a-pathway GM1 and overlapping upregulation of b-pathway GD1b taking place during the period corresponding to outer segment formation, correlating with the onset of retinal function.