Characteristics of gangliosides including O-acetylated species in growth cone membranes at several developmental stages in rat forebrain.

Growth cones, the motile tips of extending neuronal processes, are involved in accurate synaptogenesis. To study the developmental changes in ganglioside composition including O-acetylated gangliosides in growth cones, we analyzed the gangliosides in growth cone membranes (GCM) prepared from rat forebrains at different developmental stages. At several stages, GCM contained significantly larger amounts of gangliosides than the other membrane subfractions. The ganglioside content of GCM increased in amount with development. Moreover, in GCM, the relative amount of GD3 gradually decreased, and that of GD1a dramatically increased. There were significant differences in the composition of ganglioside species between GCM and the perinuclear plasma membrane subfraction (NM); most importantly, GCM had a higher ratio of GD1a to GM3 plus GD3 than NM. There were three different O-acetylated gangliosides in GCM: O-acetyl-GD3, O-acetyl-GT1b, and O-acetyl-GQ1b. The molar ratio of O-acetyl-GD3 decreased in GCM at later stages (5% of the total gangliosides at embryonic day 17, to 1% at postnatal day 5). However, those of the other two O-acetylated gangliosides were almost constant (1-2% of the total). Our results show that there are significant differences in ganglioside content and composition between the membrane subfraction of growth cones and the perinuclear portion. This suggests that several species of gangliosides, including O-acetyl-GD3, play a role in growth cone function.