Composition and Metabolism of Gangliosides in Rat Peripheral Nervous System During Development

Abstract: Ganglioside composition of rat trigeminal nerve was studied during development in order to understand the changes that occur as a result of cellular differentiation in the nerve. The ganglioside composition of the trigeminal nerve was entirely different from that of brain. The major gangliosides in adult trigeminal nerve were GM₃, GD₃, and LM₁ (sialosyl-lactoneotetraosylceramide or sialosylparagloboside). The structure of LM₁ and other gangliosides was established by enzymatic degradation and by analysis of the products of acid hydrolysis. At 2 days after birth, when the Schwann cells were immature, GM₃ and GD₃ were the major gangliosides in the nerve, 50 and 18 mol %, respectively. As the nerve developed and Schwann cells proliferated and myelinated the axons, the mol % of GM₃ and GD₃ reduced and that of LM₁ steadily increased. Polysialogangliosides did not change drastically with nerve development. The rate of deposition of LM₁ in the nerve with age was very similar to that of myelin marker lipids, cerebrosides, and sulfatides; thus, deposition appears to be localized mainly in the rat nerve myelin. LM₁ also had long-chain fatty acids 22:0 and 24:0, which are not usually found in CNS gangliosides. The ganglioside pattern of the rat trigeminal nerve was very similar to that of rat sciatic nerve, but was different from that of rabbit and chicken sciatic nerve. The activity of the two key enzymes involved in the metabolism of GM₃, viz., CMP-N-acetylneuraminic acid:lactosylceramide sialyltransferase and UDP-N-acetylgalactosamine:GM₃-N-acetylgalactosaminyltransferase, was also studied during development of the nerve and brain. The developmental profiles of both enzymes were consistent with the amounts of GM₃ present in the nerve.