Ganglioside Profiles during Neural Tissue Development

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Abstract
The accumulation and species distribution of gangliosides in cultured cerebral cells and in the late prenatal stage of the developing rat brain were examined as a function of their growth state. The concentration of lipid-bound sialic acid in cerebral cells rises from a value of about 5 nmol/mg protein at day 1 to a peak level of 16.2 nmol/mg protein by 12 days, followed by a substantial decrease after 25 days in culture. When expressed per cell DNA, a linear increase of about 10-fold, notably after 10 days in culture, in the amount of sialic acid is seen. The most significant change in the species distribution is an apparent accumulation of disialo ganglioside (GD1a), trisialo ganglioside (GT) and tetrasialo ganglioside (GQ), whereas a marked reduction of GD3 is evident. The accumulation of sialic acid and the developmental patterns of the ganglioside species in vitro reasonably agree with the developing prenatal brain. By birth, both GT and GQ account for about 36% of the total brain gangliosides as compared to 40% in the mature cerebral cultures. Since in the newborn rat brain synaptogenesis is not prominent, the increase in the ganglioside complexity could be associated with neuritic sprouting and establishment of nonsynaptic interneuronal connections. Rabbit antiserum raised against pure GD1a reacted preferentially with the neuronal cell bodies and neurite extensions as observed by an indirect immunofluorescence technique. A progressive increase in immunofluorescence labeling paralleled accumulation of polysialogangliosides and culture maturation. In this context, the dissociated cerebral cells provide a powerful tool for investigating aspects of neuronal development because of the possibility of correlating neurochemical data with ultrastructure and cell-surface-related events.