Effects of GABA, glycine, and sodium barbiturate on dendritic growth in vitro.

Dendritic growth and dendritic arborization of both the large neurons of the cerebral and the cerebellar cortex and the small bipolar neurons were studied in vitro under normal feeding conditions and under the influence of GABA, glycine, and sodium barbiturate. By the end of week 1 the neurons cultured in normal nutrient developed primary dendritic shafts, demonstrating a tendency for bifurcation. By the end of week 2 the neurons appeared as numerous secondary dendritic branches studded with spines. The dendritic development and growth proceeded continuously until week 12 when no further growth and differentiation of the dendritic arborization was noted. Feeding medium enriched with GABA or glycine enhanced dendritic growth and dendritic arborization in vitro. On the contrary, feeding medium contained sodium barbiturate, partially suppressed dendritic growth and dendritic arborization in the neurons of the cerebral and the cerebellar explants. Ultrastructural studies revealed that sodium barbiturate partially suppressed the synapse formation between the neuronal circuits of the cortical explants.