Protein synthesis in neural cells in culture: role of cell density and neurohumors

Abstract

Protein synthesis was studied in C-6 glial cells and neuroblastoma (NB) cells as a function of cell density and after differentiation with dibutyryl cyclic AMP and treatment with either norepinephrine (NE), dopamine or L-dopa. In both C-6 glial cells and NB cells, unincorporated 3H-leucine decreased, whereas incorporation of 3H-leucine into protein increased with increasing cell density, particularly at high cell densities. Exposure of C-6 glial cells to NE at various doses for 60 minutes stimulated the efficiency of 3H-leucine incorporation into protein. This effect was not seen with L-dopa or dopamine. In contrast to the glial cells, in neuroblastoma cells all three neurohumors caused a decrease in the incorporation of 3H-leucine into protein. The increase in protein synthesis by NE was also seen in DBcAMP-differentiated glial cells. These findings suggest that cellular activity as reflected by protein synthesis is cell density dependent. In addition, neurohumor substances may play a regulatory role in the cellular activity of glial cells.