The role of calcium signaling in early axonal and dendritic morphogenesis of rat cerebral cortex neurons under non-stimulated growth conditions

Ramakers, G. J. A., Avci, B., Van Hulten, P., Van Ooyen, A., Van Pelt, J., Pool, C. W., and Lequin, M. B. (2001). Dev. Brain Res. 126: 163-172. [Full text: PDF]

Abstract

The effects of depolarizing stimuli on neurite outgrowth have been shown to depend on an influx of extracellular calcium. However, the role of calcium under non-stimulated growth conditions is less well established. Here we investigated the contribution of calcium signaling to early morphogenesis of rat cerebral cortex neurons at three levels: by blocking L-type voltage sensitive calcium channels, by depleting intracellular calcium, or by blocking myosin light chain kinase.

Detailed quantitative morphological analysis of neurons treated for one day revealed that depletion of intracellular calcium strongly decreased the density of filopodia, arrested axonal outgrowth, and strongly decreased dendritic branching. Preventing influx through L-type voltage sensitive calcium channels and blocking of myosin light chain kinase activity selectively decreased dendritic branching.

Our results support an essential role for basal intracellular calcium levels in axonal elongation. Furthermore, under non-stilumated conditions, calcium entry through L-type voltage sensitive calcium channels and myosin light chain kinase play an important role in dendritic branching.