Cation channel control of neurite morphology

The development of neuronal polarity and morphology is essential for a func tioning nervous system. The present study was undertaken to explore whether blockade of specific channels alter neuronal morphology. Retinal ganglion cells were cultured in the presence of antagonists to NMDA, AMPA/kainate, L -, N-, P-, and Q-type voltage-dependent calcium channels (VDCCs). Five para meters were measured under these conditions: the number of neurites at the cell body, total neurite length, the length of the longest neurite, the num ber of branch points per neurite, and the diameter of the cell soma. Antago nists to NMDA and L-type VDCCs reduce the number of neurites at the cell bo dy; antagonists to P- and Q-type VDCCs increase the number of neurites. Ant agonists to the N-type VDCCs increase total neurite outgrowth, while antago nists to the NMDA and P-type channels reduce total neurite length. Antagoni sts to the NMDA and L-type channels increase the length of a single neurite , while decreasing the number of branch points; antagonists to the P- and Q -type VDCCs do essentially the opposite-increase the number of neurites, wh ile decreasing the length of each. Blockade of one or more cation channels in developing retinal ganglion cells significantly perturbs neurite morphol ogy. This study may help elucidate part of the role that cation channel sig naling plays in neuritic development. (C) 1999 Elsevier Science B.V. All ri ghts reserved.