The excitatory amino acid glutamate has been shown to be toxic
to a
number of neuronal cell types both in
vitro and in vivo. It has also been shown to be capable of controlling
the
development of neurons grown
in vitro. Using time-lapse video microscopy techniques the effects of
glutamate on the rate of neurite
outgrowth and growth cone motility were examined on cultured mouse spinal
cord neurons. Concentrations
in the range of 1 to 100 µM caused a significant inhibition of neurite
outgrowth
and concentrations of 10
and 100 µM significantly inhibited growth cone activity. In addition
it was
shown that the kainate/AMPA
receptor antagonist (±)3-(2-carbvoxypiperazin-4-yl)-propyl-l-phosphonic
acid,
but not the NMDA receptor
antagonist 6,7-dinitroquinoxaline-2,3-dione, was capable of blocking the
inhibitory actions of glutamate on
both outgrowth and motility. These results show that, at least in the culture
system employed, glutamate
might have a role in regulating neuronal development and function.