NMDA TREATMENT AND K-INDUCED DEPOLARIZATION SELECTIVELY PROMOTE THE EXPRESSION OF AN NMDA-PREFERRING CLASS OF THE IONOTROPIC GLUTAMATE RECEPTORS IN CEREBELLAR GRANULE NEURONS()
R. Balazs et al., NMDA TREATMENT AND K-INDUCED DEPOLARIZATION SELECTIVELY PROMOTE THE EXPRESSION OF AN NMDA-PREFERRING CLASS OF THE IONOTROPIC GLUTAMATE RECEPTORS IN CEREBELLAR GRANULE NEURONS(), Neuroscience letters, 137(1), 1992, pp. 109-113
Growth conditions which promote the survival of cerebellar granule cel
ls in culture, such as high K+ or N-methyl-D-aspartate (NMDA) treatmen
t, also promote the functional expression of an NMDA-preferring subtyp
e alone of the ionotropic glutamate receptors. The selective regulatio
n of NMDA receptors detected electrophysiologically in individual cell
s, using the whole cell patch clamp technique, is characteristic of gr
anule cells in general: NMDA-induced Ca-45(2+) influx increased severa
l-fold in cultures treated with either high K+ or NMDA. The increase i
n NMDA receptor activity was correlated with an increase in the expres
sion of an NMDA receptor protein. Since the effect of these 'trophic'
conditions is mediated through Ca2+, the induced increase in the densi
ty of NMDA receptors (which gate a Ca2+ conductance) provides a positi
ve feedback for strengthening the trophic influences.