CHANGES IN GLUR4 EXPRESSION INDUCED BY METABOTROPIC RECEPTOR ACTIVATION IN RADIAL GLIA CULTURES

The expression of neurotransmitter receptors in glial cells has sugges ted a regulatory role of these cells in synaptic function, In radial g lia, glutamate receptors elicit a cascade from the membrane to the nuc leus and a consequent change in gene expression. In order to gain insi ght into this process, we address the question of whether receptor act ivation leads to changes in the repertoire of AMPA/KA glutamate recept or subunits in Bergmann and Muller glial cells. Of the subunits invest igated, only GluR4 was up-regulated in Bergmann glial cells both at mR NA and protein levels. In contrast, in Muller glial cells Glu treatmen t leads to a reduction in GluR4 mRNA and protein expression. Both effe cts are receptor-mediated and must probably involve group I of metabot ropic glutamate receptors. Accordingly, using Northern blot analysis a nd RT-PCR we detected the expression of both mGluR1 and mGluR5 transcr ipts in the cultured cells. Our results confirm that glutamate recepto rs in Bergmann and Muller cells modulate gene expression and further s trengthen a plausible role of glial cells in long-lasting changes in t he central nervous system. (C) 1998 Elsevier Science B.V, All rights r eserved.