The chemokine growth-related gene product b protects rat cerebellar granule cells from apoptotic cell death through a-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate receptors

Cultured cerebellar granule neurons are widely used as a cellular model to study mechanisms of neuronal cell death because they undergo programmed cell death when switched from a culture medium containing 25 mM to one containing 5 mM K(+). We have found that the growth-related gene product beta (CROP) partially prevents the K(+)-depletion-induced cell death, and that the neuroprotective action of GRO beta on granule cells is mediated through the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) type of ionotropic glutamate receptors, GRO beta-induced survival was suppressed by 6-cyano-7-nitroquinoxaline-2,3-dione, which is a specific antagonist of AMPA/kainate receptors; it was not affected by the inhibitor of N-methyl-D-aspartate receptors, 2-amino5-phosphonopentanoic acid, and was comparable to the survival of granule cells induced by AMPA (10 mu M) treatment. Moreover, GRO beta-induced neuroprotection was abolished when granule cells were treated with antisense oligonucleotides specific for the AMPA receptor subunits, which significantly reduced receptor expression, as verified by Western blot analysis with subunit-specific antibodies and by granule cell electrophysiological sensitivity to AMPA. Our data demonstrate that GRO beta is neurotrophic for cerebellar granule cells, and that this activity depends on AMPA receptors.