Selected P2 purinoceptor modulators prevent glutamate-evoked cytotoxicity in cultured cerebellar granule neurons

Primary cultures of granule neurons derived from cerebella of postnatal rats are endowed with Glu receptors. Glu receptor agonists exert a trophic influence on differentiating granule cells but, with maturation, the cells become vulnerable to excitatory amino acids. Here we show that the P2 purinoceptor antagonist basilen blue abolishes in rat cerebellar granule neurons the cytotoxic action of glutamate with an IC50 in the 10-20 microM range. Within the same concentrations, basilen blue inhibits binding of [3H] ATP to cerebellar granule cells, glutamate-evoked release (but not uptake) of [3H] D-aspartate and Ca2+ uptake. Furthermore, the extracellular phosphorylation of a major 45-kDa endogenous ecto-protein substrate of cerebellar granule neurons is inhibited with an IC50 of about 1 microM. Similar effects are elicited by 5-adenylylimidodiphosphate, a P2 purinoceptor agonist, when supplied to the neurons for 8 days previously to the addition of glutamate. Our data point to the use of P2 purinoceptor modulators as novel elements for understanding and controlling glutamate-mediated excitatory neurotoxicity and neurotransmission. We suggest a possible involvement of P2 purinoceptors in these actions.