Cycloheximide abolishes pertussis toxin-induced increase in glutamate release from cerebellar granule neurones.

Abstract Release of glutamate from cerebellar granule neurones was stimulated either by adding 50 mM K + to normal Krebs medium, or by adding 5 mM Ca 2+ to neurones continuously depolarised with 50 mM K + in the absence of Ca 2+ . Pre-incubation of neurones for 16 h with pertussis toxin (PTX) increased the stimulated glutamate release in both K + -stimulated and continuously depolarised neurones. Under both conditions, the PTX-induced increase in release was abolished by cycloheximide. In contrast, in the presence of cycloheximide, PTX still prevented the GABA B agonist (−)-baclofen from inhibiting glutamate release. These results suggest that G-protein ADP-ribosylation by PTX in cerebellar granule neurones may increase synthesis of a protein associated with the L-type calcium channel.