Inhibition of phosphatidylcholine synthesis is associated with excitotoxic cell death in cerebellar granule cell cultures.

Abstract

Glucose deprivation (GD) enhances the sensitivity of cerebellar granule cells to die by excitotoxicity. Neither 70 min of GD, a treatment that depletes cell energy resources, nor exposure to 20 microM glutamate (GLU) for 30 min, induce significant cell death in cultures of cerebellar granule cells. However, the combined treatment with GLU and GD induces choline (Cho) release before excitotoxic cell death. We investigated whether the neurotoxic effect of this treatment is related with inhibition of phosphatidylcholine (PC) synthesis. We found that exposure to GLU for 30 min, to GD for 70 min, and to the combination of both, inhibited PC synthesis at the end of treatment by 71%, 92% and 91%, respectively. The inhibition of PC synthesis was accompanied by a decrease in the incorporation of [(3)H]Cho into phosphocholine and by an increase of the intracellular content of free [(3)H]Cho, indicating that these treatments inhibit the synthesis of PC by inhibiting choline kinase activity. However, only the combined treatment with GLU and GD induced a prolonged inhibition of PC synthesis that extended after the end of treatment. These results show that excitotoxic death is associated with sustained inhibition of PC synthesis and suggest that this effect of the combined treatment with GLU and GD on PC synthesis is produced by an action on an enzymatic step downstream of choline kinase activity.