Glutamate treatment and preconditioning differently affect cathepsin B release and intracellular proteases in primary cultures of cerebellar granular cells

Abstract

Effects of serum deprivation, preconditioning to serum deprivation, and of glutamate toxicity on cathepsin B (CB) release and intracellular activities of CB, caspase-3 and calpain were studied in primary cerebellar granular cell cultures. The cells release CB when they are deprived of trophic factors or treated with glutamate, and this secretion is not accompanied by cell death. Similar CB secretion can be detected in organotypic cultures of hippocampal slices. Preconditioning reduces CB release in cerebellar cultures and modulates effects of glutamate on intracellular proteolytic activities. Glutamate augments the ratio of CB activity in the cultural medium and within cells, while preconditioning results in a decrease of this ratio. We suggest that extracellular CB is a potential player in mechanisms of neuronal cell preconditioning.