C-phycocyanin protects cerebellar granule cells from low potassium/serum deprivation-induced apoptosis

We tested the potential cytoprotective role of C-phycocyanin in rat cerebel lar granule cell cultures. Cell death was induced by potassium and serum (K /S) withdrawal. Cell viability was studied using the neutral red assay and laser scanning cytometry with propidium iodide as fluorochrome. C-phycocyanin (1-3 mg/ml) showed a neuroprotective effect against 24 h of K /S deprivation in cerebellar granule cells. After 4 h K/S deprivation this compound 3 mg/ml) inhibited formation of reactive oxygen species, measured as 2',7'-dichlorofluorescein fluorescence, showing its scavenger capability . Pre-treatment with C-phycocyanin reduced thymidine incorporation into DNA below control values and reduced dramatically apoptotic bodies as visualiz ed by propidium iodide, indicating inhibition of apoptosis induced by K/S d eprivation. Flow cytometry studies, using propidium iodide in TritonX 100 permeabilized cells, indicated that 24 h K/S deprivation acts as a proliferative signal for cerebellar granule cells, which show an increase in S-phase percentage and cells progressed into the apoptotic pathway. C-phycocyanin protected ce rebellar granule cells from the apoptosis induced by deprivation. These res ults suggest that C-phycocyanin prevents apoptosis in cerebellar granule ce lls probably through the antioxidant activity. It is proposed that K/S depr ivation-induced apoptosis could be due, in part, to an alteration in the ce ll cycle mediated by an oxidative stress mechanism.