Pro-apoptotic effect of methylguanidine on hydrogen peroxide-treated rat glioma cell line

Guanidino compounds, as methylguanidine (MG), may play an important role in the etiology of neurological complications which occur in uremic syndrome. Dementia is a neurological complication more common in uremic patients than in general population and several types of dementia are associated to astroglial apoptosis. Here we report the effect of MG on oxidative stress-induced apoptosis in rat glioma cell line (C6) in vitro. The oxidative stress was induced by hydrogen peroxide (H(2)O(2); 1 mM) and the cellular and molecular parameters were observed after 18 h. Uremic conditions were simulated by pre-incubation of C6 cells with MG (0.1-10 mM) 1h before H(2)O(2)-induced oxidative stress. MG alone did not affect cell viability, but it significantly increased cell death induced by H(2)O(2), as assessed by MTT assay. This effect could be related to the MG capability to enhance H(2)O(2) pro-apoptotic effect on C6 cells. The fluorescent dye FURA 2-AM test showed a significant raise in [Ca(2+)](i) in MG and H(2)O(2) co-treated C6 cells, mainly for depolarizing mitochondrial membrane potential. Furthermore, MG in a concentration-dependent manner, significantly increased H(2)O(2)-induced Bax expression, activation of caspase-3 and PARP in C6 cells. This study firstly reports that the uremic catabolyte MG could contribute to neurodegeneration associated to uremia enhancing the pro-apoptotic effect of H(2)O(2) and through an alteration in mitochondrial calcium homeostasis in glial cells.