THE STUDY OF THE MECHANISMS OF THE TOXIC EFFECT OF OUABAIN ON THE CULTURE OF RAT CEREBELLAR CELLS

Both endogenous and exogenous cardiotonic steroids (CTS), specific inhibitors of Na,K-ATPase, can evoke different physiological responses in the central nervous system by influencing synaptic transmission and intracellular signal cascades. In addition, they might participate in the development of neurodegenerative processes in the central nervous system. The toxicity of CTS for neurons has been shown earlier, but it has not been sufficiently char-acterized, and the mechanism of neuronal death has not been described in detail. In the present study it was shown that the viability of the primary cell culture of rat cerebellum under the action of 10 μM ouabain already decreases at 12 h of incubation and does not further decrease after 24 and 48 h of incubation, which suggests that this is a fast process, presumably apoptotic. At 12 h of incubation, the action of both toxic (10 μM) and nontoxic (1 μM) concentrations of ouabain leads to a shift in the ratio of apoptosis regulating proteins of the Bcl-2 family towards proapoptotic ones. At the same time, reducing the time of incubation of cells with 10 μM ouabain, but not with 1 μM ouabain, to 3 hours also leads to a decrease in the ratios of antiapoptotic proteins Bcl-2 and Bcl-xL to proapoptotic Bax and Bak, respectively, which indicates a fast development of apoptotic processes in response to ouabain neurotoxicity. Thus, it can be assumed that the effect of toxic concentrations of ouabain which cause neuronal death, is carried out through the mechanism of the mitochondrial apoptotic pathway.