[From prion diseases to the problem of aging and death].

The brain tissue of aging mice shows a factor that stimulates the proliferation of cells of glial origin both in primarily trypsinized and inoculated cultures. This factor that is likely to be of peptide origin is characterized by pronounced accumulation dynamics with increasing age in mammals, by unusually high thermal stability and by its possible detection in the brain extracts by means of isoelectrofocusing rather than electrophoresis. The author proposes a concept under which the brain tissue of aging mammals, including human beings, accumulates the factor that is active in stimulating the proliferation of glial elements, thus resulting in impairment of neuronal trophism, which can in turn be a cause of their death and, in the long run, a cause of death of the brain and the whole body.