Ubiquitous overexpression of CuZn superoxide dismutase does not extend life span in mice

Oxidative damage has been implicated in the aging process and in a number of degenerative diseases. To investigate the role of oxygen radicals in the aging process in mammals, the life spans of transgenic mice on a CD-1 background expressing increased levels of CuZn superoxide dismutase (CuZnSOD), the enzyme that metabolizes superoxide radicals, were determined. Homozygous transgenic mice with a two- to five-fold elevation of CuZnSOD in various tissues showed a slight reduction of life span, whereas hemizygous mice with a 15- to 3-fold increase of CuZnSOD showed no difference in life span from that of the nontransgenic littermate controls. The results suggest that constitutive and ubiquitous overexpression of CuZnSOD alone is not sufficient to extend the life spans of transgenic mice.