Changes with age in copper and superoxide dismutase levels in brains of C57BL/6J mice.

Superoxide dismutase activity in brains of male C57BL/6J mice decreased with age by 36% on a protein base and by 32% on a DNA base between 50 and 900 days of age. Brain copper increased by 45% up to 600 days of age and appeared to increase slightly from 600 to 900 days of age. Feeding of copper gluconate (5 x 10(-3)M) failed to change the level of copper in either young or old brain, and superoxide dismutase activity was not significantly increased or inhibited by copper feeding. Cupric chloride (2.35 x 10(-6)M) was found to inhibit purified superoxide dismutase (2 x 10(-8)M) by 50%. These observations indicate that brain copper concentrations do not directly determine the activity levels of the copper containing enzyme, superoxide dismutase, under normal ageing conditions.