Exogenous administration of coenzyme Q10 restores mitochondrial oxygen consumption in the aged mouse brain

• Age-dependent changes in mitochondrial function and CoQ content were studied in mice. • Mitochondrial oxygen consumption reduced in the brains of aged male mice. • This decrease in oxygen consumption was accompanied by no change in CoQ content. • Oral administration of CoQ improved oxygen consumption in aged mouse brain. The level of coenzyme Q (CoQ) has been shown to decrease in an age-dependent manner in several types of animals. However, whether CoQ-dependent mitochondrial function decreases with aging remains unclear. In this study, we found that mitochondrial complexes I and II exhibited significantly reduced oxygen consumption in the brains of aged male mice relative to young male mice, although this decrease in oxygen consumption was not accompanied by a change in the CoQ 9 or CoQ 10 content. Nevertheless, the administration of exogenous CoQ 10 significantly increased the content of CoQ 10 and CoQ 9 in the brain mitochondria of aged male mice and restored complex I- and II-mediated oxygen consumption to levels comparable to those observed in young mice. These results indicate that mitochondrial oxygen consumption in the brain decreases in aged male mice. Furthermore, these results suggest that exogenous CoQ 10 restores mitochondrial oxygen use to levels equivalent to those observed in young mice.