Response to hyperoxia is associated with similar ho-1 gene expression level in lungs of aging CBA mice of both sexes

• In steady state conditions HO-1 and HO-2 isoforms are affected by age and sex only on protein level.
• Ho-1 gene expression Is induced upon hyperoxia in all age groups, contrary to ho-2 which was lowered solely in 12 months old males.
• Higher HO activity in control aged females compared to their youngest counterparts demonstrates better protection against oxidative stress of old females per se.
• Sex-related response to oxidative stress may be mediated via regulation and interaction of HO.

Beside classical antioxidative enzymes, the response to hyperoxia might be mediated via regulation of other systems, such as heme oxygenase (HO). Ho-1 gene expression is found to be upregulated by hyperoxia in all groups of mice, while HO-1 protein isoform was increased only in 4 months old male mice. In steady-state conditions ho-1 and ho-2 gene expression remained unchanged irrespective of sex or age, which was not the case with protein level of both isoforms. This study suggests that in lungs of CBA mice the response to oxidative stress may be mediated through the interaction of other systems such as heme oxygenase, primarily via upregulation of ho-1 gene expression in both sexes. Contrary to our previous study in liver of hyperoxia treated mice, current results might imply that at conventional oxygen conditions lungs of female mice with the emphasis on aging females, are better prepared for oxidative stress conditions through the increase of HO-activity.