Daily rhythm of gene expression in rat superoxide dismutases

Antioxidant enzymes are a mainstay of the defense system of any organism to fight oxidative stress caused by physiological and non-physiological production of free radicals. The oxidative status of the tissues is known to regulate these enzymes, together with other factors such as hormones and cytokines. In the present work, we show the daily rhythmicity in the expression of genes for copper-zinc and manganese superoxide dismutases (Cu-Zn and Mn SODs) as observed in several tissues of normal male rats. Intestine, lung, and cerebellum showed significant daily variations. Liver, brain cortex, and mesencephalon also have daily changes although statistically not significant. A possible relation with the oxidative status and the metabolic activity of the organism is discussed.