Circadian rhythms of antioxidant enzymes activity, clock, and inflammation factors are disrupted in the prefrontal cortex of aged rats. Potential targets for therapeutic strategies for a healthy aging.

Abstract

Age impairs cognitive functions and antioxidant defenses, for example, by increasing oxidative stress and inflammation in the brain. However, so far, there is no report on the consequences of aging on temporal patterns of proteins and lipids oxidation, antioxidant enzymes activity, endogenous clock and proinflammatory cytokine, in the prefrontal cortex (PFC). Therefore, our objectives here were: 1) to investigate the endogenous nature of 24h-rhythms of lipoperoxidation, protein carbonyls levels, CAT and GPx activity, RORa, and TNFα, in the rat PFC, and 2) to study the consequences of aging on the circadian organization of those factors in the same brain area. To do that, 3- and 22-mo-old male Holtzman rats were maintained under constant darkness conditions during 15 days before reaching the corresponding age. PFC samples were isolated every 4 h, under dim-red light, during a 24h period. Our results revealed circadian patterns of antioxidant enzymes activity, oxidative stress, RORa and TNFα proteins levels, in the PFC of young rats. The circadian distribution of the rhythms’ phases suggests the existence of a reciprocal communication among the antioxidant defenses, the endogenous clock, and the inflammation, in the PFC. Noteworthy, such circadian organization disappears in the PFC of aged rats. An increased oxidative stress would make the redox environment to change into an oxidative status, which alters the endogenous clock activity and disrupts the circadian organization of, at least part, of the antioxidant defenses and the TNFα, in the PFC. These results might highlight novel chronobiological targets for the design of therapeutic strategies addressed to a healthy aging.