Circadian Rhythms of Antioxidant Enzyme’s Activity in Young and Adult Rats under Light Deprivation Conditions

Resumo

We have studied the age-related features of circadian rhythms of superoxide dismutase (SOD) and catalase activity in the liver of rats under conditions of light deprivation. In standard light conditions (LD), significant daily fluctuations in SOD activity with a maximum at 7:00 a.m. were detected only in young animals (1.5 months) while catalase activity was observed in both young animals (1.5 months) and adults (7.5 months) with peak at 4:00 a.m. The daily dynamics of total and specific activity of SOD and catalase in the liver of young and adult rats differed, depending on the period of ontogeny in which the impact of light deprivation had begun. When females after giving birth and their offspring were moved to darkness (group LD/DD), the circadian rhythms of SOD and catalase activities were found in the young rats and were absent in adult rats. However, circadian rhythms of the antioxidant enzymes (AOE) activities were inherent only in adult rats when light deprivation impacted on pregnant females (group DD/DD). Changes in circadian rhythms under light deprivation were characterized either by a phase shift of the enzymes activity (in LD/DD group) or by a violation of their development in ontogeny (in DD/DD group). With aging a significant decrease of catalase activity was compensated by an increase in the amplitude of circadian rhythms of this enzyme activity in animals of all groups. The presence of an ultradian rhythm in the general circadian cycle characterized by a second peak with a smaller amplitude and shorter period can be considered a distinctive feature of daily fluctuations in AOЕ activity in young rats in LD and LD/DD groups.