Photoperiod affects oxidative stress in the liver of Cricetulus barabensis through the Nrf2-Keap1 signaling pathway

Changes in photoperiod affect both oxidative stress (OS) levels and antioxidant enzyme activities in animals. The liver accounts for a vital body metabolic organ. Different light durations may produce different outcomes in terms of OS and liver antioxidant pathways, but the underlying mechanism is not yet understood. This study investigated the effects of diverse photoperiods (SD, short day; MD, moderate day; LD, long day) on OS degree (H2O2 and MDA), antioxidant enzyme activities (superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GPx]), liver total antioxidant capacity, and the Nrf2-Keap1 signaling pathway in striped dwarf hamsters (Cricetulus barabensis) livers. Our results showed that (1) SD treatment for 8 weeks increased the levels of phosphorylated Nrf2, upregulated the Nrf2-Keap1 signaling pathway, and increased the protein expression of SOD and GPx, while decreasing the MDA concentration, all of which reduced the OS degree. (2) Additionally, LD treatment for 8 weeks reduced the extent of Nrf2 phosphorylation, resulting in downregulation of the Nrf2-Keap1 pathway, thus reducing protein expression of SOD2 and CAT, increasing the concentrations of H2O2 and MDA, and increasing OS degree. Collectively, OS levels in C. barabensis liver decreased during SD but increased during LD.