Investigation the Effects and Mechanisms of Autolytic Active Peptides from Shrimp Head on Anti-fatigue in Mice Based on the Keap1/Nrf2/ARE Signaling Pathway

To investigate the influence of shrimp head autolytic active peptides (SAP) on the anti-fatigue ability of mice, low, middle, and high doses of SAP were administered orally to mice for 28 d. Subsequently, load-bearing swimming time, malondialdehyde content in liver tissue, blood lactic acid content, blood urea nitrogen content, lactate dehydrogenase activity, reduced glutathione content, liver/muscle glycogen content, and mRNA expression of Keap1, Nrf2, HO-1, and NQO-1 were measured and the liver tissue morphology of each group of mice was also observed. The results showed that compared with the normal control group (NC), the load-bearing swimming time of mice in each dose group of SAP was significantly prolonged (P<0.05), while the high-dose group of SAP (600 mg/kg·d) exhibited significantly decreased levels of malondialdehyde, blood lactic acid, and blood urea nitrogen (P<0.05), significantly increased levels of lactate dehydrogenase, reduced glutathione, and liver glycogen (P<0.05), significantly upregulated mRNA expression of Nrf2, HO-1, and NQO-1 (P<0.05), and significantly downregulated mRNA expression of Keap1 (P<0.05). The anti-fatigue effect was comparable to that of taurine positive control group (TP). In addition, by observing the tissue morphology of liver slices in each group of mice, each dose group of SAP showed similar morphology to the normal blank group, indicating that short-term continuous intake of appropriate amounts of SAP does could not affect the normal metabolic function of the mice liver and not cause damage to its liver. The results indicated that shrimp head SAP can activate the Keap1/Nrf2/ARE signaling pathway in mice, alleviate oxidative stress, protect cells from damage, and regulate energy metabolism, thus alleviating fatigue symptoms and exhibiting significant anti-fatigue effects.