Abstract: Objective: To investigate the fatigue-alleviating effect of peptides from porcine blood (PPB). Methods: Totally 200 male Kunming mice were randomly divided into one control group and three test groups. The mice from the control group were administered intragastrically with distilled water, and the mice from three test groups were administered intragastrically with PPB at doses of 0.83, 1.70 g/kg and 3.33 g/kg for 30 consecutive days. At 30 min after the last administration, loaded swimming time and anti-hypoxia survival time of the mice were recorded. The fatigue indices including red blood cell number, hemoglobin content, hepatic glycogen, muscle glycogen, blood urea nitrogen (BUN), blood lactate of the mice were assayed. Then, 32 more male Kunming mice were divided into one control group and one test group. The control group and the test group were administered intragastrically with distilled water and PPB at the dose of 1.70 g/kg for 30 consecutive days, respectively. At 30 min after the last administration, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), nitric oxide synthase (NOS), lactate dehydrogenase (LDH), creatine kinase (CK), and the contents of malondialdehyde (MDA) and nitric oxide (NO) were measured. The skeletal and cardiac muscles were subjected to histopathological examination. Results: PPB could significantly prolong the loaded swimming time and anti-hypoxia survival time of the mice, and obviously increase the number of red blood cells and the contents of hemoglobin, hepatic glycogen and muscle glycogen as well as the activities of SOD and GSH-Px, decrease the activities of NOS, LDH and CK, and the contents of BUN, MDA, NO and LA. PPB had obvious protective function against exercise-induced damage of skeletal and cardiac muscles. Conclusion: PPB has obvious fatigue-alleviating effect at the optimal dose of 1.70 g/kg. Its anti-fatigue effect is correlated to enhanced antioxidant enzyme activities (resulting in the alleviation of skeletal and cardiac muscle damages caused by excess free radicals generated after endurance exercise for a long time), reduced occurrence of central fatigue following the production of excess NO as a result of lower activity of NOS and enhanced aerobic metabolism capacity in the body.

Key words: peptides from porcine blood, alleviating fatigue, mice