Complex Probiotics Supplementation Improves Overtraining-Induced Muscle Inflammatory Response and Antioxidant Status Via LPS-TLR4/NF-κb Signalling Pathway in Rats

Abstract Background: Prolonged endurance and intensive exercise has shown detrimental effects on muscle health as well as causes intestinal dysbiosis. Probiotics are known as live microorganisms effective in improving gut microbiota and immunity to warrant health and well-being, which exert global and local biological functions on gut and muscle comprising of anti-oxidative stress, anti-inflammatory and anti-apoptosis, etc,. This research was conducted to investigate whether complex probiotics supplementation could alleviate excessive exercise-induced muscle damage and underlying signaling mechanism in rats. Methods: Thirty-two male SD rats were randomly allocated to four groups: control (SC), exercise (EC), probiotics (SP) and exercise with probiotics (EP) (n = 8 each). In the overtraining model, rats were arranged to an incremental load training on the treadmill 6 days/week for 8 weeks and gavaged with complex-probiotic-preparation (4 × 10 9 CFU/g) containing maltodextrin or maltodextrin only once a day. Serum and soleus were collected at the end of experiment. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities, the levels of lipopolysaccharide (LPS), interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), and muscle total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), catalase (CAT) in soleus were measured. Furthermore, soleus protein expression of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), p-p65/p65, Bax, Bcl-2, caspase-9 and caspase-3 were determined by western blotting assay. Results: The findings indicated that excessive exercise induced a significant increased CK and LDH activities, LPS levels, relative protein expression of TLR4, MyD88, p-p65/p65, inflammatory cytokines and lipid peroxidation ( p < 0.05). Simultaneously, the antioxidant elements including T-AOC, GPx, CAT were markedly decreased in the muscle of EC group ( p < 0.05). In addition, up-regulated the protein expression of Bax/Bcl-2, cleaved caspase-9/procaspase-9 and cleaved caspase-3/procaspase-3 in muscle ( p < 0.05). Administration of complex probiotics attenuated overtraining-induced inflammatory response, oxidative injury and TLR4/nuclear factor-kappa B (NF-kB) signaling factors expression as a result of reversing the most of above altered biochemical parameters ( p < 0.05), and there was only tendency downregulation in the expression of apoptosis-regulated proteins ( p > 0.05). Conclusions: Administration of complex probiotics could improve capability of the anti-oxidant, anti-inflammatory status induced by excessive exercise in rat skeletal muscle possibly via protecting the gut mucosal barrier, inhibiting the outflow of endotoxin, attenuating the action of TLR4-mediated NF-kB pathway.