Aerobic Exercise Combined With Oyster Peptide Prevents Sarcopenia Formation By Improving NMJ Transmission Efficiency

Objective:To explore the intervention and interaction of aerobic exercise and Oyster peptide(OP)on the formation of sarcopenia,and from the perspective of neuromuscular junction(NMJ),based on Laminβ2-VDCCs-Bassoon and FoxO1-Atrogin-1 signaling pathways explore the biological mechanism of aerobic exercise combined with OP supplementation in the intervention of D-galactose-induced sarcopenia in aging rats,thereby clarifying the role of NMJ in the prevention of sarcopenia,and providing experimental evidence for the application of oyster peptide combined with aerobic exercise in the prevention and treatment of sarcopenia.Methods:12-week-old healthy SD rats were randomly divided into five groups:NC control(NC,n=10),sarcopenia control(SA,n=10),sarcopenia OP intervention(SOP,n=10),sarcopenia aerobic exercise intervention(SAE,n=10),sarcopenia+aerobic exercise+OP intervention(SAEOP,n=10).Exercise training was not performed in the NC group,while sarcopenia formation was induced by intraperitoneal administration of D-gal in the SA,SOP,SAE,and SAEOP groups,the SOP and SAEOP groups received OP solution at a dose of 1.0 g/kg body weight per morning;SAE,the SAEP group performed 60 min weight-bearing swimming training every afternoon,5 times/week;However,exercise training was not performed in the S A or SOP group for 8 weeks.The rotarod fatigue test was performed 3 days before sampling to determine the locomotor activity and muscle coordination of rats in each group.Gastrocnemius muscle cross-sectional area was calculated by HE method;RT-PCR method was used to detect the mRNA expression of FOXO1 a,Atrogin-1,Lamininβ2,VDCCs,Bassoon mRNA expressionin in gastrocnemius muscle.;Western-blot method was used to detect the protein expressi on FoxO1a,P-FoxO1a,Atrogin-1,Lamininβ 2 in gastrocnemius muscle.Results:(1)Compared with NC group,gastrocnemius muscle weight and SMI ratio in SA group decreased significantly(p=0.001,p=0.038);The gastrocnemius muscle weight and SMI in the SOP,SAE,and SAEOP groups were significantly higher than thoSAE in the SA group(p=0.003,p=0.031;p=0.001,p=0.001;p=0.001,p=0.001).The HE staining results showed that compared with NC group,the gastrocnemius muscle in S A group was disorderly arranged,muscle fibers were atrophic,and the nucleus had a trend of centralization;However,in the SOP,SAE,and SAEOP groups,muscle fibers were arranged neatly,with significant improvement in muscle fiber roundness and nuclear centricity.Compared with NC group,the cross-sectional area,total protein content,and rotational fatigue test scores of gastrocnemius muscle fibers in SA group were significantly decreased(p=0.01,p=0.022,p=0.01);Compared with the SA group,the cross-sectional area of muscle fibers in the SAEOP group was significantly increased(p=0.007),the total protein content of gastrocnemius muscle in the SAE and SAEOP groups was significantly increased(p=0.025,p=0.007),and the scores of the SOP,SAE,and SAEOP groups were significantly increased(p=0.021,p=0.006,p=0.003);Compared with the SAE group,the cross-sectional area,total protein content,and rotational fatigue test scsaores of muscle fibers in the SAEOP group showed a further upward trend,but there was no significant difference.(2)Compared with NC group,the expression of FoxO1a mRNA and p-FoxO1a/FoxO1a in SA group was significantly decreased(p=0.002,p=0.002),while the expression of Atrogin1 mRNA and protein was significantly increased(p=0.000,p=0.000);Compared with the SA group,the expression of FoxO1a mRNA and p-FoxO1a/FoxO1a in the SOP,SAE,and SAEOP groups were significantly increased(p=0.015,p=0.008,p=0.008;p=0.011,p=0.002,p=0.000),while the expression of Atrogin-1 mRNA and protein was significantly decreased(p=0.002,p=0.001,p=0.000;p=0.002,p=0.001,p=0.001).Compared with the SAE group,there was no significant difference in the expression of FoxOla mRNA and p-FoxOla/FoxO1a in the SAEOP group(p=0.947,p=0.556),while the expression of Atrogin-1 mRNA was significantly decrease(p=0.036).(3)Compared to the NC group,the SA group Laminin β2’s mRNA and protein expressions and VDCCs and Bassoon’re mRNA expressions were significantly decreased(p=0.002,p=0.000,p=0.013,p=0.000);Compared with SA group,Lamininβ2 in SOP,SAE,and SAEOP groups mRNA and protein expression and Bassoon mRNA expression were significantly increased(p=0.000,p=0.000,p=0.000;p=0.023,p=0.002,p=0.000;p=0.003,p=0.000,p=0.000);The expression of VDCCs mRNA was significantly increased in SAE and SAEOP groups(p=0.012,p=0.027).while there was no significant increase in SOP group(p=0.050).Compared to the SAE group,the SAEOP group Laminin β2 The expression of mRNA and protein,as well as the expression of VDCCs and Bassoon mRNA,showed a further upward trend,but there was no significant difference(p=0.156,p=0.332,p=0.734,p=0.850).Conclusions:(1)By making an aging model with D-galactose,skeletal muscle mass and function can be reduced,inducing the formation of sarcopenia.(2)When D-gal induces aging,FoxO1a is activated in skeletal muscle,which upregulates the expression of Atrogin-1,leading to increased protein breakdown in skeletal muscle.This may be one of the important mechanisms underlying the formation of sarcopenia caused by aging.However,aerobic exercise or supplementation with OP during the formation of D-gal induced sarcopenia can effectively inhibit the activity of FoxOla and the expression of Atrogin-1,reduce the degree of protein.decomposition,and play a very important role in preventing the formation of sarcopenia.The effect of aerobic exercise combined with supplementation with oyster peptide is to some extent better than that of aerobic exercise alone.(3)During the aging process induced by D-gal,the structure of NMJ undergoes aging,resulting in a decrease in the transmission efficiency of NMJ,which may be one of the important physiological mechanisms underlying the occurrence of sarcopenia caused by aging.However,during the process of D-gal induced myopenia formation,Aerobic exercise or oyster peptide supplementation upregulates the expression of VDCCs and Bassoon by promoting the expression of lamininβ2 in skeletal muscle,delay the aging of NMJ and the decrease in transmission efficiency during aging,and the combination of the two has a significant gain effect.This may be an important biological mechanism for aerobic exercise and OP supplementation to prevent the formation of NMJ aging induced myopenia.