| Myostatin(MSTN)is a member of TGF-β superfamily,which plays a negative role in regulating muscle growth.It is mainly expressed in animal skeletal muscle.Myostatin propeptide(MSTN pro)can combine with it and inhibit its function,so as to achieve the function of promoting muscle growth.In order to investigate the effect of porcine myostatin propeptide eukaryotic expression vector combined with Lactobacillus rhamnosus on muscle development and immune function of mice,in this study,64 4-week-old male Kunming mice were placed in the standard animal feeding room with room temperature of 20-25 ℃ and relative humidity of 50%-70%,fed with basic diet and free drinking water.After a week of adaptation,they were randomly divided into4 groups: A,B,C and D: normal saline + empty vector(NS + pc DNA3.1(+)),empty vector + lactic acid bacteria(pc DNA3.1(+)+ LGG),normal saline + porcine myostatin propeptide(NS + pc DNA3.1(+)-MSTN pro Group,pc DNA3.1(+)-MSTN pro + LGG group,16 rats in each group.On day 1 and 16,30 μL 25%sucrose solution was injected into the left and right quadriceps femoris of each group at two points.Half an hour later,60 μL carrier was injected into the left and right quadriceps femoris of each group,and 2 m L normal saline or Lactobacillus rhamnosus was gavaged at 9 a.m every day.Eight mice were randomly selected from each group on the 15 th and 30 th day.Body weight,organ index,serum immune related factors and m RNA expression of muscle development-related factors were detected,and the microstructure of muscle fibers was observed.Results were as follows:1.The results of physical indexes showed that compared with the control group,the body mass of mice in the porcine myostatin propeptide group increased,and the thymus mass,thymus index,spleen mass and spleen index of mice in Lactobacillus group increased significantly(P<0.05).2.The results of ELISA showed that the levels of serum IFN-λ,Ig G and IL-2 were significantly higher in the Lactobacillus group than those in the control group(P<0.05).3.The results of HE staining showed that compared with the control group,the cross-sectional area of muscle fibers in the porcine myostatin propeptide group was very significantly increased(P<0.01).4.q RT PCR was used to detect the transcriptional changes of Myo D,Myo G,Myf5,Pax3,Pax7,myomaker,Smad3 and MSTN.The results showed that the m RNA expression levels of Myo D and Myf5 were significantly increased(P<0.05)and the m RNA expression level of MSTN was significantly decreased in the porcine myostatin propeptide group(P<0.05).There was no significant difference among the other groups.5.The treatment of porcine myostatin propeptide combined with lactic acid bacteria significantly increased the thymus and spleen index and the serum levels of IFN-λ,Ig G and IL-2 immune factors(P<0.05),extremely significantly increased the cross-sectional area of mouse muscle fibers(P<0.01)and significantly increased the expression levels of Myo D and Myf5 m RNA(P < 0.05)while significantly decreased the expression level of MSTN m RNA(P<0.05).In conclusion,the combination of porcine myostatin propeptide and lactobacillus could promote muscle development and improve immune function.This study will provide an important theoretical basis for the further development of genetically engineered lactic acid bacteria which can promote growth and enhance immunity. |
PDF Full Text Request