Effects Of Low Protein Diets Supplemented With Rumen-protected Amino Acid On The Expression Of Amino Acid Transporters And Glucose Transporters In The Mammary Gland Of Lactating Cows

To investigate the effects of different combinations of amino acid on the expression of amino acid transporters,glucose transporters and proteins in insulin-related signaling pathway,in this study,the feeds with different level in protein adding four kinds of essential amino acids(Met,Thr,Ile and Leu)were supplied to Holstein dairy cows,the mammary gland sample were collected and the mRNA expression and protein expression of several amino acid transporters,glucose transporters and insulin-related signal proteins in breast tissue were detected.10 lactation dairy cows were designed as 5×5 repeat Latin square.The dietary protein levels were 16%and 12.7%,and the low-protein diets were added with rumen amino acids.Theaminoacidswere0,Met(5g/d),Met+Thr(16.1g/d)and Met+Thr+Ile(18g/d)+Leu(30.9g/d).The treatment groups were called as PC group,NC group,M group,MT group and MTIL group.The results showed that:(1)The amino acid transporters LAT1,SNAT3,y~+LAT1,ASCT1,ASCT2 was significantly affected by treatment in experiment(P<0.05).And the effect on SNAT2 is tend to be significant(P=0.0649);The effect on LAT2 was not significant(P=0.2005).Compared with NC group,there is no significant difference between the expression of AATs for PC group(P>0.05).The expression of LAT1,LAT2,SNAT2,SNAT3,ASCT1and ASCT2 were decreased or tended to decreased(P<0.1)in the M and MT Groups.Compared with the M Groups,the expression of the MTIL group increased significantly(P<0.05)and with MT Groups,the expression tended to increased(P<0.1).For y~+LAT1,compared with NC group,the expression of M group and MT group increased significantly(P<0.05)and compared with M group and MT group,the expression of MTIL group decreased(P<0.05).(2)The expression of GLUT1 was affected significantly by the treatment(P<0.05),and the effect on the expression of GLUT3(P=0.0504)and GLUT8(P=0.0689)was tend to be significant.For GLUT1,compared with NC group,the expression in PC,M and MT group wasdecreasedsignificantly(P<0.05),andthereisnodifferenceinMTIL group(P>0.1);Compared with MT group,the expression in MTIL group was increased significantly(P=0.0647).(3)For insulin-related signal proteins,the expression of AKT1 was affected significantly by treatments,and the expression of INSR and IRS1 not significantly(P>0.05).Compared with NC group,the expression of AKT1 in M and MT groups decreased significantly(P<0.05);Compared with MT group,the expression of AKT1in MTIL group increased significant(P=0.3938).Conclusion:It can affect the expression of amino acid transporters,glucose transporters and signaling protein related to insulin pathway by adding rumen-protected amino acid and then regulate the function of mammary gland.