Effects Of Amino Acids On Blood Glucose And Involved Mechanisms

Aim: this study was to investigate the effects of amino acids on blood glucose inKM mice and involved mechanism. Method and results:(1) in order to select the mosteffective amino acid to lower blood glucose level, KM mice were allocated into2groupsof fifteen rats each: glucose group (2g/kg) and amino acids group [amino acid (2g/kg)+glucose (2g/kg)], amino acid and glucose were given by stomach tube. Theconcentration of blood glucose was determined at0.5h,1h and2h after treatment. Theresults showed that AUC and blood glucose level at0.5h,1h and2h were lower inL-leucine group than in D-leucine. as well as AUC and blood glucose level at0.5h,1hand2h were lower in L-leucine and L-tryptophan group than in glucose group(P<0.01),AUC and blood glucose level at0.5h and1h were lower in L-valine, L-isoleucine,L-methionine, L-threonine, L-lysine, L-glycine, L-arginine, L-alanine, L-cysteine,L-proline group than in glucose group(P<0.01). Although AUC and blood glucose at0.5h was lower in L-phenylalanine and L-serine group than in control group, inaddition,the level of blood glucose at0.5h did not shows any significant differencebetween L-aspartate, L-tyrosine, L-glutamate, L-histidine and L-asparagine group andcontrol group (P>0.05). Above results suggested that L-leucine was most effective in allamino acids.(2) in order to explore the most effective concentration of leucine to lowerblood serum level, mice were supplemented with low dose of leucine (0.7g/kgleucine+2g/kg glucose) or high dose of leucine (2g/kg leucine+2g/kg glucose) or glucose(2.0g/kg), the results showed that blood glucose level at0.5h was smaller in high dose ofleucine than in low dose of leucine. Above results suggested that the most effective doseof leucine to decrease blood glucose level was2.0g/kg.(3) in order to investigate theeffects of leucine on blood glucose after taking starch. mice were randomly given starch(2g/kg) or leucine (2g/kg leucine+2g/kg starch), the results showed that the blood glucose at0.5h and1h was lower in leucine group than in starch group, above resultssuggested that leucine decreased blood glucose level after taking starch.(4) in order tostudy the mechanism of the effects of leucine on blood glucose, serum were taken after0.5h after administration mice with leucine, serum insulin and Glucagonlike peptide-1(GLP-1) were measured by Elisa kit.(5) the MIN-6cell were cultured with the modifiedmedium containing different dose of leucine for1h、6h、24h、48h. Medium andcell lysis solution were collected for insulin assay. Animal results indicated that serumconcentration of insulin and GLP-1was greater in high dose of leucine (2g/kg) than incontrol group. Cell data showed that insulin level in cell medium and cell lysis werehigher in leucine group than in control group at1h、6h、24h. Conclusions: All essentialamino acids and some of nonessential amino can significantly decrease postprandialglucose level in KM mice. The effects of leucine on postprandial blood glucose levelwere much better than other amino acids through affecting insulin and GLP-1secretion.