Effects Of CrPyr On Protein Metabolism In Rats

Creatine pyruvate (CrPyr) is a novel nutrient supplements which can promote energy production in athletic process, so as to lengthen exercise time and improve muscular endurance and explosive power. The major effective compositions of CrPyr are pyruvic acid and creatine, which also are the physiological metabolic intermediate in the organism. Pyruvic acid can increase the metabolic energy expenditure, and then facilitate the breakdown of body fats. Meanwhile, ATP generated by the above process, delivers its high-energy phosphate bond to creatine, so that it can enhance protein synthesis. With both the functions and characters of pyruvic acid and creatine, CrPyr is known as "difunctional nutriment", accordingly. At present, researches related to CrPyr were primarily focused on Exercise Physiology, and the impact of CrPyr on protein metabolism is not yet reported. So, a study was carried out for a preliminary investigation of the influences of CrPyr on protein metabolism in adult male SD rats. The purpose of this study is to provide theoretical basis and experimental evidence for CrPyr regulation on protein accretion in rats.1 Effects of Creatine Pyruvate on Protein Metabolism Related Biochemical Parameters in RatsForty healthy adult male SD rats were randomly divided into control group (n=10) and teat groep (n=30). CrPyr (dissolved in physiological saline) in dosage of 750 (low dosage group, n=10),1500 (middle dosage group, n=10) and 3000 (high dosage group, n=10) mg/kg BW were administered to rats daily by gavage respectively, and an equal volume of physiological saline was administered to rats of control group daily by gavage, for 42 days. All rats had free access to feed and drinking water. The body weight and feed intake was measured respectively per day. After the rats were slaughtered, blood, liver and left leg muscle were gathered to detect the blood sugar (BS), hepatic glycogen, muscle glycogen, total protein (TP), blood urea nitrogen (BUN), creatinine (Cr), insulin-like growth factors-1 (IGF-1), activity of the hepatic glutamic pyruvic transaminase (GPT) and the hepatic glutamic oxalacetic transaminase (GOT), activity of creatine kinase (CK) in both serum and leg muscle, and content of nucleic acid and RNA/DNA ratio in leg muscle. The result shown that body weight, weight gain, average daily weight gain were notable lower, as compared with the control group. Meanwhile, the abdominal fat content had no significant difference, as compared with the control group, however the tendency of decrease was found. The average daily feed intake was extremely significantly lower at 1500,3000 mg CrPyr/kg BW, and the relative leg muscle weight was significantly elevated at the same time. The content of TP was significantly higher in low group. All three test groups'activity of GPT raised strikingly, while the activity of GOT had a tendency of increase. No notable differences were observed in the activity of CK in both serum and leg muscle treated with CrPyr. Add CrPyr had no significant influence on BUN, IGF-1 and Cr in serum. Compared to the control group, rats fed with three dosages of CrPyr resulted in a pronounced higher level of the concentration of RNA. Moreover, the RNA/DNA ratio of middle and high group in leg muscle was elevated remarkably. These results indicated that the administration of CrPyr to rats reduced fat deposition, enhanced protein synthesis and promoted protein accretion, which manifested by the increase of relative leg muscle weight.2 Impacts of Creatine Pyruvate on Amino Acid Profiles in Serum and Other Tissues in RatsThe experiment design was same as above study. The serum, heart, liver and left leg muscle were gathered after the rats were slaughtered. A pre-column deviation procedure of O-Phthaldialdelhyde (OPA) was used for the determination of the variation of amino acid profile in the above four tissues. The data shown that, the administration of CrPyr could increase the contents of Asn and Ser in serum, as compared with the control group. By adding CrPyr, the concentration of Gln in serum was extremely significant lower than the control group. In contrast, the concentration of Gln in leg muscle was raised strikingly. Compared to the control group, CrPyr could elevate the contents of main glycogenic amino acids (include Asp, Glu, Asn, Ser, Gln, Thr, Arg and Ala) in leg muscle, while the contents of BCAA was remarkably lower. But the amino acid profile in liver had no remarkable differences with the control group. The above consequences manifested that, the administration of CrPyr to rats remarkably elevated the concentrations of glycogenic amino acids in both serum and leg muscle, by enhancing the energy supply. Then the increased glycogenic amino acids would provide energy foundation and raw materials for protein synthesis. The increase of protein synthesis consumed BCAA; therefore the concentrations of BCAA in leg muscle were notably lower than the control group.3 Influences of Creatine Pyruvate on mRNA Transcriptional Level of Protein Metabolism Related Genes in RatsThe experiment design was same as experiment 1. The mRNA transcriptional level of hepatic insulin-like growth factor-1 (IGF-1) genes, and insulin-like growth factor receptor-1 (IGFR-1), myogenin (MyoG), myostatin (MSTN),μ-calpain (CAPN-1) and calpastatin (CAST) genes in leg muscle were determined using the real time RT-PCR. The results shown that, as compared with the control group, the administration of CrPyr had no significant effect on mRNA transcriptional level of IGF-1 genes in liver. This is similar to the alternant tendency of content of IGF-1 in serum. The mRNA transcriptional level of IGFR-1 in leg muscle had no significantly difference with the control group too. In leg muscle, MyoG mRNA transcriptional level was raised strikingly with fed 1500 and 3000 mg CrPyr/kg BW. Meanwhile, MSTN mRNA transcriptional level was lower than the control group, but the variance was not significant. By adding 3000 mg CrPyr/kg BW, CAPN-1 mRNA transcriptional level was extremely higher than the control group, and the mRNA transcriptional level of CAST were extremely higher than the control group, with fed 1500 and 3000 mg CrPyr/kg BW. This study indicates that, the administration of CrPyr can facilitate leg muscle's development and growth, by up-regulating the mRNA transcriptional level of MyoG gene and down-regulating MyoG's suppressor gene. Moreover, CrPyr may suppress the protein degradation of leg muscle by raising the mRNA transcriptional level of CAST gene. But the precise mechanisms are not distinct yet.