Soy protein diet prevents hypermethioninemia caused by portacaval shunt in rats.
In hepatic disorders, abnormal plasma amino acid profiles are observed. In this study, we examined whether soy protein isolate (SPI) improved plasma methionine concentration in the model animals. Portacaval shunt (PCS) increased alanine aminotransferase (ALT) activity and methionine concentration in blood of rats fed a 40% casein diet supplemented with 0.6% methionine (casein-M diet). A 40% SPI diet supplemented with 1.28% methionine (SPI-M diet), which contained the same amount of methionine as that in 40% casein-M diet, normalized plasma ALT activity and methionine level in PCS rats. These effects of a SPI diet may be due to its amino acid composition, since an amino acid mixture diet mimicking a 40% SPI-M diet was also effective to hypermethioninemia of PCS rats. To find key enzymes for the beneficial effect of soy protein, we examined effects of a 40% SPI-M or casein-M diet on the activities of three methionine-metabolizing enzymes in liver of PCS rats. A SPI-M diet stimulated only the activity of cystathionine gamma-lyase, compared with a casein-M diet. A SPI diet has a preventive effect on hypermethioninemia, at least in part, by stimulating cystathionine gamma-lyase activity in liver and may be used for nutritional management of liver disorders with hypermethioninemia.
Shimooka
Rie
R
Department of Nutrition and Health Promotion, Faculty for Human Life Science, Hiroshima Jogakuin University, Hiroshima.
Yasuhiro
Kido
K
Chiba
Naoko
N
Tanaka
Junko
J
Rokutan
Kazuhito
K
Furochi
Harumi
H
Hirasaka
Katsuya
K
Nikawa
Takeshi
T
Kishi
Kyoichi
K
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D002364:Caseins / Q000494:pharmacology / Q000627:therapeutic use; D003540:Cystathionine / Q000097:blood; D004044:Dietary Proteins / Q000494:pharmacology / Q000627:therapeutic use*; D019587:Dietary Supplements; D008107:Liver Diseases / Q000097:blood / Q000150:complications; D008297:Male; D008659:Metabolic Diseases / Q000097:blood / Q000209:etiology* / Q000517:prevention & control*; D008715:Methionine / Q000097:blood* / Q000494:pharmacology / Q000627:therapeutic use; D011167:Portacaval Shunt, Surgical / Q000009:adverse effects*; D051381:Rats; D017208:Rats, Wistar; D030262:Soybean Proteins / Q000494:pharmacology / Q000627:therapeutic use*
D002364:Caseins; D004044:Dietary Proteins; D030262:Soybean Proteins; D003540:Cystathionine; D008715:Methionine; D000410:Alanine Transaminase