(2)アスコルビン酸合成不能ODSラットを用いたアスコルビン酸欠乏初期に変動する遺伝子発現の解析(生命システムにおけるビタミンC)

抄録

The ODS(osteogenic disorder Shionogi) rat, which has a hereditary in ascorbic acid biosynthesis, was a useful model for investigating the physiological function of this vitamin. To find out a novel function of ascorbic acid in vivo, we looked for proteins whose levels were changed by ascorbic acid deficiency in serum and tissues of ODS rats. Male ODS rats (6-week old, body weight 〜140g) were fed a basal diet containing ascorbic acid (300mg/kg) or a diet without ascorbic acid for 14 days. As a result of screening, ascorbic acid deficiency significantly elevated the serm concentration of haptoglobin and significantly lowered those of apolipoprotein A-I and albumin. In addition, ascorbic acid deficiency significantly lowered the renal levle of kidney fatty acid-binding protein, which is synthesized as α2u-globulin in liver and thereafter located in kidney. The hepatic mRNA levels of haptoglobin and α1-acid glycoprotein (positive acute phase proteins) in the ascorbic acid-deficient rats were significantly elevated. On the contrary, the hepatic mRNA levels of apolipoprotein A-I, albumin and α2-globulin (negative acute phase proteins) in the ascorbic acid-deficient rats weresignificantly lowered. The serum concentration of interleukin 6, an inflammatory cytokine that stimulates gene expression of some positive acute phase proteins, was elevated in the ascorbic acid-deficient rats. These results demonstrate for the first time that ascorbic acid deficiency changes the acute phase protein gene expressions as seen in inflammatory response, and the mechanism of action of ascorbic acid in this phenomenon should be clarified in further studies.