Egashira Yukari, Sato Mayuki, Saito Kuniaki, Sanada Hiroo
Laboratory of Food and Nutrition, Graduate School of Science and Technology, Chiba University, Matsudo 271-8510, Japan.
Int J Vitam Nutr Res. 2007 Mar;77(2):142-8. doi: 10.1024/0300-9831.77.2.142.
During tryptophan-niacin conversion, hepatic alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) [EC4.1.1.45] plays a key role in regulating NAD biosynthesis. ACMSD activity is greatly affected by many factors such as nutritional status and disease. The tryptophan catabolite quinolinic acid has been reported to be associated with the pathogenesis of various disorders and is a potential endogenous toxin. However the effects of dietary protein levels or dietary interaction between protein levels and fatty acid type to this process have not been investigated and are still unknown. In this study, we examined whether dietary protein level, fatty acid type, namely saturated fatty acid and polyunsaturated fatty acid, and their interaction affect serum quinolinic acid concentration in rats. Male Sprague-Dawley rats (4-weeks old) were fed with 20% casein + 10% stearic acid diet (20C10S), 20% casein + 10% linoleic acid diet (20C10L), 40% casein + 10% stearic acid diet (40C10S), or 40% casein + 10% linoleic acid diet (40C10L) for 8 days, and serum quinolinic acid concentration and ACMSD activity were determined. Serum quinolinic acid concentration was significantly increased in the 40C10L group compared with other three groups. There was also the negative correlation between the sum of liver and kidney ACMSD activities, and serum quinolinic acid concentration per tryptophan intake (r = 0.8209, p < 0.01). Increased serum QA concentrations are probably due to a decreased ACMSD activity.
在色氨酸向烟酸的转化过程中，肝脏中的α-氨基-β-羧基粘康酸-ε-半醛脱羧酶（ACMSD）[EC4.1.1.45]在调节烟酰胺腺嘌呤二核苷酸（NAD）生物合成中起关键作用。ACMSD的活性受到营养状况和疾病等多种因素的极大影响。据报道，色氨酸分解代谢产物喹啉酸与多种疾病的发病机制有关，是一种潜在的内源性毒素。然而，饮食蛋白质水平或蛋白质水平与脂肪酸类型之间的饮食相互作用对这一过程的影响尚未得到研究，仍然未知。在本研究中，我们检测了饮食蛋白质水平、脂肪酸类型（即饱和脂肪酸和多不饱和脂肪酸）及其相互作用是否会影响大鼠血清喹啉酸浓度。将雄性斯普拉格-道利大鼠（4周龄）喂食20%酪蛋白+10%硬脂酸饮食（20C10S）、20%酪蛋白+10%亚油酸饮食（20C10L）、40%酪蛋白+10%硬脂酸饮食（40C10S）或40%酪蛋白+10%亚油酸饮食（40C10L）8天，并测定血清喹啉酸浓度和ACMSD活性。与其他三组相比，40C10L组血清喹啉酸浓度显著升高。肝脏和肾脏ACMSD活性总和与每色氨酸摄入量的血清喹啉酸浓度之间也存在负相关（r = 0.8209，p < 0.01）。血清喹啉酸浓度升高可能是由于ACMSD活性降低所致。
