Fasting enhances p-Cresol production in the rat intestinal tract.
p-Cresol is a metabolite of aromatic amino acid metabolism produced by intestinal microflora, and its formation is influenced by intestinal conditions. Fasting drastically changes intestinal conditions. However, the effect of fasting on p-cresol production is unclear. In this study, serum and cecal p-cresol levels were determined in non-fasted rats and in rats fasting for either 12 or 18 h. Serum p-cresol increased significantly with 12-h fasting (3.44 +/- 2.15 nmol/ml; P<0.05) and 18-h fasting (5.40 +/- 2.20; P<0.001) as compared to the level in the non-fasted rats (1.02 +/- 0.50). Cecal p-cresol levels of the 12-h fasted (272.6 +/- 313.2 nmol/cecum) and 18-h fasted rats (436.6 +/- 190.8; P<0.01) were higher than those in non-fasted rats (27.1 +/- 21.9). The total cecal protein in content did not change with 18-h fasting. However, the cecal protein concentration increased significantly with fasting (P<0.001), and correlated closely with total cecal p-cresol contents (P<0.001). These results indicate that fasting enhances p-cresol production in the rat cecum, resulting in accumulation of serum p-cresol. We presume that the increase in p-cresol produced by fasting is related to the enhancement of bacterial nitrogen metabolism via an increased concentration of endogenous protein in the cecum.
Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi, Tokyo 186-8650, Japan.
Koji
K
Kawakami
Kenji
K
Kojima
Ikuyo
I
Makino
Ikuo
I
Kato
Masaharu
M
Onoue
D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D001835:Body Weight; D002432:Cecum / Q000378:metabolism* / Q000382:microbiology; D003408:Cresols / Q000378:metabolism*; D004435:Eating; D005508:Food Deprivation; D006403:Hematologic Tests; D007211:Indoles / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013047:Specific Pathogen-Free Organisms; D013997:Time Factors
D003408:Cresols; D007211:Indoles; C032538:4-cresol; D000641:Ammonia; C030374:indole