Basic nutritional investigationAscorbic acid deficiency increases endotoxin influx to portal blood and liver inflammatory gene expressions in ODS rats

- Ascorbic acid (AsA) deficiency elevates portal blood endotoxin concentration in Osteogenic Disorder Shionogi (ODS) rats.
- AsA deficiency elevates serum interleukin-1β and interleukin-6 concentrations in ODS rats.
- AsA deficiency stimulates hepatic inflammation-related gene expressions.
- Endotoxemia caused by AsA deficiency may lead to hepatic inflammation.
- ODS rat is a useful model of investigating the physiological role of AsA in humans.

ObjectiveThe aim of this study was to determine whether ascorbic acid (AsA) deficiency-induced endotoxin influx into portal blood from the gastrointestinal tract contributes to the inflammatory changes in the liver.MethodThe mechanisms by which AsA deficiency provokes inflammatory changes in the liver were investigated in Osteogenic Disorder Shionogi (ODS) rats (which are unable to synthesize AsA). Male ODS rats (6-wk-old) were fed a diet containing sufficient (300 mg/kg) AsA (control group) or a diet without AsA (AsA-deficient group) for 14 or 18 d.ResultsOn day 14, the hepatic mRNA levels of acute-phase proteins and inflammation-related genes were significantly higher in the AsA-deficient group than the control group, and these elevations by AsA deficiency were exacerbated on day 18. The serum concentrations of interleukin (IL)-1β and IL-6, which induce acute-phase proteins in the liver, were also significantly elevated on day 14 in the AsA-deficient group compared with the respective values in the control group. IL-1β mRNA levels in the liver, spleen, and lung were increased by AsA deficiency. Moreover, on both days 14 and 18, the portal blood endotoxin concentration was significantly higher in the AsA-deficient group than in the control group, and a significant correlation between serum IL-1β concentrations and portal endotoxin concentrations was found in AsA-deficient rats. In the histologic analysis of the ileum tissues, the number of goblet cells per villi was increased by AsA deficiency.ConclusionThese results suggest that AsA deficiency-induced endotoxin influx into portal blood from the gastrointestinal tract contributes to the inflammatory changes in the liver.