[Selective inhibition of hepatic gluconeogenesis gy tryptophan administration]

The levels of quinolinic acid in liver and kidney and the gluconeogenic capacity in these tissues were determined in rats treated with tryptophan. The administration of this aminoacid produced a high increase in the hepatic quinolinic acid concentrations fed and 48 h. starved rats. On the contrary, only slight variations in the concentrations of renal quinolinic acid were observed. The highest value raised in these conditions was three times lower than Ki of the quinolinic acid for the phosphoenolpyruvate carboxykinase. These results suggest that tryptophan administration originates a selective inhibition of hepatic gluconeogenesis.