Activation of tryptophan pyrrolase after chronic alcohol administration.

We have recently found decreased plasma tryptophan levels in alcoholics as well as in baboons and rats fed alcohol chronically. In the present study we investigated changes in tryptophan pyrrolase which is considered to be rate limiting for tryptophan catabolism. Rats fed alcohol chronically showed an increased activity of the enzyme in the liver and an increased formation of kynurenine after administration of a tryptophan load. It is concluded that this enhanced enzymatic activity may be responsible, at least in part, for the depressed plasma tryptophan levels we observed.