Age-related response to tryptophan pyrrolase to 17 beta-estradiol in the liver of female rats.

The activity and the induction pattern of tryptophan pyrrolase in the liver of female rats of various ages were studied with a view to investigate the mechanism of aging in relation to enzyme regulation. The level of this enzyme increases gradually upto 33-week and decreases significantly thereafter with increasing age. Estradiol induces this enzyme significantly in both the normal and ovariectomized rats of all the ages. However, the degree of induction is different in different age groups. Highest degree of induction is observed in mature (13-week) rats. Induction of the enzyme by estradiol is actinomycin D-sensitive.