Abnormal tryptophan metabolism in pregnancy and with the oral contraceptive pill. I. Specific effects of an oral estrogenic contraceptive steroid on the tryptophan oxygenase and two aminotransferase activities in livers of ovariectomized-adrenalectomized rats

Abstract

The effects of estrogenic steroids on tryptophan oxygenase (TO) pyr uvate amino transferase (PAT) and oxalacetic aminotransferase (OAT) wer e investigated in albino rats who had been ovariectomized or ovariectomy-adrenalectomized. after ovariectomy TO and PAT activities were reduced in rat liver and returned to normal by administering an estrogenic contraceptive steroid. In ovariectomized and adrenalectomized animals only the TO activity was restored PAT was unaffected. When coupled with the findings of others demonstrating a desaturation of kynurenine aminotransferase for pyridoxal phosphate following estrogen administration and the compartmentalization of Vitamin-B6 in the fetus provides a biochemical basis for increased pyridoxine needs in pregnancy and in women on the pill. The indication is that pregnancy and oral contraceptives increases the utilization of trypothan for the conversion to niacin.