Comparison of sex hormone dependent induction of delta-aminolevulinic acid dehydratase in chick liver and oviduct

1. Comparative study on induction of hepatic and oviduct delta-aminolevulinic acid dehydratase (EC 4.2.1.24, ALAD) was performed following estradiol-17 beta and/or testosterone administration in immature female chicken (Gallus domesticus). 2. The lowest amount of estradiol for maximal induction of hepatic and oviduct ALAD activity was 2 mg/day/bird. 3. When estradiol of 2 mg/day/bird was administered for 15 days successively, induction extent of oviduct ALAD molecule was markedly larger and became approximately 144-fold in comparison with that of liver. Testosterone (2 mg/day/bird) alone did not induce both hepatic and oviduct ALAD activity. 4. Synergistic and antagonistic effect of testosterone on estradiol-induced total ALAD activity in oviduct was dependent on testosterone amount administered, whereas testosterone antagonized the inductive effect of estradiol on liver ALAD activity, independently of its amount.