Ruiz-Bravo N, Ernest M J
Proc Natl Acad Sci U S A. 1982 Jan;79(2):365-8. doi: 10.1073/pnas.79.2.365.
Tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) enzyme and mRNA activity were not detectable in day 20 fetal rat liver. Precocious induction of catalytic activity by in utero injection of dibutyryl cAMP was a direct consequence of the de novo appearance of translatable tyrosine aminotransferase mRNA. In contrast, in utero injection of hydrocortisone acetate failed to elicit fetal liver enzyme activity. This failure was due to the inability of the steroid hormone to induce the appearance of tyrosine aminotransferase mRNA activity. In fetal rat liver explants, either compound was capable of stimulating the synthesis of adult levels of enzyme and mRNA. However, catalytic and mRNA activity comparable with that seen in vivo 24 hr after birth required the concerted action of both inducers.
在胎龄20天的大鼠肝脏中未检测到酪氨酸转氨酶（L-酪氨酸：2-氧代戊二酸转氨酶，EC 2.6.1.5）的酶活性和mRNA活性。子宫内注射二丁酰环磷腺苷（dibutyryl cAMP）对催化活性的早熟诱导是可翻译的酪氨酸转氨酶mRNA从头出现的直接结果。相比之下，子宫内注射醋酸氢化可的松未能引发胎儿肝脏酶活性。这种失败是由于类固醇激素无法诱导酪氨酸转氨酶mRNA活性的出现。在胎鼠肝脏外植体中，这两种化合物中的任何一种都能够刺激成年水平的酶和mRNA的合成。然而，与出生后24小时体内所见相当的催化活性和mRNA活性需要两种诱导剂的协同作用。
