Hayden T J, Brennan D, Quirke K, Murphy P
Department of Zoology, University College Dublin, Belfield, Irish Republic.
J Dairy Res. 1991 Nov;58(4):401-9. doi: 10.1017/s0022029900030004.
Xanthine oxidase/dehydrogenase (XO/XDH) increases at mid gestation in mammary gland but not in liver of the mouse and remains elevated until the pups are weaned at 20 d post partum. The increase in enzyme activity is due neither to alteration in activators or inhibitors nor to a production of a variant enzyme with altered catalytic properties. The increase is preceded in vivo by a surge of prolactin-like activity (placental lactogen) in plasma, and prolactin is required for induction of XO/XDH in explant culture in vitro. Induction of XO/XDH in vivo and in vitro precedes the full histological differentiation of the gland. In addition, induction of XO/XDH in vitro occurs more rapidly and at lower concentrations of prolactin than does histological differentiation. Thus although XO/XDH is present in milk, increased XO/XDH activity is an early event in mammogenesis in vivo and in vitro rather than a terminal component of differentiation.
黄嘌呤氧化酶/脱氢酶（XO/XDH）在小鼠妊娠中期乳腺中增加，但在肝脏中不增加，并一直保持升高，直到产后20天幼崽断奶。酶活性的增加既不是由于激活剂或抑制剂的改变，也不是由于产生了具有改变催化特性的变体酶。在体内，血浆中催乳素样活性（胎盘催乳素）激增先于酶活性增加，并且催乳素是体外外植体培养中诱导XO/XDH所必需的。体内和体外XO/XDH的诱导先于腺体的完全组织学分化。此外，体外XO/XDH的诱导比组织学分化发生得更快，且所需的催乳素浓度更低。因此，尽管XO/XDH存在于乳汁中，但XO/XDH活性增加是体内和体外乳腺发生的早期事件，而非分化的终末成分。
