Sinha Y N, Klemcke H G, Maurer R R, Jacobsen B P
Lutcher Brown Department of Biochemistry, Whittier Institute for Diabetes and Endocrinology, Scripps Memorial Hospital, La Jolla, California 92037.
Proc Soc Exp Biol Med. 1990 Sep;194(4):293-300. doi: 10.3181/00379727-194-43094.
Although prolactin (PRL) and growth hormone (GH) were long considered to be nonglycoprotein hormones of the pituitary, glycosylated forms of these hormones have nevertheless been discovered in recent years. We determined the ontogeny of glycosylated and nonglycosylated PRL and GH during the fetal life of the pig, an animal in whose pituitary the glycosylated variant of PRL has been found in high (40%) concentrations. Swine fetuses of both sexes from lean and obese animals of Duroc x Yorkshire crosses were examined at 60, 75, 90, and 105 days of age. No appreciable differences related to sex or phenotype were noted in any of the parameters measured; therefore, data for all animals within an age group were combined. Such averages revealed considerable amounts of GH in the fetal pituitary as early as 60 days of age, whereas PRL, although detectable by radioimmunoassay and immunoblotting at all ages tested, was not present in significant amounts until 105 days of age. From its first appearance, however, almost 70% of the PRL synthesized in the fetal pituitary was of the glycosylated type. In contrast to PRL, both the glycosylated and nonglycosylated forms of GH showed a steady rate of increase throughout the observation period. The immunoblotting analyses also revealed in the fetal pituitary several intensely staining 8- to 12-kDa PRL-immunoreactive peptides of unknown identity. The occurrence of significantly greater concentrations of glycosylated PRL than of non-glycosylated PRL in the fetal pituitary during late gestation offers new possibilities for the role of this hormone in the development of swine fetus.
尽管催乳素（PRL）和生长激素（GH）长期以来被认为是垂体的非糖蛋白激素，但近年来仍发现了这些激素的糖基化形式。我们确定了猪胎儿期糖基化和非糖基化PRL及GH的个体发生情况，猪的垂体中已发现高浓度（40%）的PRL糖基化变体。对杜洛克×约克夏杂交的瘦肉型和肥胖型动物的雌雄猪胎儿在60、75、90和105日龄时进行了检查。在所测量的任何参数中均未发现与性别或表型相关的明显差异；因此，将一个年龄组内所有动物的数据进行了合并。这些平均值显示，早在60日龄时胎儿垂体中就有相当数量的GH，而PRL虽然在所有测试年龄均可通过放射免疫测定和免疫印迹法检测到，但直到105日龄时才大量存在。然而，从其首次出现起，胎儿垂体中合成的PRL几乎70%是糖基化类型。与PRL不同，GH的糖基化和非糖基化形式在整个观察期内均呈现稳定的增加速率。免疫印迹分析还在胎儿垂体中发现了几种身份不明的、强烈染色的8至12 kDa的PRL免疫反应性肽。妊娠后期胎儿垂体中糖基化PRL的浓度明显高于非糖基化PRL，这为该激素在猪胎儿发育中的作用提供了新的可能性。
