Matthews S G, Han X, Lu F, Challis J R
Lawson Research Institute, Department of Physiology, University of Western Ontario, St Joseph's Health Centre, London, Canada.
J Mol Endocrinol. 1994 Oct;13(2):175-85. doi: 10.1677/jme.0.0130175.
Ontogenic changes in pituitary pro-opiomelanocortin (POMC) mRNA and prolactin (PRL) mRNA were examined during gestation and early neonatal life using in situ hybridization histochemistry. Pituitaries were harvested from fetuses at days 60-80, 100-120, 135-140 and 142-143 of gestation and at term, and from lambs at days 1-7 and 30-60 of age and adults. POMC mRNA, present by day 60, rose during mid- and late gestation. Concurrently there was a change in corticotroph distribution, resulting in a relatively greater quantity of POMC mRNA at the base of the pars distalis. At term, there was a significant (P < 0.05) further elevation of POMC mRNA. POMC mRNA levels remained high in the newborn lamb but decreased in the adult. Cells in the pars intermedia expressed large amounts of POMC mRNA early in fetal life and this pattern persisted throughout gestation and into the neonatal period. Changes in the expression of the POMC gene correlated closely with the presence of immunoreactive (ir)ACTH in the pituitary; in fetuses the proportion of irACTH-positive cells rose to 10% of pars distalis cells by day 100 and did not change significantly thereafter. The lactotrophs contained PRL mRNA by day 60, and the quantity increased towards parturition (P < 0.05). PRL mRNA subsequently decreased in the neonate, but rose as the lamb matured. These results indicate that in the fetal pituitary: (1) the POMC gene is highly expressed during gestation in both the pars distalis and the pars intermedia, (2) changes in the amounts of POMC mRNA and PRL mRNA in the pars distalis correlate with the distribution of irACTH and irPRL respectively, and (3) POMC mRNA is distributed primarily in the inferior aspect of the pars distalis, and in this region its quantity is highest immediately prior to parturition.
利用原位杂交组织化学技术，在妊娠期间和新生儿早期研究了垂体阿黑皮素原（POMC）mRNA和催乳素（PRL）mRNA的个体发生变化。从妊娠60 - 80天、100 - 120天、135 - 140天、142 - 143天的胎儿以及足月胎儿、出生后1 - 7天和30 - 60天的羔羊及成年羊采集垂体。POMC mRNA在妊娠60天时就已存在，在妊娠中期和晚期增加。同时，促肾上腺皮质激素细胞分布发生变化，导致远侧部基部的POMC mRNA数量相对增加。足月时，POMC mRNA显著（P < 0.05）进一步升高。新生羔羊中POMC mRNA水平保持较高，但在成年羊中降低。中间部的细胞在胎儿早期表达大量POMC mRNA，这种模式在整个妊娠期间持续存在并持续到新生儿期。POMC基因表达的变化与垂体中免疫反应性（ir）促肾上腺皮质激素（ACTH）的存在密切相关；在胎儿中，到100天时，irACTH阳性细胞占远侧部细胞的比例升至10%，此后无显著变化。催乳素细胞在60天时含有PRL mRNA，其数量在分娩时增加（P < 0.05）。PRL mRNA随后在新生儿中减少，但随着羔羊成熟而增加。这些结果表明，在胎儿垂体中：（1）POMC基因在妊娠期间在远侧部和中间部均高度表达；（2）远侧部POMC mRNA和PRL mRNA量的变化分别与irACTH和irPRL的分布相关；（3）POMC mRNA主要分布在远侧部的下部，且在该区域其数量在分娩前立即最高。
