PROLACTIN RECEPTOR MESSENGER-RIBONUCLEIC-ACID IN NORMAL AND NEOPLASTIC HUMAN PITUITARY TISSUES

We examined the specific cell types in normal human pituitaries that e xpressed PRL receptor (PRL-R) messenger ribonucleic acid (mRNA) by com bined in situ hybridization and immunohistochemistry. The distribution of PRL-R mRNA in 28 pituitary adenomas was examined by in situ hybrid ization and reverse transcription-PCR in 12 cases of adenomas. In anot her set of experiments, 34 PRL adenomas fi om men, women, and bromocri ptine-treated patients were analyzed for PRL-R by in situ hybridizatio n. In the normal pituitary, PRL- and LH-producing cells had significan tly more mean grain counts per cell and higher percentages of cells po sitive for PRL-R than GH and TSH cells. PRL-R mRNA was present in all groups of adenomas by in situ hybridization and reverse transcription- PCR. PRL adenomas had a significantly higher density of labeling compa red to other adenoma types. Although there was no difference in the le vels of PRL-R mRNA in PRL adenomas from men and premenopausal and post menopausal women, patients treated with bromocriptine before pituitary surgery had significantly lower levels of PRL-R compared to all other groups. These results indicate that in the normal pituitary, PRL and LH cells have the highest level of PRL-R mRNA, whereas PRL adenomas ha ve significantly higher levels of PRL-R mRNA than other types of adeno mas, and bromocriptine treatment decreases the levels of PRL-R mRNA in PRL adenomas.