GONADOTROPIN-RELEASING-HORMONE AND GONADOTROPIN-RELEASING-HORMONE RECEPTOR MESSENGER RIBONUCLEIC-ACIDS EXPRESSION IN NONTUMOROUS AND NEOPLASTIC PITUITARIES

In the nontumorous pituitary, GnRH stimulates the release and synthesi s of LH and FSH by gonadotroph cells via the GnRH receptor (GnRH-R). L ittle is known, however, about expression of GnRH and GnRH-R messenger RNAs (mRNAs) in nontumorous pituitary tissue and in adenomas. To lear n more about the distribution and regulatory roles of GnRH and its rec eptor, we investigated the expression of both GnRH and GnRH-R mRNAs in nontumorous human pituitary and in various types of pituitary adenoma s using the RT-PCR, in situ hybridization, and in situ hybridization i n combination with RT-PCR (in situ RT-PCR). Using RT-PCR, GnRH mRNA wa s found to be expressed in normal human pituitaries and in all types o f adenomas. Similarly, GnRH-R mRNA was expressed in nontumorous human pituitaries and in most, but not all, adenomas. These included 5 gonad otroph adenomas, 6 null cell adenomas, 1 of 2 GH-producing tumors, and 1 of 2 ACTH-producing adenomas, but not in the 2 PRL-producing adenom as examined. In situ hybridization studies showed GnRH and GnRH-R mRNA s in all 3 nontumorous pituitaries and in 12 of 33 (36.4%) and 10 of 3 3 adenomas (30.3%), respectively. Using an indirect in situ RT-PCR tec hnique to increase the sensitivity of the in situ localization, GnRH a nd GnRH-R mRNAs were detected in 29 (87.9%) and 25 (75.8%) of 33 adeno mas, respectively. This is the first report of the localization of GnR H and GnRH-R mRNAs in individual pituitary adenoma cells using in situ RT-PCR. The frequent expression of GnRH and GnRH-R mRNAs in pituitary cells suggests that GnRH has autocrine/paracrine functions in nontumo rous and neoplastic pituitary tissues.