Localization of basic fibroblast growth factor (bFGFJ) protein and mRNA in human pituitaries: regulation of bFGF mRNA by gonadotropin-releasing hormone.

Distribution of basic fibroblast growth factor (bFGF) in non-neoplastic and adenomatous human pituitaries was analyzed by immunohistochemistry, in situ, and Northern hybridization analyses. Basic FGF protein and mRNA were present in most hormone-producing cells of the non-neoplastic pituitary and in all pituitary adenomas examined. Northern hybridization analysis revealed 7.3 kb and 3.7 kb transcripts, which were most abundant in PRL-and ACTH-secreting adenomas. Three null cell and 3 gonadotroph adenomas were cultured for 7 days in the presence of 10 mol/L GnRH. There was an increase (range, 0.4-1.8-fold based on mean grain counts after in situ hybridization) in bFGF in most adenomas (5 of 6). Northern analysis showed an increase in the 7.3-kb transcript in a null-cell adenoma. Chromogranin B mRNA was also increased by Northern analysis in the same neoplasm. These results indicate that bFGF protein and mRNA are widely distributed in non-neoplastic and adenomatous human pituitaries and that the mRNA levels of bFGF in null cell and gonadotroph adenomas can be modulated by GnRH, implicating hypothalamic peptides in regulating bFGF in the anterior pituitary.