Comparison of hormonal secretory behavior of gonadotroph cell adenomas in vivo and in culture.

To determine whether pituitary macroadenomas associated with supranormal serum FSH concentrations represent gonadotroph cell adenomas or nonsecreting adenomas that selectively impair LH secretion by normal gonadotroph cells, we studied the secretory behavior in dispersed cell culture of three pituitary adenomas from patients who had supranormal serum FSH concentrations. Similar comparisons were made for 11 other adenomas, which were associated with the in vivo hypersecretion of alpha-subunit (n = 4) or PRL/GH (n = 4) or with no obvious hypersecretion (n = 3). Adenomas associated with supranormal serum FSH in vivo released more FSH in culture (5.1-27.0 ng/well . 24 h) than they did other hormones (TSH, less than 0.33; GH, less than 0.10; PRL, less than 0.14 ng/well . 24 h) and more FSH than did PRL/GH-secreting (less than 0.1-0.9 ng/well . 24 h) and nonsecreting (less than or equal to 0.5 ng/well . 24 h) adenomas. Adenomas associated with supranormal serum alpha-subunit in vivo released not only more alpha-subunit in culture (7.2-22.0 ng/well . 24 h) than did other adenomas (0.1-2.4 ng/well . 24 h), but two of them also released as much FSH (12.7 and 17.0 ng/well . 24 h) as did adenomas associated with supranormal serum FSH. The close correlation between the hormonal secretory behavior in vivo and that in culture of the three pituitary macroadenomas associated with supranormal serum FSH concentrations suggests that these are indeed adenomas of gonadotroph cells that are hypersecreting FSH. The release of relatively large amounts of FSH by cultured cells of adenomas that appeared to be hypersecreting only alpha-subunit in vivo suggests that at least some alpha-subunit-secreting adenomas are also gonadotroph cell adenomas.