Cabergoline modulation of alpha-subunits and FSH secretion in a gonadotroph adenoma

Most non-functioning pituitary adenomas respond poorly to medical therapy. We describe the case of a 62-year-old man who presented with clinical featu res of an invasive macroadenoma. Baseline hormonal evaluation revealed incr eased FSH and alpha-subunit (alpha-SU) levels. Transsphenoidal exeresis fol lowed by radiotherapy (RT) was performed. Almost all neoplastic cells were intensely immunoreactive for alpha-SU. On PCR analysis, specific amplificat ion products were observed for somatostatin 2, 3 and 5 receptors as well as for both short and long isoforms of the dopamine D2 receptor. In vitro, al pha-SU and FSH were released into the medium by adenoma cells and increased after TRH stimulation. After surgery, alpha-SU and FSH levels were still e levated. Short-term slow-release lanreotide treatment did not modify either alpha-SU or FSH levels, Cabergoline was started and a fast and long-lastin g decrease in alpha-SU and, to a lesser extent, in FSH was observed. The tu mor remnant was unmodified on magnetic resonance imaging 3 years after surg ery and RT. This case report shows that the in vitro expression of somatost atin receptors may not be directly associated to the in vivo response of al pha-SU and FSH to lanreotide, probably because of a functional uncoupling o f the receptors. Cabergoline should be considered as an effective therapy f or hormonal, and perhaps proliferative, control of gonadotroph adenoma remn ants before the effects of RT are fully effective. (C) 2000, Editrice Kurti s.