Hormone secretion by cell culture of human GH-PRL secreting pituitary adenomas: effects of bromocriptine

Abstract

Dopamine agonists effectively reduce the secretion of prolactin (PRL) in the great majority of prolactinomas and reduce the bulk of the adenomas, as well as have partial therapeutic effect on some patients with acromegaly. The inhibitory effect of bromocriptine (BC), a dopamine agonist, on growth hormone (GH) and PRL secretion of dispersed cells from the pituitary adenomas of 16 cases of acromegaly, which secret GH and PRL simultaneously, were evaluatedin vitro. The significant inhibitory effects of BC on PRL secretion were found in 12 cases. It was also found that PRL secretion was strongly inhibited when GH was suppressed; on the contrary, when GH secretion was not suppressed, the production of PRL was not or weakly inhibited. The exact mechanism of the effects is unclear so far. It is necessary to investigate, at molecular level, the etiology of GH-PRL adenomas and its response to therapeutic agents.

Keywords

pituitary adenoma / growth hormone / prolactin / bromocriptine

References

[1] ShigeruF, ToruK, MitsuhiroO, et al. . Prolactin presents in all pituitary tumors of acromegalic patients. Hum Pathol, 1993, 24: 429-429

[2] NyquistP, LawsE R, ElliottE. Novel features of tumors that secrete both growth hormone and prolactin in acromegaly. Neurosurgery, 1994, 35: 179-179

[3] ButlerW B, KelseyE H, GoranN. Effects of serum and insulin on the sensitivity of the human breast cancer cell line MCF-7 to estrogen and anti-estrogens. Cancer Res, 1983, 41: 82-82

[4] AdamsE F, BrajkovichI E, MashiterK. Hormone secretion by dispersed cell cultures of human pituitary adenomas: effects of theophilline, thyrotropin-releasing hormone, somatostatin, and 2-bromo-α-ergocryptine. J Clin Endocrinol Metab, 1997, 49: 120-120

[5] FahlbuschR, GiovanelliM, BuchfelderM, et al. . Advances in the medical and surgical treatment of pituitary adenomas: the role of long-acting somatostatin analogs. J Endocrinol Invest, 1993, 16: 449-449

[6] FriedmanE, AdamsE F, HoogA, et al. . Normal structural dopamine type 2 receptor gene in prolactin-secreting and other pituitary tumors. J Clin Endocrinol Metab, 1994, 78: 568-568

[7] TodoT, BuchfelderM, ThieraufP, et al. . Immunohistochemical expression of protein kinase C type III in human pituitary adenomas. Neurosurgery, 1993, 32: 635-635

[8] LeiT, AdamsE F, BuchfelderM, et al. . Relationship between protein kinase C and adenylyl cyclase activity in the regulation of growth hormone secretion by human pituitary somatotrophinomas. Neurosurgery, 1996, 39: 569-569