Abstract
Tamoxifen has recently been shown to suppress the growth and secretion of prolactin (PRL)-secreting pituitary tumors in rats. In the present study pretreatment for 36 h with tamoxifen did not modify the suppressive action of bromocriptine on PRL secretion in 2 patients with a prolactinoma and low plasma 17β-estradiol levels, while in 2 patients with acromegaly tamoxifen did not influence the lack of effect of bromocriptine on growth hormone (GH) secretion. In one patient with a presumably “mixed” GH-PRL secreting pituitary tumor tamoxifen had a suppressive action on hormone release. This patient had been free of complaints with normalized plasma GH and PRL concentrations for 3 yr with as low as 5 mg bromocriptine per day. Thereafter the pituitary tumor “escaped” from bromocriptine treatment, as evidenced by elevated plasma GH and PRL levels and return of the complaints, despite of an increased daily dose of bromocriptine. Plasma GH and PRL levels increased significantly at the time of ovulation and became lower thereafter parallel with the decrease in the plasma 17β-estradiol concentration. Addition of tamoxifen (20 mg/day) to bromocriptine (10 mg/day) therapy had a beneficial effect on the clinical symptoms and normalized the circulating GH levels during a treatment period of 3 months. In patients with pituitary tumors whose hormone secretion “escapes” from bromocriptine treatment, the administration of tamoxifen should be considered. The negative results, obtained with short-term administration of tamoxifen in 4 patients with pituitary tumors and low estrogen levels, do not point to a general usefulness of this drug in this type of patients.
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Nagy I., Valdenegro C.A., Login I.S., MacLeod R.M. Antiestrogens decrease prolactin synthesis and enzyme activities in the anterior pituitary of rats. Proc. of 61st Annual Meeting of the Endocrine Society, Anaheim, 1979, p. 116.
Quijada M. de, Timmermans H.A.T., Lamberts S.W.J. Tamoxifen suppresses the growth of prolactin secreting rat pituitary tumors and normal prolactin synthesis. J. Endocrinol. 86: 109, 1980.
Quijada M. de, Timmermans H.A.T., Lamberts S.W.J., MacLeod R.M. Tamoxifen enhances the sensitivity of dispersed prolactin secreting pituitary tumor cells to dopamine and bromocriptine. Endocrinology. 106: 702, 1980.
De Jong F.H., Hey A.H, van der Molen H.J. Effect of gonadotrophins on the secretion of oestradiol-17β and testosterone by the rat testis. J. Endocrinol. 57: 277, 1973.
Jordan V.C., Koerner S., Robinson C. Inhibition of oestrogen-stimulated prolactin release by anti-oestrogens. J. Endocrinol. 65: 151, 1975.
Groom G.V., Griffiths K. Effect of the anti-oestrogen tamoxifen on plasma levels of luteinising hormone, follicle-stimulating hormone, prolactin, oestradiol and progesterone in normal pre-men-strual women. J. Endocrinol. 70: 421, 1976.
Masala A., Delitala G., Lo Dico G., Stoppelli I., Alagna S., Devilla L. Inhibition of lactation and inhibition of prolactin release after mechanical breast stimulation in puerperal women given tamoxifen placebo. Br. J. Obstet. Gynaecol. 85: 134, 1978.
Golder MP., Phillips M.E.A., Fahmy D.R., Preece P.E., Jones V., Henk J.M., Griffiths K. Plasma hormones in patients with advanced breast cancer treated with tamoxifen. Eur. J. Cancer 12: 719, 1976.
Willis H.J., London D.R., Ward H.W.C., Butt W.R., Lynch S.S., Rudd B.T. Recurrent breast cancer treated with the antioestrogen tamoxifen: correlation between hormonal changes and clinical course. Br. Med. J. 1: 425, 1977.
Beaulieu N., Zeytinoglu F., Labrie F. Reversal by 17β-oestradiol of the inhibitory action of dopamine agonists on prolactin release at the anterior pituitary level. Endocrinology 102: 192, 1978.
Gala R.R., Boss R.P. Serum prolactin levels of rats under continuous estrogen stimulation and 2-br-α-ergocryptine (CB-154) injections. Proc. Soc. Exp. Biol. Med. 149: 330, 1975.
Sachdev Y., Gomez-Pan A., Tunbridge W.M.G., Duns A., Weightman D.R., Hall R., Goolamali S.K. Bromocriptine therapy in acromegaly. Lancet 2: 1164, 1975.
Lamberts S.W.J., Klijn J.G.M., Kwa G.H., Birkenhäger J.C. The dynamics of growth hormone and prolactin secre tion in acromegalic patients with “mixed” pituitary tumors. Acta Endocrinol. (Kbh.) 90: 198, 1979.
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On leave from Dept. of Physiology, University de los Andes, Mérida, Venezuela.
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Lamberts, S.W.J., de Quijada, M. & Klijn, J.G.M. The effect of tamoxifen on GH and PRL secretion by human pituitary tumors. J Endocrinol Invest 3, 343–347 (1980). https://doi.org/10.1007/BF03349368
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DOI: https://doi.org/10.1007/BF03349368