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Demonstration of specific dopamine receptors on human pituitary adenomas


Dopamine receptors on human pituitary adenoma membranes were characterized using [3H] spiperone as the radioligand. The specific [3H]spiperone binding sites on prolactin (PRL)-secreting adenoma membranes were recognized as a dopamine receptor, based upon the data showing high affinity binding, saturability, specificity, temperature dependence, and reversibility. All of 14 PRL-secreting adenomas had high affinity dopamine receptors, with a dissociation constant (Kd) of 0.85 +/- 0.11 nmol/l (mean +/- SEM) and a maximal binding capacity (Bmax) of 428 +/- 48.6 fmol/mg protein. Among 14 growth hormone (GH)-secreting adenomas examined, 8 (57%) had dopamine receptors with a Kd of 1.90 +/- 0.47 nmol/l and a Bmax of 131 +/- 36.9 fmol/mg protein. Furthermore, 15 of 24 (58%) nonsecreting pituitary adenomas also had dopamine receptors with a Kd of 1.86 +/- 0.37 nmol/l and a Bmax of 162 +/- 26.0 fmol/mg protein. These results indicate that some GH-secreting adenomas as well as some nonsecreting pituitary adenomas contain dopamine receptors. But their affinity and number of binding sites are significantly lower (P less than 0.05) and fewer (P less than 0.001) respectively, than those in PRL-secreting adenomas.

Type Journal
ISBN 0001-5598 (Print)
Authors Koga, M.;Nakao, H.;Arao, M.;Sato, B.;Noma, K.;Morimoto, Y.;Kishimoto, S.;Mori, S.;Uozumi, T. :
Publisher Name Acta Endocrinol (Copenh)
Published Date 1987-01-01
Published Volume 114
Published Issue 4
Published Pages 595-602
Status Published in-print
URL link to publisher's version