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Demonstration of specific dopamine receptors on human pituitary adenomas.

Abstract
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.
AuthorsM Koga, H Nakao, M Arao, B Sato, K Noma, Y Morimoto, S Kishimoto, S Mori, T Uozumi
JournalActa endocrinologica (Acta Endocrinol (Copenh)) Vol. 114 Issue 4 Pg. 595-602 (Apr 1987) ISSN: 0001-5598 [Print] Denmark
PMID3577589 (Publication Type: Journal Article)
Chemical References
  • Receptors, Dopamine
  • Bromocriptine
  • Spiperone
  • Prolactin
  • Growth Hormone
Topics
  • Adenoma (analysis, drug therapy, metabolism)
  • Adult
  • Bromocriptine (therapeutic use)
  • Female
  • Growth Hormone (metabolism)
  • Humans
  • Male
  • Middle Aged
  • Pituitary Neoplasms (analysis, drug therapy, metabolism)
  • Prolactin (metabolism)
  • Receptors, Dopamine (analysis)
  • Spiperone (metabolism)

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