Abstract. The effect of prostaglandin D2 on the release of luteinizing hormone was studied in a superfusion system by superfusing human pituitary gland. Perfusion with 30 μg of prostaglandin D2 induced a significant increase of luteinizing hormone secretion. This is the first evidence of a direct effect of prostaglandin D2 on the secretion of luteinizing hormone from the human pituitary gland. This finding suggests the possible role of prostaglandin D2 in human reproductive function
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Akira Miyake, Keiichi Tasaka, Shintaro Mori, Youichi Saito, and Toshihiro Aono
Haruyoshi Nakao, Masafumi Koga, Masayo Arao, Makoto Nakao, Bunzo Sato, Susumi Kishimoto, Yoichi Saitoh, Norio Arita, and Shintaro Mori
Abstract. We have performed an enzyme-immunoassay for estrogen receptor on 56 human pituitary adenomas and compared the results with a single point estradiol binding assay. There was a significant positive correlation between the two assays of cytoplasmic estrogen receptor (r = 0.960). Normal human pituitaries (N = 2) had an estrogen receptor concentration of 17 fmol/mg protein by enzyme-immunoassay. Of 14 prolactinomas, 6 (43%) contained estrogen receptor with a concentration of 33.5 ± 7.4 (mean ± sem) fmol/mg protein. Six of 11 (55%) macroprolactinomas were estrogen receptorpositive, whereas all 3 microprolactinomas were estrogen receptor-negative. Only one (13%) of 8 GH- and PRL-secreting adenomas, and 3 of 6 (50%) gonadotropin-secreting adenomas were estrogen receptor-positive; the latter had a concentration of 13.5 ± 1.6 fmol/mg protein. Estrogen receptor was not detected in 21 pure GH-secreting adenomas and 7 nonsecreting adenomas. These results demonstrate the precise frequency of estrogen receptor in various human pituitary adenomas, since enzyme-immunoassay as well as single point estradiol binding assay could detect estrogen receptor even in small specimens. Enzyme-immunoassay is suitable for evaluation of estrogen receptor status in human pituitary adenomas.
Masafumi Koga, Haruyoshi Nakao, Masayo Arao, Bunzo Sato, Keizo Noma, Yasuhiko Morimoto, Susumu Kishimoto, Shintaro Mori, and Toru Uozumi
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 < 0.05) and fewer (P < 0.001) respectively, than those in PRL-secreting adenomas.