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F Peillon

Publications and source records attributed to F Peillon.

At least 91 records · Page 5Linked to original sources
PubMed1980

Dopaminergic receptors in human prolactin-secreting adenomas: a quantitative study.

Dopaminergic receptors were observed on the membranes of 26 human PRL-secreting adenomas. Two binding sites were found for [3H]domperidone, a selective dopamine antagonist, with a Kd1 of 0.29 +/- 0.06 nM and a Kd2 of 4.19 +/- 0.7 nM (n = 5). Bmax1 and Bmax2 (maximum numbers of binding sites, first and second sites, respectively) varied from one adenoma to another. When considering Bmax1, two different categories of PRL-secreting adenomas were distinguished, one with a concentration of receptor over 250 fmol/mg protein and others with lower concentrations of receptor (< 250 fmol/mg protein). In the latter, when considering the volume of the tumor, a higher plasma PRL level was found. Two binding sites for [3H]domperidone also were found in the normal human hypophysis with Kd values similar to those of the adenomas (0.18 +/- 0.04 and 3.95 +/- 0.35 nM). The same number of binding sites was observed in normal pituitaries and in PRL-secreting adenomas. However, when considering the density of PRL-secreting cells in the two different tissues (prolactinomas contain 2 or 3 times more PRL-secreting cells than human pituitary tissue), one may suspect a defect in the dopaminergic inhibiting control in PRL-secreting adenomas.

Adenoma↗
PubMed1980

Endocrine outcome after transsphenoidal adenomectomy for prolactinoma: prolactin levels and tumor size as predicting factors.

The level of prolactin in the serum was determined pre- and postoperatively in 90 patients who were operated upon transsphenoidally for prolactin-secreting pituitary adenomas. Twenty-three had microadenomas and 67 had macroadenomas. Those patients who were cured had a distinctly lower mean prolactin level (about 200 ng/ml or less) than those who were not cured. Of those patients whose adenomas were larger than 10 mm in diameter, only 39% were cured. The relationship between prolactin levels and tumor size and the return of menses and cure is discussed.

Adenoma↗
PubMed1979

[Demonstration of dopaminergic receptors in human pituitary adenomas secreting prolactin].

3H Domperidone binding on cellular membranes from human prolactin adenomas demonstrates the presence of two dopaminergic binding sites. The mean value of the dissociation constant (Kd) for five adenomas is of 0.29 +/- 0.14 nM for the first site and of 4.19 +/- 1.56 nM for the second site. The maximal number of binding sites (Bmax) varies from one adenoma to another. The binding is completely displaced at 30 nM of tritiated Domperidone by apomorohine, a specific dopaminergic agonist.

Adenoma↗
PubMed1979

[Vasoactive intestinal peptide (VIP): specific receptors and adenylate cyclase activation in a human prolactin-secreting pituitary tumor].

Receptors for the Vasoactive Intestinal Peptide (VIP) were characterized in particles enriched in plasma membranes obtained from a human prolactin-secreting pituiatry tumor. Native VIP inhibited competitively the binding of 125I-VIP to the particles and stimulated cyclic AMP production; both these effects were observed at concentrations of VIP as low as 10(-11)-10(-10) M, which are compatible with VIP concentrations in the hypothalamopituitary portal blood.

Adenylyl Cyclases↗
PubMed1979

[Prolactin secreting adenomas: surgical treatment and results. 120 female cases, 30 males cases (author's transl)].

Twenty one per cent of the female cases concerned microadenomas discovered because of amenorrhea with or without galactorrhea. Sixty two per cent of these cases were cured by surgery alone, against 40% of the other types of prolactin (Prl) -- secreting tumors with extra-sellar extensions which were not cured. With men, no microadenomas was discovered (although one case demonstrated their possible existence) and in the most frequent cases, tumors exhibited extra-sellar extensions sometimes very large (giant tumors). In these cases, tumoral symptoms were cured by surgery while only 5 out of 30 men recovered a normal plasma Prl. level (30 ng/ml). In all cases the prognosis was established taking into account the volume and invasive characters (at the surgical and histopathological level) of the tumors. The different therapeutical approaches of these tumors (i.e. medical treatment by CB 154, surgery of Rxtherapy) were evaluated. Anyway the necessity of an earlier diagnosis is pointed out allowing the possibility of a selective adenomectomy by a microsurgical approach.

Adenoma↗
PubMed1979

In vitro effect of dopamine and L-dopa on prolactin and growth hormone release from human pituitary adenomas.

To determine the site of action of dopaminergic drugs on human PRL and GH release from pituitary adenomas, five PRL-and five GH-secreting adenomas were incubated with and without dopamine and L-dopa. Bromocriptine was also tested in order to compare its effect to that of the other drugs. In all of the experiments except one, a decrease of PRL, which was often statistically significant, was observed. When pooling the results of the PRL-secreting adenomas, the mean levels of PRL with dopamine, L-dopa, and bromocriptine were, respectively, 49%, 55%, and 60% of the control levels. In the GH-secreting adenomas, they were 60%, 67%, and 55% of that of the control. For GH, a decrease of the release was observed in four out of five GH-secreting adenomas. When pooling the results from these tumors, the mean levels of GH with dopamine, L-dopa, and bromocriptine were, respectively, 63%, 76%, and 64% of the control levels. In one case, a significant increase of GH was observed with the three dopaminergic drugs. This study produced the following conclusions. 1) Dopamine acts directly on PRL and GH release from human pituitary adenomas; in vitro, L-dopa effects are similar (its action probably occurs after conversion to catecholamines). These observations strongly suggest the presence of dopaminergic membrane receptors on human lactotroph and somatotroph adenomatous pituitary cells. 2) In vitro hormonal results are in good agreement with in vivo dynamic tests using L-dopa and bromocriptine. 3) The paradoxical effect of dopaminergic drugs on GH secretion in acromegalic patients may be attributed to modified dopamine membrane receptors. However, the paradoxical response is not a constant feature in acromegaly, and its mechanism needs further investigations.

Adenoma↗
PubMed1979

Prolactin-secreting pituitary adenoma in a man with gigantism: a case report.

A prolactin-secreting pituitary adenoma was removed trans-sphenoidally from a 37 years old man with gigantism (218 cm). Serum levels of prolactin (PRL) were elevated pre-operatively and decreased after administration of L-Dopa with no increase after TRH as is usually observed in PRL-secreting adenomas. Growth hormone (GH) and somatomedin serum levels were normal with no modification of GH after insulin hypoglycemia, oral glucose loading or L-Dopa. Morphological examination of the tumour demonstrated the presence of lactotrophs by light and electron microscopy and by immunofluorescense staining. No somatotrophs were found. In this unique case, the relationship between a PRL-secreting adenoma and gigantism is discussed.

Adenoma↗
PubMed1975

Organ culture of human somatotrophic pituitary adenomas: ultrastructure and growth hormone production.

Ten somatotrophic adenomas removed from acromegalic patients and fragments of the non-tumoural surrounding pituitary were submitted to organ culture for periods of up to one month. Electron microscopic observation shows that these tumours retain their histological differentiation throughout the culture period. The cell morphology of the cultured tumours remains essentially unchanged and in particular the secretory granules keep their initial size (150 and 130 nm). However, the granules disappear gradually so that most of the cells look chromophobic by the 4th week of culture, and numerous lysosomes as well as autophagic figures appear at the same time. The hGH concentration in the culture medium has been measured of 4 adenomas. It is very high (10-fold greater than that from non-tumoural pituitary medium) during the first week (range 200-300 mug/ml). It still remains very high in the same experiments until the second week of culture in one experiment (200 mug/ml). After incubation of cultures with 3-H-leucine 3 H-hGH is obtained in the medium giving evidence of hormone synthesis by adenoma cells in culture. 3-H-hGH represents 40 percent of 3-H-proteins in the culture medium and gives the same elution pattern as standard hGH on Sephadex G 100 chromatography. A certain degree of correlation is observed between morphological and biological results: the greatest hGH production is obtained from explants which maintain the best histological appearance.

Acromegaly↗