Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Resistance to bromocriptine, defined as the absence of normalization of prolactin (PRL) levels despite a 15-30 mg daily dose of bromocriptine during at least 6 months, has been observed in 5-17% of the prolactinomas according to the literature. The recent availability of a new potent dopamine agonist, quinagolide, prompted us to analyze its long-term therapeutic effects in 28 patients with prolactinomas resistant to bromocriptine. Before bromocriptine, their PRL levels were 520 +/- 185 micrograms/l (mean +/- SEM) and decreased to 291 +/- 154 micrograms/l after a 6-21 month period of bromocriptine treatment. All the women (N = 20) remained amenorrheic and hypogonadism was not improved in men (N = 8). Subsequently, after 1 year of 150-300 micrograms/day quinagolide, 12/28 patients of the present series recovered normal gonadal function and their initial mean baseline PRL value (404 +/- 180 micrograms/l) was 16 +/- 2 micrograms/l after 1 year of treatment. A significant tumor shrinkage was observed in 5/8 macroadenomas (62%). During the 3-year follow-up period under quinagolide, a similar good control was achieved in these patients, with the exception of one man presenting with a secondary rise of PRL under quinagolide. In contrast, 15 other patients (one patient interrupted quinagolide at 6 months because of poor tolerance) were not normalized under 150-450 micrograms/day quinagolide. Their initial PRL levels (606 +/- 298 micrograms/l) were reduced to 343 +/- 187 micrograms/l (versus 463 +/- 265 micrograms/l under bromocriptine after the same duration of treatment). Despite such a partial inhibitory effect of quinagolide, 7/12 women resumed menstrual cycles and three pregnancies occurred. In no case was any tumor shrinkage noticed during the 3-4-year follow-up. Three patients even presented, after 2 years of quinagolide treatment, with a secondary rise of PRL values associated with a further tumor growth in two patients. During the 3-year follow-up period, nine pregnancies occurred in seven women. In five women, after quinagolide withdrawal, the plasma PRL baseline values ranged from 52 to 158 micrograms/l and from 65 to 192 micrograms/l, respectively, at the first trimester and at the end of uneventful pregnancies. In contrast, in two women a rapid increase of PRL (240-400 micrograms/l) correlated with tumor growth during the first trimester. Such a tumor progression was blocked by quinagolide treatment but not by bromocriptine. These data, although observed in a limited series, justify the careful follow-up of pregnancies in this subclass of patients at risk. Finally, in the whole population, long-term control of hyperprolactinemia by quinagolide was obtained in 11/28 patients (39%) previously resistant to bromocriptine, and 15/20 women (75%) resumed normal gonadal function with a quinagolide daily dose of 300 micrograms in most of them.
 ...
PMID:Prolactinomas resistant to bromocriptine: long-term efficacy of quinagolide and outcome of pregnancy. 892 22

We have previously reported that the hyperprolactinemia in incubating turkey hens is associated with recruitment of lactotrophs in the pituitary gland. In this study we have used double immunofluorescence and in situ hybridization histochemistry to 1) identify mammosomatotrophs in the anterior pituitary gland of egg-laying turkey hens and incubating hens, and 2) verify PRL gene expression within mammosomatotrophs by colocalizing PRL messenger RNA in GH-immunoreactive (ir) cells. The pituitaries of laying and incubating turkey hens were collected, and the midsagittal sections were dual labeled for either PRL and GH or PRL messenger RNA and GH. The plasma PRL concentrations were higher in incubating hens (231 +/- 10.6 ng/ml) than in laying hens (43 +/- 7.4 ng/ml; P < 0.01). In the midsagittal pituitary sections, mammosomatotrophs were predominantly found scattered in the caudal lobe of the anterior pituitary gland, in the ventral half of the cephalic lobe, and at the junction of cephalic and caudal lobes. In incubating hens, the proportion of mammosomatotrophs was 7.4 +/- 1.52% (mean +/- SEM) of the total number of GH-ir and/or PRL-ir cells counted, which was significantly higher (P < 0.05) than that found in laying hens (0.6 +/- 0.23%). Furthermore, PRL gene expression was observed in many GH-ir cells in the incubating hen pituitary gland. These data suggest that 1) mammosomatotrophs are present in the turkey pituitary gland, and 2) there is an increased abundance of mammosomatotrophs in the incubating turkey hen that may contribute to hyperprolactinemia.
 ...
PMID:Identification of mammosomatotrophs in the turkey hen pituitary: increased abundance during hyperprolactinemia. 944 53

Liver cirrhosis, a highly prevalent chronic disease, is frequently associated with endocrine dysfunctions, notably in the gonadal axis. We evaluated lactotroph population by immunohistochemistry, gonadotropins and prolactin by immunoradiometric assay and testosterone and estradiol by radioimmunoassay in adult male Wistar rats with cirrhosis induced by carbon tetrachloride. No significant difference in mean +/- SEM percentages of lactotrophs was found between cirrhotic animals and controls (N = 12, mean 18.95 +/- 1.29%). Although there was no significant difference between groups in mean serum levels of prolactin (control: 19.2 +/- 4 ng/mL), luteinizing hormone (control: 1.58 +/- 0.43 ng/mL), follicle-stimulating hormone (control: 19.11 +/- 2.28 ng/mL), estradiol (control: 14.65 +/- 3.22 pg/mL), and total testosterone (control: 138.41 +/- 20.07 ng/dL), 5 of the cirrhotic animals presented a hormonal profile consistent with hypogonadism, all of them pointing to a central origin of this dysfunction. Four of these animals presented high levels of estradiol and/or prolactin, with a significant correlation between these two hormones in both groups (r = 0.54; P = 0.013). It was possible to detect the presence of central hypogonadism in this model of cirrhotic animals. The hyperestrogenemia and hyperprolactinemia found in some hypogonadal animals suggest a role in the genesis of hypogonadism, and in the present study they were not associated with lactotroph hyperplasia.
 ...
PMID:Male gonadal function, prolactin secretion and lactotroph population in an experimental model of cirrhosis. 1771 59


<< Previous 1 2 3 4 5