Chronic effect of antidopaminergic drugs or estrogen on male Wistar rat lactotrophs and somatotrophs

Oliveira, Miriam C.; Messinger, Horst; Tannhauser, Mário; Barbosa-Coutinho, Lígia Maria

doi:10.1590/s0100-879x1999001200018

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…The percentage of lactotrophs found in the control group was within the range previously reported for adult male Wistar rats, i.e., 10.5% (26), 15% (27), 21.7% (28), and 26% (29).…”

Section: Discussionsupporting

confidence: 87%

Male gonadal function, prolactin secretion and lactotroph population in an experimental model of cirrhosis

Gonzáles

Rhoden

Luz

et al. 2007

Braz J Med Biol Res

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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.

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“…The percentage of lactotrophs found in the control group was within the range previously reported for adult male Wistar rats, i.e., 10.5% (26), 15% (27), 21.7% (28), and 26% (29).…”

Section: Discussionsupporting

confidence: 87%

Male gonadal function, prolactin secretion and lactotroph population in an experimental model of cirrhosis

Gonzáles

Rhoden

Luz

et al. 2007

Braz J Med Biol Res

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“…Immunohistochemistry, however, may reveal increased or decreased lactotroph immunoreactivity for prolactin (Spritzer et al, 1996;Oliveira et al, 1999). In estrogen-stimulated rats treated with bromocriptine, a decreased labeling index for the proliferating cell nuclear antigen and increased apoptotic nuclei correlated with hypoprolactinemia, indicating reduced cellular proliferation and increased cell death (Yonezawa et al, 1997).…”

Section: Effect On Pituitary Weight or Histomorphologymentioning

confidence: 99%

Identification of drug‐induced hyper‐ or hypoprolactinemia in the female rat based on general and reproductive toxicity study parameters

Rehm¹,

Stanislaus²,

Wier³

2007

Birth Defects Research Pt B

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Observations associated with drug-induced hyper- or hypoprolactinemia in rat toxicology studies may be similar and include increased ovarian weight due to increased presence of corpora lutea. Hyperprolactinemia may be distinguished if mammary gland hyperplasia with secretion and/or vaginal mucification is observed. Reproductive toxicity study endpoints can differentiate hyper- from hypoprolactinemia based on their differential effects on estrous cycles, mating, and fertility. Although the manifestations of hyper- and hypoprolactinemia in rats generally differ from that in humans, mechanisms of drug-related changes in prolactin synthesis/release can be conserved across species and pathologically increased or decreased prolactin levels may compromise some aspect of reproductive function in all species.

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“…It has been demonstrated that estrogens act on the biosynthesis and secretion of all hormones of the anterior pituitary and stimulate the proliferation of lactotropes and gonadotropes [1, 2, 3, 4, 5, 6, 7, 8]. The physiological effects of estrogen on the pituitary gland, including cellular proliferation and hormone synthesis regulation, are mediated by the nuclear estrogen receptor (ER), which exhibits two separate but related forms: ERα and ERβ, with different patterns of expression in tissues and cells.…”

Section: Introductionmentioning

confidence: 99%

Immunohistochemical Detection of Estrogen Receptor Alpha in Pituitary Adenomas and Its Correlation with Cellular Replication

et al. 2004

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With the aim of evaluating the relationship between pituitary tumorigenesis and the presence of estrogen receptor-α (ERα) by immunohistochemistry (IH) and their relevance to patients’ clinical presentation, hormonal phenotypes of adenomas, preoperative neuroimaging findings, and the index of cellular replication MIB-1, a study was conducted with material from 91 women and 67 men with pituitary adenomas. The patients had acromegaly (29.7%), Cushing’s disease (14.6%), hyperprolactinemic syndrome (20.9%), and clinically nonfunctioning tumors (34.8%). Of the patients, 14.6% had microadenomas, 52.5% had macroadenomas with or without suprasellar growth, 28.5% had invasive macroadenomas and in 4.4% the adenoma was not visualized. IH showed that 43 were positive for growth hormone (GH), 16 for corticotropin (ACTH), 18 for prolactin (PRL), 18 for PRL+GH, 6 for luteinizing hormone (LH) and follicle-stimulating hormone (FSH), 15 had a plurihormonal reaction, and 42 had nonfunctioning adenomas. The presence of ERα was positive in 9/158 adenomas with a median value for the percentage of labeled cells of 42.89%, and in 6/16 controls (autopsy samples) with a median value for the percentage of labeled cells of 0.024%. ERα was significantly more prevalent in controls than in patients with adenomas (37.5 versus5.7%; p = 0.001); however, the mean ERα concentration in adenomas was significantly greater than in controls (42.89 versus 0.024%; p < 0.001). No significant difference in the concentration of ERα was found across the clinical presentations, hormonal phenotypes or findings of preoperative CT. Among the ERα-positive adenomas, ERα values were significantly greater in invasive macroadenomas (80%) than in microadenomas (3.33%). MIB-1 values did not differ significantly between ERα-positive and -negative adenomas, nor did the correlation between ERα values and the MIB-1 index attain significance in the total sample, even when only ERα-positive adenomas and positive MIB-1 indexes were considered. It was concluded that, when present in pituitary tumors, ERα exhibits a high concentration, and is more common in nonfunctioning and invasive adenomas, but absent in ACTH-secreting ones.

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Chronic effect of antidopaminergic drugs or estrogen on male Wistar rat lactotrophs and somatotrophs

Cited by 5 publications

References 9 publications

Male gonadal function, prolactin secretion and lactotroph population in an experimental model of cirrhosis

Male gonadal function, prolactin secretion and lactotroph population in an experimental model of cirrhosis

Identification of drug‐induced hyper‐ or hypoprolactinemia in the female rat based on general and reproductive toxicity study parameters

Immunohistochemical Detection of Estrogen Receptor Alpha in Pituitary Adenomas and Its Correlation with Cellular Replication

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