Effect of Estrogen on Prolactin mRNA in the Rat Pituitary

Yamamoto, Naohiho; Seo, Hisao; Suganuma, Nobuhiko; Matsui, Nobuo; Nakane, Tohichi; Kuwayama, Akio; Kageyama, Naoki

doi:10.1159/000124493

Cited by 30 publications

(4 citation statements)

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“…In our experimental conditions, these variants were not detected in normal pituitaries where the rate of prolactin synthesis was low. Therefore, our data provided confirmation of the effect of oestrogens in vivo on the synthesis of prolactin by acting at the translation level (Yamamoto, Seo, Suganuma et al 1986). Pituitary prolactin content remained constant because the increase in synthesis was balanced by the increase in release.…”

Section: Discussionsupporting

confidence: 75%

Concanavalin-A-bound and -unbound prolactin in normal and hyperprolactinaemic rats

Champier¹,

Bruno²,

Harthé³

et al. 1992

Journal of Endocrinology

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Concanavalin-A (Con-A)-bound and -unbound forms of prolactin were studied in female Wistar-Furth rats, both normal and with hyperprolactinaemia induced by treatment with oestrogen or a prolactinoma graft. In normal rats, Con-A-bound prolactin was the major circulating form (more than 50%) and a minor pituitary component (less than 10%), essentially as 25 kDa prolactin. In oestrogen-treated rats, plasma prolactin levels were 100-fold higher and pituitary weight was fivefold higher than in the controls, but total pituitary prolactin content was unmodified. Under oestrogen, Con-A-bound prolactin represented about one-third of the total hormone levels in the plasma and less than 10% in the pituitary. In the pituitary, bound prolactin was found essentially as 25 kDa and unbound prolactin as 22, 30 and 40-45 kDa. A similar increase in plasma prolactin levels was induced 6 months after the graft of a prolactinoma. Pituitary weights and total pituitary prolactin contents were slightly decreased. Plasma and pituitary Con-A-bound prolactin levels were similar to those observed in oestrogen-treated rats. On the other hand, unbound prolactin was only present as a 22 kDa monomer. In the tumour, Con-A-bound prolactin (essentially as 25 kDa prolactin) represented one-third of the total hormone level and unbound prolactin was composed of the 22 and 45 kDa forms, this latter form being partially transformed into 22 kDa by heating.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionsupporting

confidence: 75%

Concanavalin-A-bound and -unbound prolactin in normal and hyperprolactinaemic rats

Champier¹,

Bruno²,

Harthé³

et al. 1992

Journal of Endocrinology

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“…Estrogen treatment stimulates both pituitary PRL content and plasma PRL levels in mature male or female rats (Nogami, 1984) and in ovariectomized female rats (Chen and Meites, 1970). In addition, E, also exerts effects on rat PRL gene transcription with a stimulation of PRL mRNA synthesis in the adult rat (Maurer, 1982;Yamamoto et al, 1986). No such effects were observed in the present .study, in which E, did not modify the various PRL parameters analyzed in mature or immature rainbow trout: our results then suggest a lack of regulation of PRL cells by estrogens in this fish species.…”

Section: Discussionsupporting

confidence: 40%

Absence of direct regulation of prolactin cells by estradiol-17β in rainbow trout (Oncorhynchus mykiss)

Goff

Salbert

Prunet

et al. 1992

Molecular and Cellular Endocrinology

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SummaryThe effects of estradiol-17/3 (E,) implants on plasma prolactin (PRL) concentrations, pituitary PRL content and pituitary PRL mRNA levels were examined in rainbow trout (Oncorhynchus mykiss). Intact immature fish treated with 1 mg estradiol-17/? did not show significant changes in both PRL mRNA levels and pituitary PRL content after 3 days of treatment. In a similar experiment, no changes were observed in plasma PRL levels followed during 7 days. Similarly, lack of estradiol-17/3 effect on plasma PRL levels and on final PRL pituitary content was observed in ovariectomized female rainbow trout treated during 48 days with 25 mg estradiol-17P and in mature male fish over a 3-week treatment period. Localization of estradiol receptor (ER) mRNAs in the pituitary was carried out by Northern blot analysis using a full-length rainbow trout estrogen receptor (rtER) cDNA as a probe. The rostra1 pars distalis of the pituitary which contained mostly PRL cells showed the lower amount of rtER mRNA when compared to other parts of the pituitary. Moreover, two mRNAs of different size (3.5 and 1.4 kb) were detected in different parts of the pituitary. Further hybridization experiments using probes containing part of the rtER cDNA (E domain or C and D domains) indicated that the small-sized mRNA (1.4 kb) probably encodes a truncated ER protein lacking hormone binding domain or an ER-related protein. Thus, only the 3.56 kb mRNA appeared to be involved in the regulation of pituitary function by estradiol. In situ hybridization analysis allowed a more precise localization of this rtER mRNA in the pituitary. No labeling was discernible over PRL cells whereas other parts of the pituitary were labeled. Grain counting corroborated this localization. These results indicate that (1) in vivo estradiol-17P treatment did not modify PRL cell activity in rainbow trout, (2) PRL secretion, in this fish species, is not directly regulated by estradiol.

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“…Furthermore, estradiol induces the proliferation of pituitary prolactin-producing cells [20], [54]–[58].…”

Section: Discussionmentioning

confidence: 99%

Local Transformations of Androgens into Estradiol by Aromatase P450 Is Involved in the Regulation of Prolactin and the Proliferation of Pituitary Prolactin-Positive Cells

et al. 2014

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In previous studies we demonstrated the immunohistochemical expression of aromatase in pituitary cells. In order to determine whether pituitary aromatase is involved in the paracrine regulation of prolactin-producing pituitary cells and the physiological relevance of pituitary aromatase in the control of these cells, an in vivo and in vitro immunocytochemical and morphometric study of prolactin-positive pituitary cells was carried out on the pituitary glands of adult male rats treated with the aromatase antagonist fadrozole. Moreover, we analyzed the expression of mRNA for the enzyme in pituitary cells of male adult rats by in situ hybridization. The aromatase-mRNA was seen to be located in the cytoplasm of 41% of pituitary cells and was well correlated with the immunocytochemical staining. After in vivo treatment with fadrozole, the size (cellular and nuclear areas) of prolactin cells, as well as the percentage of prolactin-positive cells and the percentage of proliferating-prolactin cells, was significantly decreased. Moreover, fadrozole decreased serum prolactin levels. In vitro, treatment with fadrozole plus testosterone induced similar effects on prolactin-positive cells, inhibiting their cellular proliferation. Our results suggest that under physiological conditions aromatase P450 exerts a relevant control over male pituitary prolactin-cells, probably transforming testosterone to estradiol in the pituitary gland.

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Effect of Estrogen on Prolactin mRNA in the Rat Pituitary

Cited by 30 publications

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Concanavalin-A-bound and -unbound prolactin in normal and hyperprolactinaemic rats

Concanavalin-A-bound and -unbound prolactin in normal and hyperprolactinaemic rats

Absence of direct regulation of prolactin cells by estradiol-17β in rainbow trout (Oncorhynchus mykiss)

Local Transformations of Androgens into Estradiol by Aromatase P450 Is Involved in the Regulation of Prolactin and the Proliferation of Pituitary Prolactin-Positive Cells

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