Release of Anterior Pituitary Hormones by Trypsin-pretreated Anterior Pituitary Cells

Abstract Ghrelin is the endogenous ligand for the GH secretagogue receptor (GHSR) and robustly stimulates GH release from the anterior pituitary gland. Ghrelin also regulates the secretion of anterior pituitary hormones including TSH, LH, prolactin (PRL), and ACTH. However, the relative contribution of a direct action at the GHSR in the anterior pituitary gland vs. an indirect action at the GHSR in the hypothalamus remains undefined. We used a novel GHSR-enhanced green fluorescent protein (eGFP) reporter mouse to quantify GHSR coexpression with GH, TSH, LH, PRL, and ACTH anterior pituitary cells in males vs. females and in chow-fed or calorie-restricted (CR) mice. GHSR-eGFP-expressing cells were only observed in anterior pituitary. The number of GHSR-eGFP-expressing cells was higher in male compared with females, and CR did not affect the GHSR-eGFP cell number. Double staining revealed 77% of somatotrophs expressed GHSR-eGFP in both males and females. Nineteen percent and 12.6% of corticotrophs, 21% and 9% of lactotrophs, 18% and 19% of gonadotrophs, and 3% and 9% of males and females, respectively, expressed GHSR-eGFP. CR increased the number of TSH cells, but suppressed the number of lactotrophs and gonadotrophs, expressing GHSR-eGFP compared with controls. These studies support a robust stimulatory action of ghrelin via the GHSR on GH secretion and identify a previously unknown sexual dimorphism in the GHSR expression in the anterior pituitary. CR affects GHSR-eGFP expression on lactotrophs, gonadotrophs, and thyrotrophs, which may mediate reproductive function and energy metabolism during periods of negative energy balance. The low to moderate expression of GHSR-eGFP suggests that ghrelin plays a minor direct role on remaining anterior pituitary cells.

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Arachidonate 12-lipoxygenase in porcine anterior pituitary cells: its localization and possible function in gonadotrophs

Journal of Endocrinology ◽

10.1677/joe.0.1480033 ◽

1996 ◽

Vol 148 (1) ◽

pp. 33-41 ◽

Cited By ~ 8

Author(s):

H Ikawa ◽

K Yamamoto ◽

Y Takahashi ◽

N Ueda ◽

Y Hayashi ◽

...

Keyword(s):

Anterior Pituitary ◽

Nordihydroguaiaretic Acid ◽

Pituitary Hormones ◽

Pituitary Hormone ◽

Pituitary Cells ◽

Dependent Manner ◽

Lipoxygenase Inhibitor ◽

Anterior Pituitary Cells ◽

Significant Stimulation ◽

12 Lipoxygenase

Abstract Arachidonate 12-lipoxygenase, which oxygenates positions 12 and 13 of arachidonic and linoleic acids, is present in porcine anterior pituitary cells. Colocalization of the 12-lipoxygenase with various pituitary hormones was examined by immunohistochemical double-staining using antibodies against 12-lipoxygenase and various anterior pituitary hormones. Under light microscopy, approximately 7% of the cells producing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were positive for 12-lipoxygenase, whereas the enzyme was detected in less than 2% of the cells producing thyrotrophin, prolactin, growth hormone (GH), and adrenocorticotrophin. In an attempt to examine the participation of 12-lipoxygenase metabolites in pituitary hormone release, we incubated the primary culture of porcine anterior pituitary cells with 12-hydroperoxy-arachidonic acid or 13-hydroperoxy-linoleic acid. Significant stimulation of LH and FSH release by these hydroperoxides was observed at 10 μm in a time-dependent manner. At doses around 10 μm these compounds produced responses of similar magnitude to 1 nm gonadotrophin-releasing hormone (GnRH), but higher concentrations (30 μm) of the compounds were required for GH release. In contrast, 12-hydroxy-arachidonic and 13-hydroxy-linoleic acids were almost ineffective. Furthermore, the gonadotrophin release by 1 nm GnRH was inhibited by nordihydroguaiaretic acid (a lipoxygenase inhibitor) with an IC50 of about 5 μm. Thus, the hydroperoxy (but not hydroxy) products of 12-lipoxygenase may be involved in the release of pituitary hormones especially LH and FSH. Journal of Endocrinology (1996) 148, 33–41

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Ultrastructural morphology of nontumorous lactotrophs in human pituitaries exposed to high prolactin levels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128766 ◽

1987 ◽

Vol 45 ◽

pp. 896-897

Author(s):

S. Jalalah ◽

K. Kovacs ◽

E. Horvath

Keyword(s):

Anterior Pituitary ◽

Secretory Activity ◽

Pituitary Hormones ◽

Feedback Mechanism ◽

Endocrine Activity ◽

Hormone Synthesis ◽

Anterior Pituitary Hormones ◽

Negative Feedback Mechanism ◽

Ultrastructural Morphology ◽

Transmission Electron

Lactotrophs, as many other endocrine cells, change their morphology in response to factors influencing their secretory activity. Secretion of prolactin (PRL) from lactotrophs, like that of other anterior pituitary hormones, is under the control of the hypothalamus. Unlike most anterior pituitary hormones, PRL has no apparent target gland which could modulate the endocrine activity of lactotrophs. It is generally agreed that PRL regulates its own release from lactotrophs via the short loop negative feedback mechanism exerted at the level of the hypothalamus or the pituitary. Accordingly, ultrastructural morphology of lactotrophs is not constant; it is changing in response to high PRL levels showing signs of suppressed hormone synthesis and secretion.By transmission electron microscopy and morphometry, we have studied the morphology of lactotrophs in nontumorous (NT) portions of 7 human pituitaries containing PRL-secreting adenoma; these lactotrophs were exposed to abnormally high PRL levels.

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Evaluation of estrogen effects on the anterior pituitary hormones by using combined pituitary stimulation test (CPFT) in the Korean postmenopausal women

Endocrine Abstracts ◽

10.1530/endoabs.49.ep950 ◽

2017 ◽

Author(s):

Sung-Woon Kim ◽

Seungjoon Oh

Keyword(s):

Postmenopausal Women ◽

Anterior Pituitary ◽

Pituitary Hormones ◽

Stimulation Test ◽

Anterior Pituitary Hormones ◽

Estrogen Effects

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Proceedings: initiation of implantation in the mouse with anterior pituitary hormones

Reproduction ◽

10.1530/jrf.0.0430387 ◽

1975 ◽

Vol 43 (2) ◽

pp. 387-388 ◽

Cited By ~ 1

Author(s):

A. Gidley-Baird

Keyword(s):

Anterior Pituitary ◽

Pituitary Hormones ◽

Anterior Pituitary Hormones

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Estrogen mediates sex differences in preoptic neuropeptide and pituitary hormone production in medaka

Communications Biology ◽

10.1038/s42003-021-02476-5 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Junpei Yamashita ◽

Yuji Nishiike ◽

Thomas Fleming ◽

Daichi Kayo ◽

Kataaki Okubo

Keyword(s):

Anterior Pituitary ◽

Pituitary Hormones ◽

Pituitary Hormone ◽

Sexually Dimorphic ◽

Hormone Production ◽

Anterior Pituitary Hormones ◽

Vertebrate Brain ◽

Pituitary Adenylate Cyclase ◽

Evolutionarily Conserved ◽

Sexually Dimorphic Expression

AbstractThe preoptic area (POA) is one of the most evolutionarily conserved regions of the vertebrate brain and contains subsets of neuropeptide-expressing neurons. Here we found in the teleost medaka that two neuropeptides belonging to the secretin family, pituitary adenylate cyclase-activating polypeptide (Pacap) and vasoactive intestinal peptide (Vip), exhibit opposite patterns of sexually dimorphic expression in the same population of POA neurons that project to the anterior pituitary: Pacap is male-biased, whereas Vip is female-biased. Estrogen secreted by the ovary in adulthood was found to attenuate Pacap expression and, conversely, stimulate Vip expression in the female POA, thereby establishing and maintaining their opposite sexual dimorphism. Pituitary organ culture experiments demonstrated that both Pacap and Vip can markedly alter the expression of various anterior pituitary hormones. Collectively, these findings show that males and females use alternative preoptic neuropeptides to regulate anterior pituitary hormones as a result of their different estrogen milieu.

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