Functional Lactotrophs in Induced Adenohypophysis Differentiated From Human iPS Cells

Prolactin (PRL), a hormone involved in lactation, is mainly produced and secreted by the lactotrophs of the anterior pituitary (AP) gland. We previously reported a method to generate functional adrenocorticotropic hormone-producing cells by differentiating the AP and hypothalamus simultaneously from human induced pluripotent stem cells (iPSCs). However, PRL-producing cells in the induced AP have not been investigated. Here, we confirmed the presence of PRL-producing cells and evaluated their endocrine functions. We differentiated pituitary cells from human iPSCs using serum-free floating culture of embryoid-like aggregates with quick reaggregation (SFEB-q) method and evaluated the appearance and function of PRL-producing cells. Secretion of PRL from the differentiated aggregates was confirmed, which increased with further culture. Fluorescence immunostaining and immunoelectron microscopy revealed PRL-producing cells and PRL-positive secretory granules, respectively. PRL secretion was promoted by various prolactin secretagogues such as thyrotropin-releasing hormone, vasoactive intestinal peptide, and prolactin-releasing peptide, and inhibited by bromocriptine. Moreover, the presence of tyrosine hydroxylase-positive dopaminergic nerves in the hypothalamic tissue area around the center of the aggregates connecting to PRL-producing cells indicated the possibility of recapitulating PRL regulatory mechanisms through the hypothalamus. In conclusion, we generated pituitary lactotrophs from human iPSCs; these displayed similar secretory responsiveness as human pituitary cells in vivo. In the future, this is expected to be used as a model of human PRL-producing cells for various studies, such as drug discovery, prediction of side effects, and elucidation of tumorigenic mechanisms using disease-specific iPSCs. Furthermore, it may help to develop regenerative medicine for the pituitary gland.

Influence of the expression vector and its elements on recombinant human prolactin synthesis in Escherichia coli; co-directional orientation of replication and transcription is highly critical

The aim of the present work was to define a bacterial expression system that is particularly efficient for the synthesis of recombinant human prolactin (hPRL). In previous work, based on experiments that were basically carried out in parallel with the present ones, the synthesis of rec-hPRL by the p1813-hPRL vector in E. coli HB2151 was >500 mg/L, while it was much lower here (2.5-4-fold), in the RB791 and RRI strains. The highest positive influence on rec-hPRL synthesis was due to the transcription-replication co-orientation of hPRL cDNA and the ori/antibiotic resistance gene, responsible for up to a ~ 5-6-fold higher expression yield. In conclusion, this work confirmed that each bacterial strain of E. coli has a genetic background that can allow a different level of heterologous protein synthesis. The individual study of each element indicated that its action critically depends on the reading orientation in which it is located inside the vector: co-directional orientation of replication and transcription, in fact, greatly increased the level of rec-hPRL expression.

miR-375 acts as a novel factor modulating pituitary prolactin synthesis through Rasd1 and Esr1

Prolactin (PRL) is a pituitary hormone that regulates multiple physiological processes. However, the mechanisms of PRL synthesis have not been fully elucidated. The aims of the present study were to study the functions and the related mechanisms of miR-375 regulating PRL synthesis. We initially found that miR-375 mainly expressed in the lactotrophs of mouse pituitary gland. To identify the function of miR-375 in the pituitary gland, the miR-375 knockout mice were generated by using Crispr/Cas9 technique. The results showed that miR-375 knockout resulted in the decline of pituitary PRL mRNA and protein levels by 75.7 and 60.4%, respectively, and the serum PRL level reduced about 46.1%, but had no significant effect on FSH, LH and TSH. Further, we identified that Estrogen receptor 1 (alpha) (Esr1) was a downstream molecule of miR-375. The real-time PCR and Western blot results showed that ESR1 mRNA and protein levels markedly decreased by 40.9 and 42.9% in the miR-375 knockout mouse pituitary, and these were subsequently confirmed by the in vitro study using transfections of miR-375 mimics and inhibitors in pituitary lactotroph GH4 cells. Further, Rasd1 was predicted by bioinformatic tools and proved to be the direct target of miR-375 in lactotrophs using the dual-luciferase reporter assay. Rasd1-siRNA transfection results revealed the negative effect of Rasd1 in regulating ESR1. Collectively, the results presented here demonstrate that miR-375 positively modulates PRL synthesis through Rasd1 and Esr1, which are crucial for understanding the regulating mechanisms of pituitary hormone synthesis.

Effect of Hordei Fructus Germinatus on differential gene expression in the prolactin signaling pathway in the mammary gland of lactating rats

ETHNOPHARMACOLOGICAL RELEVANCE

In China, Hordei Fructus Germinatus (HFG) is the germinated and dried fruit of Hordeum vulgare L, which is commonly used in clinical Chinese medicine. Traditional Chinese Medicine (TCM) theory holds that HFG can be both medicinal and edible, which means that it is derived from food medicine. Raw HFG and roasted HFG are used to treat hypogalactia, hyperprolactinemia and indigestion. In recent years, the lactogenic and galactophygous effects of HFG have attracted increasing attention. Nevertheless, there is much confusion over the use of raw and processed HFG, and the mechanism of its lactogenic effect seems remains poorly understood.

AIM OF THE STUDY

This study aimed to explore the lactogenic effect of raw HFG and roasted HFG on rats with overloaded lactation and to reveal the underlying molecular mechanism.

MATERIALS AND METHODS

Raw and processed HFG water decoctions were given to overloaded lactation model rats at a dose of 1.7800 g kg^-1·d^-1, and the control group was given the same volume of water. The lactogenic effect of raw and processed HFG was evaluated by measuring daily lactation, body weight and pup body weight, serum PRL, E2, and GH contents after parturition, and the pathological characteristics of mammary tissue sections. cDNA microarrays can be used to screen diverse gene expression patterns and signaling pathways related to prolactin. The expression of relevant differentially expressed genes was verified by real-time PCR and western blotting.

RESULTS

In vivo experiments demonstrated that the raw HFG water decoction stimulated mammogenesis, accelerated the transformation of the lobular acinar system, resulted in denser mammary epithelial cells and thicker glandular ducts that were full of milk and facilitated the secretion of milk. Moreover, HFG increased PRL, E2, and GH levels, pup body weight, daily lactation and the body weight of lactating rats. Following gene chip identification, KEGG pathway enrichment analysis revealed genes that were highly related to prolactin in the prolactin signaling pathway and JAK-STAT signaling pathway, and the main differentially expressed genes were Jak2 (down), Stat5α (up), cyclin D1 (up), SOCS1 (up), CISH (down) and PRLR (up). Compared with the control group, RT-PCR results indicated that Jak2 and CISH were downregulated and that Stat5α, cyclin D1, SOCS1 and PRLR were upregulated. Western blot assays showed that PRLR, STAT5α and cyclin D1 levels in the mammary glands of the raw HFG water decoction group were significantly increased, which was consistent with the results of cDNA microarray screening.

CONCLUSION

The present study reveals that raw HFG effectively enhances lactation in rats, possibly by influencing the prolactin/JAK-STAT signaling pathway.

Calcium-Prolactin Secretion Coupling in Rat Pituitary Lactotrophs Is Controlled by PI4-Kinase Alpha

The role of calcium, but not of other intracellular signaling molecules, in the release of pituitary hormones by exocytosis is well established. Here, we analyzed the contribution of phosphatidylinositol kinases (PIKs) to calcium-driven prolactin (PRL) release in pituitary lactotrophs: PI4Ks - which control PI4P production, PIP5Ks - which synthesize PI(4, 5)P2 by phosphorylating the D-5 position of the inositol ring of PI4P, and PI3KCs - which phosphorylate PI(4, 5)P₂ to generate PI(3, 4, 5)P₃. We used common and PIK-specific inhibitors to evaluate the strength of calcium-secretion coupling in rat lactotrophs. Gene expression was analyzed by single-cell RNA sequencing and qRT-PCR analysis; intracellular and released hormones were assessed by radioimmunoassay and ELISA; and single-cell calcium signaling was recorded by Fura 2 imaging. Single-cell RNA sequencing revealed the expression of Pi4ka, Pi4kb, Pi4k2a, Pi4k2b, Pip5k1a, Pip5k1c, and Pik3ca, as well as Pikfyve and Pip4k2c, in lactotrophs. Wortmannin, a PI3K and PI4K inhibitor, but not LY294002, a PI3K inhibitor, blocked spontaneous action potential driven PRL release with a half-time of ~20 min when applied in 10 µM concentration, leading to accumulation of intracellular PRL content. Wortmannin also inhibited increase in PRL release by high potassium, the calcium channel agonist Bay K8644, and calcium mobilizing thyrotropin-releasing hormone without affecting accompanying calcium signaling. GSK-A1, a specific inhibitor of PI4KA, also inhibited calcium-driven PRL secretion without affecting calcium signaling and Prl expression. In contrast, PIK93, a specific inhibitor of PI4KB, and ISA2011B and UNC3230, specific inhibitors of PIP5K1A and PIP5K1C, respectively, did not affect PRL release. These experiments revealed a key role of PI4KA in calcium-secretion coupling in pituitary lactotrophs downstream of voltage-gated and PI(4, 5)P2-dependent calcium signaling.

Transcriptional regulation of prolactin in a euryhaline teleost: Characterisation of gene promoters through in silico and transcriptome analyses

The sensitivity of prolactin (Prl) cells of the Mozambique tilapia (Oreochromis mossambicus) pituitary to variations in extracellular osmolality enables investigations into how osmoreception underlies patterns of hormone secretion. Through the actions of their main secretory products, Prl cells play a key role in supporting hydromineral balance of fishes by controlling the major osmoregulatory organs (ie, gill, intestine and kidney). The release of Prl from isolated cells of the rostral pars distalis (RPD) occurs in direct response to physiologically relevant reductions in extracellular osmolality. Although the particular signal transduction pathways that link osmotic conditions to Prl secretion have been identified, the processes that underlie hyposmotic induction of prl gene expression remain unknown. In this short review, we describe two distinct tilapia gene loci that encode Prl177 and Prl188 . From our in silico analyses of prl177 and prl188 promoter regions (approximately 1000 bp) and a transcriptome analysis of RPDs from fresh water (FW)- and seawater (SW)-acclimated tilapia, we propose a working model for how multiple transcription factors link osmoreceptive processes with adaptive patterns of prl177 and prl188 gene expression. We confirmed via RNA-sequencing and a quantitative polymerase chain reaction that multiple transcription factors emerging as predicted regulators of prl gene expression are expressed in the RPD of tilapia. In particular, gene transcripts encoding pou1f1, stat3, creb3l1, pbxip1a and stat1a were highly expressed; creb3l1, pbxip1a and stat1a were elevated in fish acclimated to SW vs FW. Combined, our in silico and transcriptome analyses set a path for resolving how adaptive patterns of Prl secretion are achieved via the integration of osmoreceptive processes with the control of prl gene transcription.

The ancient Chinese formula Longdan Xiegan Tang improves antipsychotic-induced hyperprolactinemia by repairing the hypothalamic and pituitary TGF-β1 signaling in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Antipsychotics often induce hyperprolactinemia. The transforming growth factor (TGF)-beta1 signaling in the pituitary and hypothalamus inhibits prolactin synthesis and secretion, and its impairment is implicated in neuropsychiatric disorders. Longdan Xiegan Tang (LXT) alone or together with antipsychotics have been used to treat various neuropsychiatric diseases and hyperprolactinemia-associated disorders.

AIM OF THE STUDY

To investigate the effect of LXT on hyperprolactinemia and involvement of the TGF-beta1 signaling.

MATERIALS AND METHODS

Male rats were co-administered with olanzapine (5 mg/kg) and LXT extract (50 and 500 mg/kg) (p.o., × 8 weeks). Plasma concentrations of prolactin and TGF-beta1 were determined by ELISA. Protein expression was analyzed by Western blot.

RESULTS

Treatment of rats with LXT extract suppressed olanzapine-induced increase in plasma prolactin concentration and overexpression of pituitary and hypothalamic prolactin protein. Importantly, LXT restored olanzapine-induced decrease in protein expression of the key components of the TGF-beta1 signaling, TGF-beta1, type II TGF-beta receptor, type I TGF-beta receptor and phosphorylated SMAD3 in the pituitary and hypothalamus. Further, it antagonized downregulation of pituitary and hypothalamic dopamine D2 receptor (D2R) protein level, and inhibited pituitary estrogen receptor (ER) alpha and ERbeta protein expression.

CONCLUSIONS

The present results suggest that LXT ameliorates antipsychotic-induced hyperprolactinemia in rats by repairing the pituitary and hypothalamic TGF-beta1 signaling possibly via D2R, ERs or/and other pathways. Our findings may also provide scientific elucidation for use of the ancient Chinese formula to treat the impaired TGF-beta1 signaling-associated neuropsychiatric disorders.

Complex integration of intrinsic and peripheral signaling is required for pituitary gland development

The coordination of pituitary development is complicated and requires input from multiple cellular processes. Recent research has provided insight into key molecular determinants that govern cell fate specification in the pituitary. Moreover, increasing research aimed to identify, characterize, and functionally describe the presumptive pituitary stem cell population has allowed for a better understanding of the processes that govern endocrine cell differentiation in the developing pituitary. The culmination of this research has led to the ability of investigators to recapitulate some of embryonic pituitary development in vitro, the first steps to developing novel regenerative therapies for pituitary diseases. In this current review, we cover the major players in pituitary stem/progenitor cell function and maintenance, and the key molecular determinants of endocrine cell specification. In addition, we discuss the contribution of peripheral hormonal regulation of pituitary gland development, an understudied area of research.

Role of kisspeptin and Kiss1R in the regulation of prolactin gene expression in rat somatolactotroph GH3 cells

Hypothalamic kisspeptin is a known principal activator of gonadotropin-releasing hormone neurons and governs the hypothalamic-pituitary-gonadal axis. Previous reports have shown that kisspeptin is also released into the hypophyseal portal circulation and directly affects the anterior pituitary. In this study, we examined the direct effect of kisspeptin on pituitary prolactin-producing cells. The rat pituitary somatolactotroph cell line GH3 expresses the kisspeptin receptor (Kiss1R); however, in these cells, kisspeptin failed to stimulate prolactin-promoter activity. When GH3 cells overexpressed Kiss1R, kisspeptin clearly increased prolactin-promoter activity, with a concomitant increase in extracellular signal-regulated kinase (ERK) and cAMP/protein kinase A (PKA) signaling pathways. In the experiments using GH3 cells overexpressing Kiss1R, kisspeptin did not potentiate thyrotropin-releasing hormone (TRH)-induced prolactin-promoter activity, but it potentiated the pituitary adenylate cyclase-activating polypeptide-induced prolactin-promoter activity, with a concomitant enhancement of ERK and PKA signaling pathways. Although the basal and TRH-induced prolactin-promoter activities were not modulated by increasing amounts of Kiss1R expression in GH3 cells, kisspeptin-stimulated prolactin-promoter activity was increased by the amount of Kiss1R overexpression. Endogenous Kiss1r mRNA expression in GH3 cells was significantly increased by treatment with estradiol (E2) but not by TRH. In addition, kisspeptin's ability to stimulate prolactin-promoter activity was restored after E2 treatment in non-transfected GH3 cells. Our current observations suggest that kisspeptin might have a direct effect on prolactin expression in the anterior pituitary prolactin-producing cells under the influence of E2, which may regulate Kiss1R expression and function.

Pituitary genomic expression profiles of steers are altered by grazing of high vs. low endophyte-infected tall fescue forages

Consumption of ergot alkaloid-containing tall fescue grass impairs several metabolic, vascular, growth, and reproductive processes in cattle, collectively producing a clinical condition known as "fescue toxicosis." Despite the apparent association between pituitary function and these physiological parameters, including depressed serum prolactin; no reports describe the effect of fescue toxicosis on pituitary genomic expression profiles. To identify candidate regulatory mechanisms, we compared the global and selected targeted mRNA expression patterns of pituitaries collected from beef steers that had been randomly assigned to undergo summer-long grazing (89 to 105 d) of a high-toxic endophyte-infected tall fescue pasture (HE; 0.746 μg/g ergot alkaloids; 5.7 ha; n = 10; BW = 267 ± 14.5 kg) or a low-toxic endophyte tall fescue-mixed pasture (LE; 0.023 μg/g ergot alkaloids; 5.7 ha; n = 9; BW = 266 ± 10.9 kg). As previously reported, in the HE steers, serum prolactin and body weights decreased and a potential for hepatic gluconeogenesis from amino acid-derived carbons increased. In this manuscript, we report that the pituitaries of HE steers had 542 differentially expressed genes (P < 0.001, false discovery rate ≤ 4.8%), and the pattern of altered gene expression was dependent (P < 0.001) on treatment. Integrated Pathway Analysis revealed that canonical pathways central to prolactin production, secretion, or signaling were affected, in addition to those related to corticotropin-releasing hormone signaling, melanocyte development, and pigmentation signaling. Targeted RT-PCR analysis corroborated these findings, including decreased (P < 0.05) expression of DRD2, PRL, POU1F1, GAL, and VIP and that of POMC and PCSK1, respectively. Canonical pathway analysis identified HE-dependent alteration in signaling of additional pituitary-derived hormones, including growth hormone and GnRH. We conclude that consumption of endophyte-infected tall fescue alters the pituitary transcriptome profiles of steers in a manner consistent with their negatively affected physiological parameters.

Regulatory role of melatonin and BMP-4 in prolactin production by rat pituitary lactotrope GH3 cells

The effects of melatonin on prolactin production and its regulatory mechanism remain uncertain. We investigated the regulatory role of melatonin in prolactin production using rat pituitary lactotrope GH3 cells by focusing on the bone morphogenetic protein (BMP) system. Melatonin receptor activation, induced by melatonin and its receptor agonist ramelteon, significantly suppressed basal and forskolin-induced prolactin secretion and prolactin mRNA expression in GH3 cells. The melatonin MT2 receptor was predominantly expressed in GH3 cells, and the inhibitory effects of melatonin on prolactin production were reversed by treatment with the receptor antagonist luzindole, suggesting functional involvement of MT2 action in the suppression of prolactin release. Melatonin receptor activation also suppressed BMP-4-induced prolactin expression by inhibiting phosphorylation of Smad and transcription of the BMP-target gene Id-1, while BMP-4 treatment upregulated MT2 expression. Melatonin receptor activation suppressed basal, BMP-4-induced and forskolin-induced cAMP synthesis; however, BtcAMP-induced prolactin mRNA expression was not affected by melatonin or ramelteon, suggesting that MT2 activation leads to inhibition of prolactin production through the suppression of Smad signaling and cAMP synthesis. Experiments using intracellular signal inhibitors revealed that the ERK pathway is, at least in part, involved in prolactin induction by GH3 cells. Thus, a new regulatory role of melatonin involving BMP-4 in prolactin secretion was uncovered in lactotrope GH3 cells.

Prolactin function and putative expression in the brain

INTRODUCTION

Prolactin is a peptide hormone mainly synthetized and secreted by the anterior pituitary gland, but also by extrapituitary tissues, such as mammary gland, decidua, prostate, skin, and possibly the brain. Similarly, prolactin receptor is expressed in the pituitary gland, many peripheral tissues, and in contrast to prolactin, its receptor has been consistently detected in several brain regions, such as cerebral cortex, olfactory bulb, hypothalamus, hippocampus, amygdala, among others. Classically, prolactin function has been related to the stimulation of lactogenesis and galactopoiesis, however, it is well known that prolactin induces a wide range of functions in different brain areas.

PURPOSE

The aim of this review is to summarize recent reports on prolactin and prolactin receptor synthesis and localization, as well as recapitulate both the classic functions attributed to this hormone in the brain and the recently described functions such as neurogenesis, neurodevelopment, sleep, learning and memory, and neuroprotection.

CONCLUSION

The distribution and putative expression of prolactin and its receptors in several neuronal tissues suggests that this hormone has pleiotropic functions in the brain.

Decidualization is Impaired in Endometrial Stromal Cells from Uterine Rudiments in Mayer-Rokitansky-Küster-Hauser Syndrome

BACKGROUND/AIMS

Uterine rudiments from patients with Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) contain all tissues typically found in the uterus. Endometrium from the rudiments predominantly exhibits basalis-like features, and endometrial proliferative capacity in patients' epithelium and stroma is significantly lower.

METHODS

This single-center, prospective study conducted at a major German university hospital compared in-vitro decidualization in cultured ESCs from MRKHS patients and hysterectomy controls. Primary ESC cultures were established from both sources. Hormone-induced prolactin and IGFBP-1 secretion served as a measure of their ability to undergo decidualization in response to hormonal stimulation. Expression levels of 8 key marker genes of decidualization were also determined.

RESULTS

At day 9, mean secretion of prolactin and IGFBP-1 was significantly reduced by 89.0% and 99.5%, respectively, in MRKHS ESCs vs. hysterectomy controls, both indicating impaired decidualization of MRKHS ESCs. Key decidual markers confirmed impaired decidualization in MRKHS patients.

CONCLUSION

Our results indicate that the ESCs from MRKHS patients lack hormone responsiveness as a potential sign of dysfunctional hormone receptor function, which may also play a role in the onset of MRKHS. Further studies are needed to corroborate our findings, directly address receptor function, and elucidate the role of other potential determinants of uterine development and adult function.

Inactivation of the melanin concentrating hormone system impairs maternal behavior

In order to prepare the mother for the demands of pregnancy and lactation, the maternal brain is subjected to a number of adaptations. Maternal behaviors are regulated by complex neuronal interactions. Here, we show that the melanin concentrating hormone (MCH) system is an important regulator of maternal behaviors. First, we report that melanin concentrating hormone receptor 1 knockout (MCHR1 KO) mice display a disruption of maternal behavior. Early postpartum MCHR1 KO females exhibit poor nesting, deficits in pup retrieval and maternal aggression. In addition, ablation of MCH receptors results in decreased milk production and prolactin mRNA levels. Then we show that these results are in line with those obtained in wild type mice (WT) treated with the specific MCHR1 antagonist GW803430. Furthermore, following pups retrieval, MCHR1 KO mice display a lower level of Fos expression than WT mice in the ventral tegmental area, and nucleus accumbens. With the progression of the lactation period, however, the MCHR1 KO mice improve maternal care towards their pups. This is manifested by an increase in the pups׳ survival rate and the decrease in pups׳ retrieval time beyond the second day after parturition. In conclusion, we show that the MCH system plays a significant role in the initiation of maternal behavior. In this context, MCH may play a role in integrating information from multiple sources, and connecting brain reward, homeostatic and regulatory systems.

Genomic analyses identify agents regulating somatotroph and lactotroph functions

Isolated hormone deficiency might be caused by loss of a specific type of endocrine cells, and regenerating these missing cells may provide a new option for future treatment. It is known that POU1F1 lineage cells can differentiate into thyrotroph, somatotroph, and lactotroph. However, there is no effective way of controlling pituitary stem/progenitor cells to differentiate into a specific type of endocrine cell. We thereby analyzed multiple genomic publications related to POU1F1 and pituitary development in this study to identify genes and agents regulating POU1F1 lineage cell differentiation. ANOVA analyses were performed to obtain differentially expressed genes. Ingenuity pathway analyses were performed to obtain signaling pathways, interaction networks, and upstream regulators. Venn diagram was used to determine the overlapping information between studies. Summary statistics was performed to rank genes according to their frequency of occurrence in these studies. The results from upstream analyses indicated that 326 agents may regulate pituitary cell differentiation. These agents can be categorized into 12 groups, including hormones and related pathways, PKA-cAMP pathways, p53/DNA damaging/cell cycle pathways, immune/inflammation regulators, growth factor and downstream pathways, retinoic/RAR pathways, ROS pathways, histone modifications, CCAAT/enhancer binding protein family, neuron development/degeneration pathways, calcium related and fat acid, and glucose pathways. Additional experiments demonstrated that H₂O₂ and catalase differentially regulate growth hormone and prolactin expression in somatolactotroph cells, confirming potential roles of ROS pathway on regulating somatotroph and lactotroph functions.

A Common Phenotype Polymorphism in Mammalian Brains Defined by Concomitant Production of Prolactin and Growth Hormone

Pituitary Prolactin (PRL) and Growth Hormone (GH) are separately controlled and sub-serve different purposes. Surprisingly, we demonstrate that extra-pituitary expression in the adult mammalian central nervous system (CNS) is coordinated at mRNA and protein levels. However this was not a uniform effect within populations, such that wide inter-individual variation was superimposed on coordinate PRL/GH expression. Up to 44% of individuals in healthy cohorts of mice and rats showed protein levels above the norm and coordinated expression of PRL and GH transcripts above baseline occurred in the amygdala, frontal lobe and hippocampus of 10% of human subjects. High levels of PRL and GH present in post mortem tissue were often presaged by altered responses in fear conditioning and stress induced hyperthermia behavioral tests. Our data define a common phenotype polymorphism in healthy mammalian brains, and, given the pleiotropic effects known for circulating PRL and GH, further consequences of coordinated CNS over-expression may await discovery.

Bovine lactotroph cultures for the study of prolactin synthesis functions

The aim of this study was to establish a bovine anterior pituitary-derived lactotroph (BAPDL) line that expresses prolactin (PRL) in vitro to study the mechanisms of bovine PRL synthesis and secretion. Immunohistochemistry assay of PRL in the newborn calves' anterior pituitary glands showed that most lactotrophs were located within the superior border of the lateral wings of the anterior pituitary. Tissues of the superior border of the lateral wings of the anterior pituitary were dispersed and cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS). The limiting dilution method was used to establish BAPDL from single cell clone. BAPDL cells constantly expressed mRNAs for PRL and pituitary-specific transcription factor 1 (Pit-1) gene and grew steadily and rapidly in the DMEM supplemented with 10% FBS. PRL immunoreactivity was present in BAPDL at passage 20. The concentration of bovine PRL in BAPDL at passage 20 culture supernatant was decreased to below 35% compared with that in BAPDL at passage 1. The effects of human epidermal growth factor (hEGF) and dopamine (DA) on the expression and secretion of PRL in BAPDL at passage 4 were also investigated. The results are consistent with those of previous studies. Thus, it can be used successfully for studying the mechanisms of stimuli regulating PRL synthesis and release.

Role of thyrotropin-releasing hormone in prolactin-producing cell models

Thyrotropin-releasing hormone (TRH) is a hypothalamic hypophysiotropic neuropeptide that was named for its ability to stimulate the release of thyroid-stimulating hormone in mammals. It later became apparent that it exerts a number of species-dependent hypophysiotropic activities that regulate other pituitary hormones. TRH also regulates the synthesis and release of prolactin, although whether it is a physiological regulator of prolactin that remains unclear. Occupation of the Gq protein-coupled TRH receptor in the prolactin-producing lactotroph increases the turnover of inositol, which in turn activates the protein kinase C pathway and the release of Ca(2+) from storage sites. TRH-induced signaling events also include the activation of extracellular signal-regulated kinase (ERK) and induction of MAP kinase phosphatase, an inactivator of activated ERK. TRH stimulates prolactin synthesis through the activation of ERK, whereas prolactin release occurs via elevation of intracellular Ca(2+). We have been investigating the role of TRH in a pituitary prolactin-producing cell model. Rat pituitary somatolactotroph GH3 cells, which produce and release both prolactin and growth hormone (GH), are widely used as a model for the study of prolactin- and GH-secreting cells. In this review, we describe the general action of TRH as a hypophysiotropic factor in vertebrates and focus on the role of TRH in prolactin synthesis using GH3 cells.

Fetal Alcohol Exposure Reduces Dopamine Receptor D2 and Increases Pituitary Weight and Prolactin Production via Epigenetic Mechanisms

Recent evidence indicated that alcohol exposure during the fetal period increases the susceptibility to tumor development in mammary and prostate tissues. Whether fetal alcohol exposure increases the susceptibility to prolactin-producing tumor (prolactinoma) development in the pituitary was studied by employing the animal model of estradiol-induced prolactinomas in Fischer 344 female rats. We employed an animal model of fetal alcohol exposure that simulates binge alcohol drinking during the first two trimesters of human pregnancy and involves feeding pregnant rats with a liquid diet containing 6.7% alcohol during gestational day 7 to day 21. Control rats were pair-fed with isocaloric liquid diet or fed ad libitum with rat chow diet. Adult alcohol exposed and control female offspring rats were used in this study on the day of estrus or after estrogen treatment. Results show that fetal alcohol-exposed rats had increased levels of pituitary weight, pituitary prolactin (PRL) protein and mRNA, and plasma PRL. However, these rats show decreased pituitary levels of dopamine D2 receptor (D2R) mRNA and protein and increased pituitary levels of D2R promoter methylation. Also, they show elevated pituitary mRNA levels of DNA methylating genes (DNMT1, DNMT3b, MeCP2) and histone modifying genes (HDAC2, HDAC4, G9a). When fetal alcohol exposed rats were treated neonatally with a DNA methylation inhibitor 5-Aza deoxycytidine and/or a HDAC inhibitor trichostatin-A their pituitary D2R mRNA, pituitary weights and plasma PRL levels were normalized. These data suggest that fetal alcohol exposure programs the pituitary to increase the susceptibility to the development of prolactinomas possibly by enhancing the methylation of the D2R gene promoter and repressing the synthesis and control of D2R on PRL-producing cells.

Distinct functions of neuromedin u and neuromedin s in orange-spotted grouper

Neuromedin U (NMU) and neuromedin S (NMS) play inhibitory roles in the regulation of food intake and energy homeostasis in mammals. However, their functions are not clearly established in teleost fish. In the present study, nmu and nms homologs were identified in several fish species. Subsequently, their cDNA sequences were cloned from the orange-spotted grouper (Epinephelus coioides). Sequence analysis showed that the orange-spotted grouper Nmu proprotein contains a 21-amino acid mature Nmu peptide (Nmu-21). The Nms proprotein lost the typical mature Nms peptide, but it retains a putative 34-amino acid peptide (Nmsrp). In situ hybridization revealed that nmu- and nms-expressing cells are mainly localized in the hypothalamic regions associated with appetite regulation. Food deprivation decreased the hypothalamic nmu mRNA levels but induced an increase of nms mRNA levels. Periprandial expression analysis showed that hypothalamic expression of nmu increased significantly at 3 h post-feeding, while nms expression was elevated at the normal feeding time. I.p. injection of synthetic Nmu-21 peptide suppressed the hypothalamic neuropeptide y (npy) expression, while Nmsrp administration significantly increased the expression of npy and orexin in orange-spotted grouper. Furthermore, the mRNA levels of LH beta subunit (lhβ) and gh in the pituitary were significantly down-regulated after Nmu-21 peptide administration, while Nmsrp was able to significantly stimulate the expression of FSH beta subunit (fshβ), prolactin (prl), and somatolaction (sl). Our results indicate that nmu and nms possess distinct neuroendocrine functions and pituitary functions in the orange spotted grouper.

Grass carp prolactin: molecular cloning, tissue expression, intrapituitary autoregulation by prolactin and paracrine regulation by growth hormone and luteinizing hormone

Prolactin (PRL), a pituitary hormone with diverse functions, is well-documented to be under the control of both hypothalamic and peripheral signals. Intrapituitary modulation of PRL expression via autocrine/paracrine mechanisms has also been reported, but similar information is still lacking in lower vertebrates. To shed light on autocrine/paracrine regulation of PRL in fish model, grass carp PRL was cloned and its expression in the carp pituitary has been confirmed. In grass carp pituitary cells, local secretion of PRL could suppress PRL release with concurrent rises in PRL production and mRNA levels. Paracrine stimulation by growth hormone (GH) was found to up- regulate PRL secretion, PRL production and PRL transcript expression, whereas the opposite was true for the local actions of luteinizing hormone (LH). Apparently, local interactions of PRL, GH and LH via autocrine/paracrine mechanisms could modify PRL production in carp pituitary cells through differential regulation of PRL mRNA stability and gene transcription.

Prolactin induces up-regulation of its cognate receptor in breast cancer cells via transcriptional activation of its generic promoter by cross-talk between ERα and STAT5

Prolactin (PRL) serves a critical role in breast cancer progression via activation of its cognate receptor. These studies reveal up-regulation of PRLR gene expression by PRL in absence of estradiol in MCF-7 and T47D breast cancer cells. PRL/PRLR via activation of STAT5 that binds a GAS-element in the PRLR gene and the participation of ERα stimulates PRLR transcription/expression. PRL/PRLR induces phosphorylation of ERα through the JAK2/PI3K/MAPK/ERK and JAK2/HER2 activated pathways. The increased recruitment of phospho-ERα, induced by PRL to Sp1 and C/EBPβ at PRLR promoter sites is essential for PRL-induced PRLR transcription. This recruitment is prevented by blockade of PRL expression using RNA interference or ERα phosphorylation using specific inhibitors of PI3K and ERK. Direct evidence is provided for local actions of PRL, independent of estradiol, in the up-regulation of PRLR transcription/expression by an activation-loop between STAT5 and the phospho-ERα/Sp1/C/EBPβ complex with requisite participation of signaling mechanisms. PRL's central role in the up-regulation of PRLR maximizes the action of the endogenous hormone. This study offers mechanistically rational basis for invasiveness fueled by prolactin in refractory states to adjuvant therapies in breast cancer.

Vasoinhibins, N-terminal mouse prolactin fragments, participate in mammary gland involution

Vasoinhibins are a family of peptides that act on endothelial cells to suppress angiogenesis and promote apoptosis-mediated vascular regression. Vasoinhibins include the N-terminal fragments from prolactin (PRL), GH, and placental lactogen. One of the vasoinhibins, the N-terminal PRL fragment of 16 kDa, is generated by the lysosomal representative protease cathepsin D (Cath D). Because the normal growth and involution of the mammary gland (MG) are profoundly affected by the expansion and regression of blood vessels and also because PRL stimulates the growth and differentiation of MG, we proposed that intact PRL produced during lactation contributes to MG angiogenesis and increased blood flow, whereas during involution, the N-terminal PRL fragment would have proapoptotic effects on mammary epithelial cells (MECs). Therefore, we investigated the production of the N-terminal PRL fragment and its direct effect on the MG. Mouse PRL (mPRL) was proteolytically cleaved by Cath D between amino acids 148 and 149. N-terminal PRL fragment and Cath D expression increased during MG involution. Furthermore, incubation of MG fragments and MCF7 with recombinant 16 kDa mPRL revealed a proapoptotic effect in MECs. Ectopic mPRL in MECs was cleaved to 16 kDa PRL by Cath D in the MG lysosomal fraction. The majority of PRL derived from pituitary gland was cleaved to 16 kDa PRL in culture medium. Therefore, N-terminal PRL fragment increases during the involution period, has a proapoptotic effect on MECs, and is mainly generated by secreted Cath D in the extracellular space of MG.

Reproductive actions of prolactin mediated through short and long receptor isoforms

Prolactin (PRL) is a polypeptide hormone with a wide range of physiological functions, and is critical for female reproduction. PRL exerts its action by binding to membrane bound receptor isoforms broadly classified as the long form and the short form receptors. Both receptor isoforms are highly expressed in the ovary as well as in the uterus. Although signaling through the long form is believed to be more predominant, it remains unclear whether activation of this isoform alone is sufficient to support reproductive functions or whether both types of receptor are required. The generation of transgenic mice selectively expressing either the short or the long form of PRL receptor has provided insight into the differential signaling mechanisms and physiological functions of these receptors. This review describes the essential finding that both long and short receptor isoforms are crucial for ovarian functions and female fertility, and highlights novel mechanisms of action for these receptors.

Prolonged stimulation with thyrotropin-releasing hormone and pituitary adenylate cyclase-activating polypeptide desensitize their receptor functions in prolactin-producing GH3 cells

We used somatolactotroph GH3 cells to examine changes in response to stimulation with thyrotropin-releasing hormone (TRH) and pituitary adenylate cyclase-activating polypeptide (PACAP) after sustained treatment with these peptides. TRH and PACAP increased prolactin promoter activity in mock- and PACAP type 1 receptor (PAC1R)-transfected cells. When the cells were pretreated with TRH for 48 h, the response of the prolactin promoter to both TRH and PACAP was diminished. Similarly, in PAC1R-transfected GH3 cells pretreated with PACAP, the effects of TRH and PACAP on the prolactin promoter were eliminated. The stimulation of prolactin mRNA expression by TRH and PACAP was eliminated by prolonged pretreatment with these peptides in PAC1R-transfected cells. Both the serum response element (SRE) promoters and cAMP response element (CRE) promoters were activated by TRH and PACAP in either mock- or PAC1R-transfected cells. Pretreatment for 48 h with TRH also eliminated the effects of TRH and PACAP on the SRE and CRE promoters, and pretreatment of PAC1R-transfected cells with PACAP for 48 h reduced the responses of the SRE and CRE promoters to TRH and PACAP. These observations demonstrated that sustained stimulation with TRH and PACAP desensitizes their own and each other's receptors.

Neuropeptide TLQP-21, a VGF internal fragment, modulates hormonal gene expression and secretion in GH3 cell line

In the present study we demonstrated that TLQP-21, a biologically active peptide derived from the processing of the larger pro-VGF granin, plays a role in mammotrophic cell differentiation. We used an established in vitro model, the GH3 cell line, which upon treatment with epidermal growth factor develops a mammotrophic phenotype consisting of induction of prolactin expression and secretion, and inhibition of growth hormone. Here we determined for the first time that during mammotrophic differentiation, epidermal growth factor also induces Vgf gene expression and increases VGF protein precursor processing and peptide secretion. After this initial observation we set out to determine the specific role of the VGF encoded TLQP-21 peptide on this model. TLQP-21 induced a trophic effect on GH3 cells and increased prolactin expression and its own gene transcription without affecting growth hormone expression. TLQP-21 was also able to induce a significant rise of cytoplasmic calcium, as measured by Fura2AM, due to the release from a thapsigargin-sensitive store. TLQP-21-dependent rise in cytoplasmic calcium was, at least in part, dependent on the activation of phospholipase followed by phosphorylation of PKC and ERK. Taken together, the present results demonstrate that TLQP-21 contributes to differentiation of the GH3 cell line toward a mammotrophic phenotype and suggest that it may exert a neuroendocrine role in vivo on lactotroph cells in the pituitary gland.

Cadmium as an endocrine disruptor: correlation with anterior pituitary redox and circadian clock mechanisms and prevention by melatonin

To examine the effect of a low dose of cadmium (Cd) as an endocrine disruptor, male Wistar rats received CdCl2 (5ppm Cd) in drinking water or drinking water alone. After 1 month, the rats were euthanized at one of six time intervals around the clock and the 24-h pattern of adenohypophysial prolactin (PRL) synthesis and release, lipid peroxidation, and redox enzyme and metallothionein (MT) gene expression was examined. Cd suppressed 24-h rhythmicity in expression of the PRL gene and in circulating PRL by increasing them at early photophase only, in correlation with an augmented pituitary lipid peroxidation and redox enzyme expression. CdCl2 treatment effectively disrupted the 24-h variation in expression of every pituitary parameter tested except for MT-3. In a second experiment the effect of melatonin (3μg/ml in drinking water) was assessed at early photophase, the time of maximal endocrine-disrupting effect of Cd. Melatonin treatment blunted the effect of Cd on PRL synthesis and release, decreased Cd-induced lipid peroxidation, and counteracted the effect of Cd on expression of most redox enzymes. A third experiment was performed to examine whether melatonin could counteract Cd-induced changes in the 24-h pattern of pituitary circadian clock gene expression and plasma PRL, luteinizing hormone (LH), thyrotropin (TSH), and corticosterone levels. Rats receiving CdCl2 exhibited a suppressed daily rhythm of Clock expression and a significant disruption in daily rhythms of pituitary Bmal1, Per1, Per2, Cry1, and Cry2. The coadministration of melatonin restored rhythmicity in Clock and Bmal1 expression but shifted the maxima in pituitary Per1, Cry1, and Cry2 expression to the scotophase. Melatonin also counteracted the effect of Cd on 24-h rhythmicity of circulating PRL, LH, TSH, and corticosterone. The results highlight the occurrence of a significant endocrine disruptor effect of a low dose of Cd. Generally melatonin counteracted the effects of Cd and ameliorated partially the circadian disruption caused by the pollutant.

[Noradrenaline role in regulation of dopamine-producing neurons in rat arcuate nucleus]

Among most important functions of the neuroendocrine system is the regulation of reproduction, including the inhibitory control of prolactin secretion by dopamine (DA) synthesized in the arcuate nucleus (AN). Besides DA, noradrenaline (NA) contributes to this regulation though, in contrast DA, its concrete functional role remains to be uncertain. In the previous studies, it has been suggested that NA inhibits compensatory synthesis of DA in DA-producing neurons of AN under the failure of the dopaminergic system though no evidence were obtained. Therefore, the goal of this study was to specify the role of NA in the regulation of DA-producing neurons in AN. Two pharmacological models were used to this aim: a) switching off dopaminergic and noradrenergic neurons and their afferents in An or b) switching of only dopaminergic neurons and afferents that allowed us to recognize NA role in the complex catecholaminergic regulation of prolactin secretion. According to our data, the maintaining of the noradrenergic innervation of AN under the neurotoxin-induced failure of dopaminergic neurons resulted in the decrease of the expression of tyrosine hydroxylase (TH), the first enzyme ofDA synthesis, thereby enhancing DA deficit. This is considered as direct evidence of noradrenergic inhibitory control of TH expression in the neurons of AN.

A transcriptome-wide screen for mRNAs enriched in fetal Leydig cells: CRHR1 agonism stimulates rat and mouse fetal testis steroidogenesis

Fetal testis steroidogenesis plays an important role in the reproductive development of the male fetus. While regulators of certain aspects of steroidogenesis are known, the initial driver of steroidogenesis in the human and rodent fetal testis is unclear. Through comparative analysis of rodent fetal testis microarray datasets, 54 candidate fetal Leydig cell-specific genes were identified. Fetal mouse testis interstitial expression of a subset of these genes with unknown expression (Crhr1, Gramd1b, Itih5, Vgll3, and Vsnl1) was verified by whole-mount in situ hybridization. Among the candidate fetal Leydig cell-specific factors, three receptors (CRHR1, PRLR, and PROKR2) were tested for a steroidogenic function using ex vivo fetal testes treated with receptor agonists (CRH, PRL, and PROK2). While PRL and PROK2 had no effect, CRH, at low (approximately 1 to 10) nM concentration, increased expression of the steroidogenic genes Cyp11a1, Cyp17a1, Scarb1, and Star in GD15 mouse and GD17 rat testes, and in conjunction, testosterone production was increased. Exposure of GD15 fetal mouse testis to a specific CRHR1 antagonist blunted the CRH-induced steroidogenic gene expression and testosterone responses. Similar to ex vivo rodent fetal testes, ≥10 nM CRH exposure of MA-10 Leydig cells increased steroidogenic pathway mRNA and progesterone levels, showing CRH can enhance steroidogenesis by directly targeting Leydig cells. Crh mRNA expression was observed in rodent fetal hypothalamus, and CRH peptide was detected in rodent amniotic fluid. Together, these data provide a resource for discovering factors controlling fetal Leydig cell biology and suggest that CRHR1 activation by CRH stimulates rat and mouse fetal Leydig cell steroidogenesis in vivo.

Roles of dopamine 2 receptor isoforms and g proteins in ethanol regulated prolactin synthesis and lactotropic cell proliferation

Alcohol consumption has been shown to increase prolactin (PRL) production and cell proliferation of pituitary lactotropes. It also causes a reduction in the lactotrope's response to dopaminergic agents and a differential expression of dopamine 2 receptor short (D2S) and long (D2L) isoforms in the pituitary. However, the role of each of these D2 receptor isoforms and its coupled G protein in mediation of ethanol actions on lactotropes is not known. We have addressed this issue by comparing ethanol effects on the level of PRL production gene transcription rate cellular protein, G proteins and cell proliferation in enriched lactotropes and lactotrope-derived PR1 cells containing various D2 receptor isoforms. Additionally, we determined the effects of G protein blockade on ethanol-induced PRL production and cell proliferation in these cells. We show here that the D2 receptor, primarily the D2S isoform, is critically involved in the regulation of ethanol actions on PRL production and cell proliferation in lactotropes. We also present data to elucidate that the presence of the pertussis toxin (PTX)-sensitive D2S receptor is critical to mediate the ethanol stimulatory action on Gs and the ethanol's inhibitory action on Gi3 protein in lactotropes. Additionally, we provide evidence for the existence of an inhibitory action of Gi3 on Gs that is under the control of the D2S receptor and is inhibited by ethanol. These results suggest that ethanol via the inhibitory action on D2S receptor activity suppresses Gi3 repression of Gs expression resulting in stimulation of PRL synthesis and cell proliferation in lactotropes.

The forkhead transcription factor, FOXP3, is required for normal pituitary gonadotropin expression in mice

The hypothalamic-pituitary-gonadal axis is central to normal reproductive function. This pathway begins with the release of gonadotropin-releasing hormone in systematic pulses by the hypothalamus. Gonadotropin-releasing hormone is bound by receptors on gonadotroph cells in the anterior pituitary gland and stimulates the synthesis and secretion of luteinizing hormone and, to some extent, follicle-stimulating hormone. Once stimulated by these glycoprotein hormones, the gonads begin gametogenesis and the synthesis of sex hormones. In humans, mutations of the forkhead transcription factor, FOXP3, lead to an autoimmune disorder known as immunodysregulation, polyendocrinopathy, and enteropathy, X-linked syndrome. Mice with a mutation in the Foxp3 gene have a similar autoimmune syndrome and are infertile. To understand why FOXP3 is required for reproductive function, we are investigating the reproductive phenotype of Foxp3 mutant mice (Foxp3(sf/Y)). Although the gonadotroph cells appear to be intact in Foxp3(sf/Y) mice, luteinizing hormone beta (Lhb) and follicle-stimulating hormone beta (Fshb) expression are significantly decreased, demonstrating that these mice exhibit a hypogonadotropic hypogonadism. Hypothalamic expression of gonadotropin-releasing hormone is not significantly decreased in Foxp3(sf/Y) males. Treatment of Foxp3(sf/Y) males with a gonadotropin-releasing hormone receptor agonist does not rescue expression of Lhb or Fshb. Interestingly, we do not detect Foxp3 expression in the pituitary or hypothalamus, suggesting that the infertility seen in Foxp3(sf/Y) males is a secondary effect, possibly due to loss of FOXP3 in immune cells. Pituitary expression of glycoprotein hormone alpha (Cga) and prolactin (Prl) are significantly reduced in Foxp3(sf/Y) males, whereas the precursor for adrenocorticotropic hormone, pro-opiomelanocortin (Pomc), is increased. Human patients diagnosed with IPEX often exhibit thyroiditis due to destruction of the thyroid gland by autoimmune cells. We find that Foxp3(sf/Y) mice have elevated expression of thyroid-stimulating hormone beta (Tshb), suggesting that they may suffer from thyroiditis as well. Expression of the pituitary transcription factors, Pitx1, Pitx2, Lhx3, and Egr1, is normal; however, expression of Foxl2 and Gata2 is elevated. These data are the first to demonstrate a defect at the pituitary level in the absence of FOXP3, which contributes to the infertility observed in mice with Foxp3 loss of function mutations.

Prolactin177, prolactin188 and prolactin receptor 2 in the pituitary of the euryhaline tilapia, Oreochromis mossambicus, are differentially osmosensitive

Two forms of prolactin (Prl), prolactin 177 (Prl(177)) and prolactin 188 (Prl(188)), are produced in the rostral pars distalis (RPD) of the pituitary gland of euryhaline Mozambique tilapia, Oreochromis mossambicus. Consistent with their roles in fresh water (FW) osmoregulation, release of both Prls is rapidly stimulated by hyposmotic stimuli, both in vivo and in vitro. We examined the concurrent dynamics of Prl(177) and Prl(188) hormone release and mRNA expression from Prl cells in response to changes in environmental salinity in vivo and to changes in extracellular osmolality in vitro. In addition, mRNA levels of Prl receptors 1 and 2 (prlr1 and prlr2) and osmotic stress transcription factor 1 (ostf1) were measured. Following transfer from seawater (SW) to FW, plasma osmolality decreased, while plasma levels of Prl(177) and Prl(188) and RPD mRNA levels of prl(177) and prl(188) increased. The opposite pattern was observed when fish were transferred from FW to SW. Moreover, hyposmotically induced release of Prl(188) was greater in Prl cells isolated from FW-acclimated fish after 6 h of incubation, while the hyposmotically induced increase in prl(188) mRNA levels was only observed in SW-acclimated fish. In addition, prlr2 and ostf1 mRNA levels in Prl cells from both FW- and SW-acclimated fish increased in direct proportion to increases in extracellular osmolality both in vivo and in vitro. Taken together, these results indicate that the osmosensitivity of the tilapia RPD is modulated by environmental salinity with respect to hormone release and gene expression.

Effects of estradiol and progesterone on prolactin transcriptional activity in somatolactotrophic cells

We examined the effects of sex steroids on prolactin promoter activity in rat somatolactotrophic GH3 cells. Both estradiol (E2) and progesterone (P4) were found to inhibit basal prolactin promoter activity, but to potentiate Thyrotropin-releasing hormone (TRH)-induced prolactin promoter activity. P4 had a greater inhibitory effect on basal prolactin promoter activity than E2, and P4 also potentiated TRH-induced prolactin promoter more potently than E2. Combined treatment with E2 and P4 further increased TRH-induced prolactin promoter activity. E2 and P4 also both reduced basal serum response element (SRE) promoter activity, and increased TRH-induced SRE promoter activity. Combination treatment with E2 and P4 reduced basal activity of SRE promoter and increased TRH-induced SRE activity more potently than E2 or P4 alone. In contrast, basal cAMP response element (CRE) promoter activity was not influenced by either E2 or P4, although TRH-induced CRE promoter was potentiated by each of these steroids, and was further increased by E2 and P4 combination treatment. Both E2 and P4 increased TRH-induced extracellular signal-regulated kinase (ERK) phosphorylation; however, intracellular cAMP levels was not influenced by E2 or P4. TRH-induced CRE promoter was inhibited by mitogen-activated protein kinase/ERK kinase (MEK) inhibitor and was increased by overexpression of MEK kinase (MEKK). This study showed that ERK and SRE transcriptional pathways, but not the cAMP/CRE pathway, may be involved in the suppression of basal prolactin promoter activity, whereas both the ERK/SRE and MAP kinase-mediated CRE pathways appear to be involved in the increased transcriptional efficiency of the prolactin promoter induced by TRH stimulation.

Tumor expression of human growth hormone and human prolactin predict a worse survival outcome in patients with mammary or endometrial carcinoma

CONTEXT

Evidence suggests that human GH (hGH) and human prolactin (hPRL) possess an autocrine or paracrine oncogenic role in mammary and endometrial carcinoma. However, especially for hGH, the prognostic relevance of tumor expression of these hormones is not well defined.

OBJECTIVE

We investigated the potential association of tumor mRNA and protein expression of hGH and hPRL with the clinicopathological features of mammary and endometrial carcinoma. The prognostic relevance of the individual or combined expression of hGH and hPRL in mammary and endometrial carcinoma was also determined.

DESIGN

The expression of hGH and hPRL was analyzed in histopathological samples of mammary and endometrial carcinoma, and the respective normal tissues, by in situ hybridization and immunohistochemistry. Kaplan-Meier and Cox regression analysis was performed to examine the association of tumor hGH and hPRL expression with relapse-free survival and overall survival of patients.

RESULTS

hGH expression was significantly associated with lymph node metastasis, tumor stage, human epidermal growth factor receptor-2 status, and proliferative index in mammary carcinoma and with International Federation of Gynecology and Obstetrics grade, myometrial invasion, and ovarian metastases in endometrial carcinoma. hPRL expression was associated with lymph node metastasis, tumor grade, and tumor stage in mammary carcinoma and with International Federation of Gynecology and Obstetrics stage and myometrial invasion in endometrial carcinoma. Both hGH and hPRL expression, individually and combined, are associated with worse relapse-free survival and overall survival in patients with mammary or endometrial carcinoma.

CONCLUSION

Tumor expression of both hGH or hPRL in mammary or endometrial carcinoma is associated with a large and significant difference in survival outcome for patients with these tumors.

Parathyroid hormone-like hormone (PTHLH) represses decidualization of human uterine fibroblast cells by an autocrine/paracrine mechanism

CONTEXT

Parathyroid hormone-like hormone (PTHLH) is abundantly expressed by human endometrial stromal cells during decidualization. However, the role for PTHLH in the decidualization process is unknown.

OBJECTIVE

To examine the effects of PTHLH on the induction and maintenance of decidualization of human uterine fibroblast (HUF) cells in vitro.

DESIGN

HUF cells were treated with a PTHLH siRNA or a PTHLH receptor antagonist (bPTH(7-34)) before or after decidualization with medroxyprogesterone acetate (MPA), estradiol (E(2)), and prostaglandin E(2) (PGE(2)). Decidualization was monitored by immunocytochemistry and the induction of decidualization-specific marker genes, including IGFBP-1, prolactin, lefty, and transcription factor FOXO1.

RESULTS

HUF cells decidualized after pretreatment with a PTHLH siRNA showed greater morphologic changes of decidualization, greater IGFBP-1 protein, and two- to threefold more IGFBP-1, prolactin, lefty, and FOXO1 mRNAs than cells pretreated with a nonsilencing RNA. The PTHLH siRNA pretreated cells also had 31% less DNA fragmentation (TUNEL assay) and 30-35% less caspase 3 levels during decidualization than cells pretreated treated with nonsilencing RNA. Treatment of HUF cells with PTHLH siRNA or bPTH(7-34) at 9 d after the induction of decidualization also resulted in 2.1- to 3.2-fold greater IGFBP-1, prolactin, lefty, and FOXO1 mRNA levels than that noted in control cells treated with nonsilencing RNA.

CONCLUSIONS

These finding strongly suggest that PTHLH represses the induction of human decidualization, stimulates stromal cell apoptosis, and limits the extent of uterine stromal cell differentiation. Because PTHLH and its receptor are expressed by HUF cells and placental cells, the inhibitory effect of PTHLH on decidualization appears to be due, at least in part, to an autocrine/paracrine mechanism.

Update on peripartum cardiomyopathy

Although multiple mechanisms have been postulated, peripartum cardiomyopathy (PPCM) continues to be a cardiomyopathy of unknown cause. Multiple risk factors exist and the clinical presentation does not allow differentiation among potential causes. Although specific diagnostic criteria exist, PPCM remains a diagnosis of exclusion. Treatment modalities are dictated by the clinical state of the patient, and prognosis is dependent on recovery of function. Randomized controlled trials of novel therapies, such as bromocriptine, are needed to establish better treatment regimens to decrease morbidity and mortality. The creation of an international registry will be an important step to better define and treat PPCM. This article discusses the pathogenesis, risk factors, diagnosis, management, and prognosis of this condition.

MicroRNAs regulate pituitary development, and microRNA 26b specifically targets lymphoid enhancer factor 1 (Lef-1), which modulates pituitary transcription factor 1 (Pit-1) expression

To understand the role of microRNAs (miRNAs) in pituitary development, a group of pituitary-specific miRNAs were identified, and Dicer1 was then conditionally knocked out using the Pitx2-Cre mouse, resulting in the loss of mature miRNAs in the anterior pituitary. The Pitx2-Cre/Dicer1 mutant mice demonstrate growth retardation, and the pituitaries are hypoplastic with an abnormal branching of the anterior lobe, revealing a role for microRNAs in pituitary development. Growth hormone, prolactin, and thyroid-stimulating hormone β-subunit expression were decreased in the Dicer1 mutant mouse, whereas proopiomelanocortin and luteinizing hormone β-subunit expression were normal in the mutant pituitary. Further analyses revealed decreased Pit-1 and increased Lef-1 expression in the mutant mouse pituitary, consistent with the repression of the Pit-1 promoter by Lef-1. Lef-1 directly targets and represses the Pit-1 promoter. miRNA-26b (miR-26b) was identified as targeting Lef-1 expression, and miR-26b represses Lef-1 in pituitary and non-pituitary cell lines. Furthermore, miR-26b up-regulates Pit-1 and growth hormone expression by attenuating Lef-1 expression in GH3 cells. This study demonstrates that microRNAs are critical for anterior pituitary development and that miR-26b regulates Pit-1 expression by inhibiting Lef-1 expression and may promote Pit-1 lineage differentiation during pituitary development.

Endocrine gland derived-VEGF is down-regulated in human pituitary adenoma

BACKGROUND

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is an angiogenic molecule restricted to endocrine glands and, particularly, to steroid-secreting cells. The expression of EG-VEGF and its significance in human adenohypophysis in physiological and pathological conditions is still unknown.

MATERIALS AND METHODS

In this study, we investigated by immunohistochemistry the expression of EG-VEGF in 2 samples of normal adenohypophysis and 43 bioptic samples of pituitary adenoma. Moreover, the expression of growth hormone (GH), prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH) and adrenocorticoprophic hormone (ACTH) were also estimated.

RESULTS

The results of this study for the first time demonstrate a down-regulation of EG-VEGF expression in human pituitary adenoma as compared to normal adenohypophysis, suggesting an impaired function of the neoplastic cells in terms of hormone release in the blood stream, as a consequence of impaired tumor angiogenesis in the tumor.

CONCLUSION

On the basis of our data showing a marked decrease in the expression of EG-VEGF in pituitary adenoma, with the exception of LH-secreting adenomas, we suggest that LH might be involved in the induction of EG-VEGF secretion.

Changes in prolactin mRNA levels during downstream migration of the amphidromous teleost, ayu Plecoglossus altivelis

Changes in mRNA levels of prolactin (PRL) during seaward migration and after experimental transfer from fresh water (FW) to seawater (SW) were examined in larvae of the amphidromous fish, ayu Plecoglossus altivelis. In the field study, ayu larvae caught in the surf zone showed lower levels of PRL mRNA than those in the river, while growth hormone (GH) levels showed no significant change. Decrease in PRL gene transcription was also observed 24h after direct transfer from FW to SW, whereas there was no significant influence of water temperature. On the other hand, there was no significant change in GH mRNA levels in relation to SW transfer or environmental temperature. In a raceway with a vertical salinity gradient, PRL mRNA levels of ayu larvae showed a significant reduction during spontaneous migration from FW to SW, which mimicked the results from the field observation and the transfer experiment, and then a gradual increase during the course of development. Whole body water and sodium contents of larvae in a salinity gradient were stable during migration to SW. Results in this study indicated the importance of regulation of PRL gene expression in the downstream migration and acclimation to SW during the early development of ayu.

The Pit-1/Pou1f1 transcription factor regulates and correlates with prolactin expression in human breast cell lines and tumors

The transcription factor Pit-1/Pou1f1 regulates GH and prolactin (PRL) secretion in the pituitary gland. Pit-1 expression and GH regulation by Pit-1 have also been demonstrated in mammary gland. However, no data are available on the role of Pit-1 on breast PRL. To evaluate this role, several human breast cancer cell lines were transfected with either the Pit-1 expression vector or a Pit-1 small interference RNA construct, followed by PRL mRNA and protein evaluation. In addition, transient transfection of MCF-7 cells by a reporter construct containing the proximal PRL promoter, and ChIP assays were performed. Our data indicate that Pit-1 regulates mammary PRL at transcriptional level by binding to the proximal PRL promoter. We also found that Pit-1 raises cyclin D1 expression before increasing PRL levels, suggesting a PRL-independent effect of Pit-1 on cell proliferation. By using immunohistochemistry, we found a significant correlation between Pit-1 and PRL expression in 94 human breast invasive ductal carcinomas. Considering the possible role of PRL in breast cancer disorders, the function of Pit-1 in breast should be the focus of further research.

cDNA cloning of blue gourami (Trichogaster trichopterus) prolactin and its expression during the gonadal cycles of males and females

BACKGROUND

The blue gourami fish (Trichogaster trichopterus) provides a unique model for the study of reproduction endocrinology in teleost fish. Its oocyte development may be controlled easily, and the vitellogenic and final maturation phases may be separated artificially in the laboratory. Moreover, this gourami exhibits exclusive parental behavior.

AIM

The aim of the present study was to clone and sequence the blue gourami PRL (bgPRL) cDNA in order to enable the determination of its mRNA levels in the male and female blue gourami during the gonadal cycles.

MATERIALS AND METHODS

bgPRL was cloned by extracting total RNA from freshly excised pituitaries of gourami fish, followed by cDNA synthesis, rapid amplification of cDNA ends (RACE)-PCR and finally, sequencing. bgPRL mRNA expression was determined by realtime PCR, and results were normalized with 18S RNA.

RESULTS

When bgPRL was compared to PRLs of other fish, it had the most homology with PRL of Perciformes and the least with those of Anguilliformes. bgPRL was expressed during the entire gonadal cycle in males and females. The average levels of PRL mRNA in juvenile and low vitellogenetic females were lower than in mature females (at high vitellogenesis and maturation), but the differences were not significant. On the other hand, the PRL mRNA levels in mature reproductive males (nestbuilders) and non-reproductive (non-nest-builders) were significantly higher in comparison to young males.

CONCLUSIONS

The results of this study imply that PRL has a possible role in the endocrine control of gonadal development in fish, in addition to its role in reproductive behavior.

Acute and chronic stress and the inflammatory response in hyperprolactinemic rats

BACKGROUND/AIM

Prolactin (PRL), a hormone produced by the pituitary gland, has multiple physiological functions, including immunoregulation. PRL can also be secreted in response to stressful stimuli. During stress, PRL has been suggested to oppose the immunosuppressive effects of inflammatory mediators. Therefore, the aim of the present study was to analyze the effects of short- and long-term hyperprolactinemia on the inflammatory response in rats subjected to acute or chronic cold stress.

METHODS

Inflammatory edema was induced by carrageenan in male rats, and hyperprolactinemia was induced by injections of the dopamine receptor antagonist domperidone. The volume of inflammatory edema was measured by plethysmography after carrageenan injection. Additionally, the effects of hyperprolactinemia on body weight and serum corticosterone levels were evaluated.

RESULTS AND CONCLUSION

Five days of domperidone-induced hyperprolactinemia increased the volume of inflammatory edema. No differences in serum corticosterone levels were observed between groups. No significant differences were found among 30 days domperidone-induced hyperprolactinemic animals subjected to acute stress and the inflammatory response observed in chronic hyperprolactinemic animals subjected to chronic stress. The results suggest that short-term hyperprolactinemia has pro-inflammatory effects. Because such an effect was not observed in long-term hyperprolactinemic animals, PRL-induced tolerance seems likely. We suggest that short-term hyperprolactinemia may act as a protective factor in rats subjected to acute stress. These data suggest that hyperprolactinemia and stress interact differentially according to the time period.

HoxA-11 and FOXO1A cooperate to regulate decidual prolactin expression: towards inferring the core transcriptional regulators of decidual genes

During the menstrual cycle, the ovarian steroid hormones estrogen and progesterone control a dramatic transcriptional reprogramming of endometrial stromal cells (ESCs) leading to a receptive state for blastocyst implantation and the establishment of pregnancy. A key marker gene of this decidualization process is the prolactin gene. Several transcriptional regulators have been identified that are essential for decidualization of ESCs, including the Hox genes HoxA-10 and HoxA-11, and the forkhead box gene FOXO1A. While previous studies have identified downstream target genes for HoxA-10 and FOXO1A, the role of HoxA-11 in decidualization has not been investigated. Here, we show that HoxA-11 is required for prolactin expression in decidualized ESC. While HoxA-11 alone is a repressor on the decidual prolactin promoter, it turns into an activator when combined with FOXO1A. Conversely, HoxA-10, which has been previously shown to associate with FOXO1A to upregulate decidual IGFBP-1 expression, is unable to upregulate PRL expression when co-expressed with FOXO1A. By co-immunoprecipitation and chromatin immunoprecipitation, we demonstrate physical association of HoxA-11 and FOXO1A, and binding of both factors to an enhancer region (−395 to −148 relative to the PRL transcriptional start site) of the decidual prolactin promoter. Because FOXO1A is induced upon decidualization, it serves to assemble a decidual-specific transcriptional complex including HoxA-11. These data highlight cooperativity between numerous transcription factors to upregulate PRL in differentiating ESC, and suggest that this core set of transcription factors physically and functionally interact to drive the expression of a gene battery upregulated in differentiated ESC. In addition, the functional non-equivalence of HoxA-11 and HoxA-10 with respect to PRL regulation suggests that these transcription factors regulate distinct sets of target genes during decidualization.

Indirect effects of progesterone on the synthesis and secretion of prolactin in mammotroph-enriched cells

To elucidate the role of steroid hormones in the synthesis and secretion of prolactin (PRL), a mammotroph-enriched cell preparation was made by centrifugal elutriation of trypsin-dispersed anterior pituitary cells from adult male rats. The mammotrophs were enriched by about 2-fold in comparison with those in the initial cell suspension. On the other hand, the ratio of enrichment of gonadotrophs, thyrotrophs and somatotrophs was less than onetenth. The separated mammotrophs were incubated in media containing 17 beta-estradiol and/or progesterone. 17 beta-estradiol increased the levels of PRL in the medium and the cells of 300% and 140%, respectively, and the content of messenger RNA (mRNA) to 193%, whereas progesterone had no such effects. Furthermore, progesterone had no influence on the 17 beta-estradiol-induced increase in the levels of PRL and the contents of PRL mRNA. These results suggest that 17 beta-estradiol regulates PRL synthesis and secretion in mammotrophs, whereas progesterone does not.

Biological Characteristics of Cultured Cells Derived from Various Types of Human Brain Tumors

We placed in culture brain tumors from 45 cases (7 cases of astrocytoma, 2 from oligodendrogliomas, 2 glioblastomas, 2 ependymomas, 13 meningiomas, 6 pituitary adenomas, 5 neurinomas, a malignant lymphoma, a choroid plexus papilloma, and 6 metastatic tumors) and succeeded in making a primary culture from 33, and maintained 17 in vitro over a considerable period of time (greater than three months). In the early period of the primary cultures, the astrocytoma cells had cytoplasmic processes which contacted each other, the oligodendroglioma cells were small and spindle-shaped, the glioblastoma cells were neoplastic with pleopmorphic features and possessed cytoplasmic processes, the ependymoma cells formed a rosette-like cell arrangement, the meningioma cells were spindle- or round-shaped cells and characterized as forming psammoma bodies, the pituitary adenoma cells were round- or oval-shaped cells and produced growth hormone (GH), adenocorticoid tropic hormone (ACTH), prolactin, or other hypophyseal hormones, the choroid plexus papilloma cells were round-or polygonal and showed a papillary cell arrangement, the neurinoma cells were spindle- or fibrous-shaped cells, and the malignant lymphoma cells were round and formed cell aggregates floating in the culture medium.

[Regulation on the expression of bovine prolactin gene by different promoters]

To compare the regulation effects by different promoters on bovine prolactin gene expression in different cell lines, three recombinant bovine prolactin expression vectors were constructed using different promoters, i.e., CMV promoter, bovine prolactin gene promoter and goat beta-casein gene promoter, respectively named pCMV, pPRLP and pP1A3, which were transfected into two cell lines, mouse pituitary tumor cell strain (AtT20) and mouse mammary epithelial cell strain (HC11), respectively. RT-PCR and real-time RT-PCR were used to investigate the expression level of the above three vectors in both cell lines, pCMV vector was effectively expressed in both cell lines, pPRLP vector had a similar expression level to that of pCMV in both cell lines, pP1A3 was expressed in HC11 but not in AtT20. pP1A3 was tissue-specific to mammary gland, pPRLP was able to express with a significant level in pituitary and mammary glands, while its tissue-specific characteristics in other tissues need further investigation.

Pathology of the human pituitary adenomas

This article describes pertinent aspects of histochemical and molecular changes of the human pituitary adenomas. The article outlines individual tumor groups with general, specific and molecular findings. The discussion further extends to the unusual adenomas or carcinomas. The description in this article are pertinent not only for the practicing pathologists who are in the position of making proper diagnosis, but also for the pituitary research scientists who engage in solving basic problems in pituitary neoplasms by histochemistry and molecular biology.

Prolactin-releasing peptide, a possible modulator of prolactin in the euryhaline silver sea bream (Sparus sarba): A molecular study

PRL and PrRP cDNAs have been isolated from euryhaline silver sea bream (Sparus sarba). The PRL cDNA consists of 1360bp encoding 212 amino acids whereas the PrRP cDNA contains 631bp encoding preproPrRP with 122 amino acids. The mature PrRP sequence within the preprohormone is identical to the PrRPs isolated from other fish species. PRL mRNA was uniquely expressed in sea bream pituitary but PrRP mRNA was expressed in a variety of organs and tissues including the intestines, olfactory rosette and various brain regions such as hypothalamus and pituitary. Expression levels of PRL and PrRP mRNA have been examined in sea bream adapted to different salinities (0, 6, 12, 33 and 50ppt). In the pituitary, both PRL and PrRP mRNA were significantly higher in fish adapted to low salinities (0 and 6ppt) and the expression profiles of both hormones closely paralleled each other. However, expression of hypothalamic PrRP was significantly higher in fish adapted to iso-osmotic salinity (12ppt) when pituitary PRL expression was low. The present study demonstrates, for the first time, a synchronized mRNA expression pattern between PRL and PrRP in fish pituitary but a disparity of mRNA expression levels between hypothalamic PrRP and pituitary PRL during salinity adaptation. These data suggest that PrRP may possibly act as a local modulator in pituitary rather than a hypothalamic factor for regulation of pituitary PRL expression in silver sea bream.