Prolactin Production Research Articles

Early weaning by maternal prolactin inhibition leads to higher neuropeptide Y and astrogliosis in the hypothalamus of the adult rat offspring.

The suppression of prolactin production with bromocriptine (BRO) in the last 3 d of lactation reduces milk yield (early weaning) and increases the transfer of leptin through the milk, causing hyperleptinaemia in pups. In adulthood, several changes occur in the offspring as a result of metabolic programming, including overweight, higher visceral fat mass, hypothyroidism, hyperglycaemia, insulin resistance, hyperleptinaemia and central leptin resistance. In the present study, we investigated whether overweight rats programmed by early weaning with maternal BRO treatment have hypothalamic alterations in adulthood. We analysed the expression of neuropeptide Y (NPY), cocaine- and amphetamine-regulated transcript (CART), pro-opiomelanocortin (POMC) and α-melanocyte-stimulating hormone (α-MSH) by immunohistochemistry in the following hypothalamic nuclei: medial and lateral arcuate nucleus (ARC); paraventricular nucleus (PVN); lateral hypothalamus (LH). Additionally, we sought to determine whether these programmed rats exhibited hypothalamic inflammation as indicated by astrogliosis. NPY immunostaining showed a denser NPY-positive fibre network in the ARC and PVN (+82% in both nuclei) of BRO offspring. Regarding the anorexigenic neuropeptides, no difference was found for CART, POMC and α-MSH. The number of astrocytes was higher in all the nuclei of BRO rats. The fibre density of glial fibrillary acidic protein was also increased in both medial and lateral ARC (6·06-fold increase and 9·13-fold increase, respectively), PVN (5·75-fold increase) and LH (2·68-fold increase) of BRO rats. We suggest that early weaning has a long-term effect on the expression of NPY as a consequence of developmental plasticity, and the presence of astrogliosis indicates hypothalamic inflammation that is closely related to overweight and hyperleptinaemia observed in our model.

ErbB receptor-driven prolactinomas respond to targeted lapatinib treatment in female transgenic mice.

As ErbB receptors are expressed in prolactinomas and exhibit downstream effects on prolactin (PRL) production and cell proliferation, we generated transgenic mice using a PRL enhancer/promoter expression system to restrict lactotroph-specific expression of human epidermal growth factor receptor (EGFR) or human EGFR2 (HER2). EGFR or HER2 transgenic mice developed prolactinomas between 13 and 15 months, and confocal immunofluorescence and Western blot analysis confirmed lactotroph-restricted PRL and EGFR or HER2 coexpression. Circulating PRL levels in EGFR and HER2 transgenic mice were increased 5- and 3.8-fold, respectively. Inhibiting EGFR or HER2 signaling with oral lapatinib (100 mg/kg), a dual tyrosine kinase inhibitor for both EGFR and HER2, suppressed circulating PRL by 72% and attenuated tumor PRL expression by 80% and also attenuated downstream tumor EGFR/HER2 signaling. This model demonstrates the role of ErbB receptors underlying prolactinoma tumorigenesis and the feasibility of targeting these receptors for translation to treatment of refractory prolactinomas.

Effect of antiretroviral drugs on prolactin in HIV infected pregnant women

The world has finally settled living with Human immunodeficiency Virus (HIV) with no cure discovered so far. Yong people with HIV infection under HIV management drugs get married and eventually end up being pregnant and bearing babies. The need therefore to investigate the effect of HIV infection and antiretroviral drugs on body chemistry especially the hormones concerned with pregnancy and lactation cannot be over emphasized as this is important to intervene when necessary for the overall benefit for the mother and child. We investigated the effect of anti-retroviral drugs and human immune deficiency virus (HIV) infection on prolactin production and stimulation in HIV-infected pregnant women. A total of 120 subjects participated in the study. Sixty (group 1) of these subjects were HIV seropositive pregnant women who commenced treatment with zidovudine in combination with lamivudine, that is highly anti-retroviral therapy (HAART) at 2nd trimester. The 2nd group made up of 60 HIV seronegative pregnant women who received no drug and as control to the study. The blood samples of both groups were collected at the beginning of the second and at the end of the third trimesters. For group 1 (seropositive pregnant women), the blood collection was done just before commencingthe HAART treatment. The prolactin level of HIV seropositive pregnant women were significantly (P < 0.05) lower than the HIV seronegative pregnant women at the 2nd trimester. Also, the prolactin level of HIV seropositive pregnant women at 2nd trimester was not significantly increased (P> 0.05) compared with third trimester level. The reverse was the case with HIV seronegative pregnant women where prolactin level of 3rdtrimester was significantly increased when compared with 2nd trimester. HIV infection has prolactin suppressive effect on pregnant women and HAART treatment did not significantly raise prolactin level.Keywords: Prolactin, pregnancy, HIV, highly active retroviral therapy (HAART).

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.

Androgen receptor-signalling in the male pituitary is dispensable for normal LH secretion but suppresses prolactin production

Androgen receptor-signalling in the male pituitary is dispensable for normal LH secretion but suppresses prolactin production

Pathogenetic substantiation of the correction of placental dysfunction associated with iron-deficiency anemia

The study aims to investigate the pathogenetic correction of placental dysfunction associated with iron deficiency anemia. It is shown that placental dysfunction associated with iron deficiency is characterized by moderate changes in hormonal profile in the form of reduced production of progesterone and prolactin and placental dysfunction is closely related to manifestations of syderopenic syndrome. The results of multimodality therapy of placental dysfunction in women with iron deficiency anemia have been analysed, the main directions of pathogenesis-based therapies for these patients were determined.

Human decidual stromal cells secrete soluble pro-apoptotic factors during decidualization in a cAMP-dependent manner.

Is there a relationship between decidualization and apoptosis of decidual stromal cells (DSC)? Decidualization triggers the secretion of soluble factors that induce apoptosis in DSC. The differentiation and apoptosis of DSC during decidualization of the receptive decidua are crucial processes for the controlled invasion of trophoblasts in normal pregnancy. Most DSC regress in a time-dependent manner, and their removal is important to provide space for the embryo to grow. However, the mechanism that controls DSC death is poorly understood. The apoptotic response of DSC was analyzed after exposure to different exogenous agents and during decidualization. The apoptotic potential of decidualized DSC supernatants and prolactin (PRL) was also evaluated. DSC lines were established from samples of decidua from first trimester pregnancies. Apoptosis was assayed by flow cytometry. PRL production, as a marker of decidualization, was determined by enzyme-linked immunosorbent assay. DSCs were resistant to a variety of apoptosis-inducing substances. Nevertheless, DSC underwent apoptosis during decidualization in culture, with cAMP being essential for both apoptosis and differentiation. In addition, culture supernatants from decidualized DSC induced apoptosis in undifferentiated DSC, although paradoxically these supernatants decreased the spontaneous apoptosis of decidual lymphocytes. Exogenously added PRL did not induce apoptosis in DSC and an antibody that neutralized the PRL receptor did not decrease the apoptosis induced by supernatants. Further studies are needed to examine the involvement of other soluble factors secreted by decidualized DSC in the induction of apoptosis. The present results indicate that apoptosis of DSC occurs in parallel to differentiation, in response to decidualization signals, with soluble factors secreted by decidualized DSC being responsible for triggering cell death. These studies are relevant in the understanding of how the regression of decidua, a crucial process for successful pregnancy, takes place. This work was supported by the Consejería de Economía, Innovación y Ciencia, Junta de Andalucía (Grant CTS-6183, Proyectos de Investigación de Excelencia 2010 to C.R.-R.) and the Instituto de Salud Carlos III, Ministerio de Economía y Competitividad, Spain (Grants PS09/00339 and PI12/01085 to E.G.O.). E.L.-D. was supported by fellowships from the Ministerio de Educación y Ciencia, Spain and the University of Granada. The authors have no conflict of interest.

Moringa oleifera as a Galactagogue.

Moringa is an herbal galactagogue that has been widely used in the Philippines and some parts of the world. Recent systematic reviews on herbal galactagogues have appraised the use of several herbs but failed to include Moringa. Dr. E. Quisumbing was the first scientist in the Philippines to do a study on its lactogenic properties in 1987. In 1996, Yabes-Almirante and Lim further determined a causal relationship of Moringa capsule intake with increased milk production by demonstrating increased serum prolactin levels. We conducted an update on a previously published systematic review on the use of Moringa compared with placebo in increasing breastmilk production, infant’s weight gain, serum prolactin levels, success of exclusive breastmilk production, and adverse effects. Thirty-three titles and abstracts were retrieved from electronic databases (Medline, HERDIN, Scopus, and Google Scholar), hand searching, and reference tracking. The literature search was limited to human clinical trials using the search terms ‘‘Moringa oleifera,’’ ‘‘Moringa pterygosperma,’’ ‘‘Moringa,’’ ‘‘drumstick tree,’’ ‘‘horseradish tree,’’ and ‘‘Ben oil tree.’’ Six randomized, placebo-controlled, blinded, clinical trials were included in the analyses, five of which were published in the Philippines. All studies were done among Filipinos. Two were done in a community, and four were done in tertiary hospitals. Pooling of studies revealed a significant mean increase in milk volume on Day 7 (Fig. 1) among mothers who received Moringa by 124 mL (95% confidence interval, 90–159 mL; heterogeneity I = 0%; p = 0.32). Milk volume on Days 4 and 5 also favored the Moringa group as well, but the comparison showed significant heterogeneity, probably because of differences in postnatal age of infant, timing of breastmilk collection, and maternal age difference. Of particular interest is the difference in study designs between preterm and term infants. Milk collection for preterm infants involved breastmilk expression either by hand or by machine, and the infants were fed through gavage. For term infants, on the other hand, milk expression and measurement of outcome were done after breastfeeding. This resulted to measurement of residual volume after initial emptying by the baby. The reported milk volume for term infants may therefore be an underestimate. Pooled analysis of the two studies with a total of 73 patients showed a significant increase in the weight of infants during week 4 with a mean difference of 11.9% (95% confidence interval, 5.5–18.2%; heterogeneity I = 0%; p= 0.61), which favors the experimental group. The lactogenic effect of Moringa is hypothesized to be the induction of prolactin production in the anterior pituitary gland. The two studies (Fig. 2) that reported on prolactin levels showed that patients in the Moringa group had higher levels with a statistically significant mean increase of 19.5 · 10 mIU/L (95% confidence interval, 16.8–22.2 · 10 mIU/L; heterogeneity I = 44%; p = 0.18). Timing of outcome measurement is indeed an important variable because growth of infants is dependent on their postnatal age, and prolactin serum levels have varying levels across postpartum days. Safety profile was merely obtained through self-report, of which no adverse event was seen among the six studies. There were no studies that investigated exclusive breastfeeding as an outcome. Overall, these six randomized controlled trials suggest that Moringa can result in a significant increase in breastmilk volume on Day 7. It also results in improvement in the infants’ weight gain. This herbal galactagogue also shows a

Lactogenic Study of the Effect of Ethyl-acetate Fraction of <em>Hibiscus sabdariffa</em> Linn (<em>Malvaceae</em>) Seed on Serum Prolactin Level in Lactating Albino Rats

Lactogenic effect of ethyl acetate fraction of <em>Hibiscus sabdariffa</em> seed was evaluated on serum prolactin and milk production in lactating albino rats. Twenty four lactating rats were grouped randomly at parturition into control, metoclopramide-treated and Ethyl-acetate-treated group consist of six rats in each group (n = 6). The lactating rats were administered control (normal saline), metoclopramide (5 mg/kg) and ethyl-acetate fraction (100 and 200 mg/kg) respectively from day 3-17 of lactation. Milk yield for rats were estimated by pup weight and weight gain. The animals were then euthanized on the day 18 and serum prolactin was analyzed using prolactin kit. The prolactin level of ethyl-acetate fraction of <em>Hibiscus sabdariffa</em> showed a significant increase (p<0.01) when compared to control group. Pup weight gain was also significantly higher (p<0.05) than the control group. This can be deduced that ethyl-acetate fraction of <em>Hibiscus sabdariffa</em> L. seed has lactogenic activity because it increases serum prolactin level and milk production in lactating female albino rats. <em>Hibiscus sabdariffa</em> L. seed stimulate prolactin synthesis; release and milk production in albino rats and it is affordable and safe for consumption.

Prolactin is a potential physiological modulator of swine ovarian follicle function

Apart from the well established role of prolactin (PRL) in the control of mammary development and lactation, this hormone appears to possess a variety of physiological functions and evidence exists about its expression in many extra-pituitary sites.This experimental work was undertaken to gain knowledge about PRL and its receptor presence in the porcine antral follicle. In particular, we investigated the expression and local production of PRL in follicular fluid, theca and granulosa cells cultured in standard conditions and in hypoxia. Then, we also investigated its modulatory effect on several parameters mainly involved in granulosa cell function, namely redox status and steroidogenesis. In order to verify an involvement of PRL in the control of ovarian angiogenesis, a process strictly linked to follicle growth and development, we have verified possible PRL effects on granulosa cell production of Vascular Endothelial Growth Factor (VEGF) and nitric oxide as well as its modulatory role on the angiogenic activity of endothelial cells.Our data demonstrate that in the swine PRL is expressed in both components of the antral follicle, theca and granulosa layers, and it is produced by granulosa cells. Moreover, the hormone represents a relevant modulatory factor on key processes underlying follicular growth and development, such as steroidogenesis and angiogenesis.

1.57 Prolactin is locally produced in the synovium of patients with inflammatory arthritic diseases and promotes macrophage activation

Background and ObjectivesThe sex hormone prolactin (PRL) has immunomodulatory properties, can be produced by immune cells, and elevated PRL serum levels have been reported in rheumatoid arthritis (RA) patients. Here...

Chapter 13 - Hyperprolactinemia and prolactinoma

Prolactinomas are the most frequent pituitary adenomas. In patients with prolactinomas the primary cause of hyperprolactinemia is excessive and autonomic production of prolactin by lactotroph cells. In other conditions, except in case of macroprolactinemia, hyperprolactinemia is secondary to circumstances that stimulate secretion of prolactin by intrinsically normal lactotroph cells, or, rarely, that are the result of decreased clearance of prolactin. In general, cabergoline is the preferred treatment for micro- and macroprolactinomas, because it is more effective with respect to normalization of prolactin levels and reduction of prolactinoma size and because it has fewer side-effects compared to bromocriptine. Recently, it has been suggested that a standardized, individualized, stepwise, dose-escalating regimen of cabergoline may normalize prolactin levels and reduce prolactinoma size in patients who were otherwise considered to be dopamine agonist resistant. In general, the cardiac adverse effects of dopamine agonists reported in Parkinson's disease are not of clinical concern in the treatment of prolactinomas, which are treated with much lower doses. Nonetheless, there is uncertainty with respect to the dose and duration of cabergoline treatment, which requires echocardiographic follow-up. Although withdrawal of dopamine agonists may be considered in patients with prolactinomas well controlled by dopamine agonists, especially in postmenopausal women, recurrence of signs and symptoms may occur in a considerable portion of patients.

The Role of Exchange Protein Directly Activated by Cyclic AMP 2-mediated Calreticulin Expression in the Decidualization of Human Endometrial Stromal Cells

Decidualization of human endometrial stromal cells (ESCs) accompanied by the production of prolactin (PRL) and IGF-binding protein (IGFBP) 1 and rounded-cell morphology is indispensable for the establishment and maintenance of pregnancy. Protein kinase A (PKA)-mediated cAMP signaling is known to be crucial for decidualization. We previously reported that activation of a cAMP mediator, called Exchange protein directly activated by cAMP (EPAC) promotes cAMP analog- or ovarian steroid-induced decidualization in cultured human ESCs. In addition, small interfering RNA-mediated knock-down of the EPAC subtypes, EPAC1 or EPAC2, or knock-down of Rap1, a downstream factor of EPAC signaling, blocked functional and morphological decidualization of ESCs. However, factors downstream of EPAC2 other than Rap1 have not been determined. The present study was undertaken to identify additional downstream targets of EPAC2 associated with decidualization. Using proteomic analysis, we identified calreticulin (CRT) as a potential target of EPAC2. Knock-down of CRT expression in cultured ESCs significantly inhibited PKA-selective cAMP analog- or PKA-selective cAMP analog plus EPAC-selective cAMP analog-induced PRL and IGFBP1 expression. Furthermore, CRT knock-down suppressed the ovarian steroid-stimulated PRL and IGFBP1 expression and morphological differentiation, and silencing of EPAC2 or CRT significantly increased senescence-associated β-galactosidase activity with enhanced p21 expression and decreased p53 expression. These results suggest that EPAC2 and CRT are associated with cellular senescence in ESCs. In conclusion, we demonstrate here that EPAC2-mediated CRT expression is essential for the functional and morphological differentiation of ESCs into decidual cells. Furthermore, both EPAC2 and CRT might prevent ESCs from undergoing abnormal cellular senescence during decidualization.

Effect of hypo-osmotic environmental changes on the expression of gonadotropin-releasing hormone, its receptor, and gonadotropin hormone subunit mRNA in adult chum salmon (Oncorhynchus keta)

Migrating fish such as salmonids are affected by external environmental factors and salinity changes are particularly important, influencing spawning migration. The aim of this study was to test whether changes in salinity would affect the expression of the hypothalamic-pituitary-gonadal (HPG) axis hormones (gonadotropin-releasing hormones (GnRHs) [salmon GnRH and chicken GnRH-II], GnRH receptors [GnRHR1 and GnRHR5], and mRNA of the gonadotropin hormone [GTH] subunits [GTHα, follicle stimulating hormone β, and luteinizing hormone β]) in chum salmon (Oncorhynchus keta). Fish were progressively transferred from seawater (SW) through 50% SW to freshwater (FW), and the relationship between the osmoregulatory hormone prolactin (PRL) and sexual maturation was determined. The expression and activity of HPG hormones and their receptors, and levels of estradiol-17β and PRL increased after fish were transferred to FW, demonstrating that changes in salinity stimulate the HPG axis and PRL production in migrating chum salmon. These findings reveal details about the role of the endocrine system in maintaining homeostasis and stimulating sexual maturation and reproduction in response to salinity changes in this species.

Premature menopause secondary to Rathke’s pouch cyst

<p style="margin-bottom: 0in;"><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow,sans-serif;"><span style="font-size: x-small;">A 35 year old female presented with 6 years of amenorrhoea with a background history of menstrual irregularity preceding the amenorrhoea. She was treated as polycystic ovarian syndrome (PCOS) but finally found to have a very large pituitary lesion. This was originally thought to be a non-functioning pituitary adenoma, however intraoperative findings suggest the lesion was likely a Rathke’s cleft cyst, a relatively rare sellar mass whose hormonal effects were secondary to compression of normal pituitary tissue. Interestingly despite definitive resection and stabilisation of lactotrophs and gonadotroph levels our patient continued to have hypogondotrophic hypogonadism and finally required a hysterectomy for the safe initiation of HRT.</span></span></span> <p style="margin-bottom: 0in;"><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow-BoldOblique,sans-serif;"><span style="font-size: x-small;"><em><strong>Background: </strong></em></span></span></span><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow,sans-serif;"><span style="font-size: x-small;">Pituitary pathology accounts for 19% of secondary amenorrhoea. Because menstrual disturbances are a large part of the workload in gynaecology it is important for gynaecologists to have an understanding of pituitary aetiologies for amenorrhoea. As well as secondary amenorrhoea, pituitary pathologies can also mimic other gynaecological conditions such as polycystic ovarian syndrome and primary ovarian failure. It is important to consider the pituitary gland as a cause.</span></span></span> <p style="margin-bottom: 0in;"><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow,sans-serif;"><span style="font-size: x-small;">Gynaecologists are in a good position to recognise the presentation of many pituitary lesions. Approximately 1 in 3 pituitary adenomas are prolactinomas, making it the most common form of pituitary adenoma. High serum prolactin presents with subfertility, oligomenorrhoea or amenorrhoea, and interestingly, least commonly with galactorrhoea. Many of these symptoms would promote a referral to gynaecology. Other pituitary lesions can also present with these same symptoms purely by mass effect and compression of the pituitary stalk. Stalk compression causes decreased negative feedback by dopamine on prolactin production leading to hyperprolactinaemia. Therefore, the most common presentation of pituitary macroadenomas, both hormone secreting and non-functioning, are also menstrual and fertility dysfunction.</span></span></span> <p style="margin-bottom: 0in;"><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow,sans-serif;"><span style="font-size: x-small;">The mass effect caused by pituitary lesions is not limited to pituitary adenomas. Rarer lesions include craniopharyngiomas, meningiomas, malignant tumours, hypophsitis and Rathke's cleft cysts. The case I would like to put forward is of particular interest as our case study was found to have a large pituitary lesion which was thought to be a Rathke's cleft cyst, a relatively rare sellar mass, whose hormonal effects were all secondary to compression of normal pituitary tissue. Interestingly despite resection of the lesion our patient continued to have amenorrhea secondary to pituitary tissue damage. She illustrates the strong link between gynaecological symptoms and pituitary and sellar pathology, and is a rare and interesting learning case.</span></span></span> <p style="margin-bottom: 0in;"><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow,sans-serif;"><span style="font-size: x-small;">DOI: <a href="http://dx.doi.org/10.4038/sljog.v35i2.6163">http://dx.doi.org/10.4038/sljog.v35i2.6163</a></span></span></span> <p style="margin-bottom: 0in;"><span style="color: #231f20;"><span style="font-family: Helvetica-Narrow-Bold,sans-serif;"><span style="font-size: x-small;"><em><span style="font-weight: normal;">Sri Lanka Journal of Obstetrics and Gynaecology</span></em><strong> </strong><span style="font-family: Helvetica-Narrow,sans-serif;">2013; 35: 65-66</span></span></span></span>

Abstract B006: Tumor cell heterogeneity of prolactin-induced ERα+ mammary carcinomas

Abstract Anti-estrogenic therapies have significantly improved the survival of women with estrogen-receptor alpha (ERα) positive breast tumors. Unfortunately 25% of women who suffer from ERα+ cancer experience recurrence of tumors which can exhibit strong therapeutic resistance. The mechanisms underlying the onset of anti-estrogen resistant tumors following treatment are not well understood, but emerging evidence is now implicating tumor-initiating cells (TICs) in tumor growth, treatment resistance, and differentiation. TICs represent a small discrete subpopulation of cells which have the ability to drive the growth of an entire heterogeneous tumor. Elevated circulating prolactin (PRL) levels have been shown to be associated with ERα+ breast tumor incidence, and also correlate with increased metastasis and treatment resistance. To examine the relationship between TICs and treatment resistance in ERα+ mammary carcinomas, we utilized a transgenic mouse model (NRL-PRL), established on a FVB/N background, that mimics the local expression of PRL within the mammary epithelia as observed in women. After a long latency, nulliparous NRL-PRL females develop locally invasive mammary carcinomas, with some observed lung and bone metastases. Importantly, PRL-induced mammary tumors exhibit wide histological diversity and the majority are ERα+ (&amp;gt;75% of tumors). Although development of tumors is accelerated by supplemental estrogen, end stage tumors are insensitive to estrogen, similar to the luminal B subtype. A panel of 20 ERα+ glandular and papillary adenocarcinomas was collected from NRL-PRL females. Their histological appearances and ERα expression were retained after transplantation into mammary glands of wild-type syngeneic recipients. To analyze tumor cell heterogeneity, subpopulations were characterized by subjecting enzymatically dispersed tumor cells to fluorescence-activated cell sorting (FACS). PRL-induced ERα+ tumors consistently displayed high percentages of both luminal (EPCAMhiCD49fmed) and basal (EPCAMloCD49fhi) cells, which is distinct from the luminal but ERα- (MMTV-Her2/neu) and claudin-low (p53-/-) mouse models of breast cancer. The luminal/basal cell ratios for NRL-PRL, MMTV-Her2/neu, and p53-/- derived tumors were 2.4±0.4, 46.0±1.8, and 0.004±0.005, (mean±S.D., N=3-4), respectively. The basal compartment exhibits relatively high TIC enrichment in several well-characterized models of breast cancer. However, recent evidence suggests that the luminal compartment may contain a luminal-progenitor subpopulation which also displays some TIC activity. Interestingly, expression of the surface-marker CD61 in PRL-induced tumors was distributed across both luminal and basal cell compartments. Ongoing limiting-dilution transplantation studies will identify fractions containing TIC activity. Transgenic mammary production of PRL is a useful mouse model to study aggressive ERα+ breast cancer that will provide novel insights into this disease. Supported by R01 CA157675 and T32 ES007015. Citation Format: Michael P. Shea, Kathleen A. O'Leary, Linda A. Schuler. Tumor cell heterogeneity of prolactin-induced ERα+ mammary carcinomas. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B006.

Completely Humanizing Prolactin Rescues Infertility in Prolactin Knockout Mice and Leads to Human Prolactin Expression in Extrapituitary Mouse Tissues

A variety of fundamental differences have evolved in the physiology of the human and rodent prolactin (PRL) systems. The PRL gene in humans and other primates contains an alternative promoter, 5.8 kbp upstream of the pituitary transcription start site, which drives expression of PRL in "extrapituitary" tissues, where PRL is believed to exert local, or paracrine, actions. Several of these extrapituitary PRL tissues serve a reproductive function (eg, mammary gland, decidua, prostate, etc), consistent with the hypothesis that local PRL production may be involved in, and required for, normal reproductive physiology in primates. Rodent research models have generated significant findings regarding the role of PRL in reproduction. Specifically, disruption (knockout) of either the PRL gene or its receptor causes profound female reproductive defects at several levels (ovaries, preimplantation endometrium, mammary glands). However, the rodent PRL gene differs significantly from the human, most notably lacking the alternative promoter. Understanding of the physiological regulation and function of extrapituitary PRL has been limited by the absence of a readily accessible experimental model, because the rodent PRL gene does not contain the alternative promoter. To overcome these limitations, we have generated mice that have been "humanized" with regard to the structural gene and tissue expression of PRL. Here, we present the characterization of these animals, demonstrating that the human PRL transgene is responsive to known physiological regulators both in vitro and in vivo. More importantly, the expression of the human PRL transgene is able to rescue the reproductive defects observed in mouse PRL knockout (mPRL(-)) females, validating their usefulness in studying the function or regulation of this hormone in a manner that is relevant to human physiology.

Treatment of pituitary prolactinoma reverses unresponsiveness to PDE5 inhibitor therapy in men with ED and SHPRL

Treatment of pituitary prolactinoma reverses unresponsiveness to PDE5 inhibitor therapy in men with ED and SHPRL

Effects of running wheel training on adult obese rats programmed by maternal prolactin inhibition

The inhibition of maternal prolactin production in late lactation leads to metabolic syndrome and hypothyroidism in adult offspring. Physical training is a therapeutic strategy that could prevent or reverse this condition. We evaluated the effects of a short-duration low-intensity running wheel training program on the metabolic and hormonal alterations in rats. Lactating Wistar rats were treated with bromocriptine (Bro, 1 mg twice a day) or saline on days 19, 20, and 21 of lactation, and the training of offspring began at 35 days of age. Offspring were divided into sedentary and trained controls (C-Sed and C-Ex) and sedentary and trained Bro-treated rats (Bro-Sed and Bro-Ex). Chronic exercise delayed the onset of weight gain in Bro-Ex offspring, and the food intake did not change during the experimental period. At 180 days, visceral fat mass was higher (+46%) in the Bro-Sed offspring than in C-Sed and Bro-Ex rats. As expected, running capacity was higher in trained animals. Most parameters observed in the Bro-Sed offspring were consistent with hypothyroidism and metabolic syndrome and were reversed in the Bro-Ex group. Chronic exercise did not influence the muscle glycogen in the C-Ex group; however, liver glycogen was higher (+30%) in C-Ex group and was unchanged in both Bro offspring groups. Bro-Ex animals had higher plasma lactate dehydrogenase levels, indicating skeletal muscle damage and intolerance of the training program. Low-intensity chronic training is able to normalize many clinical aspects in Bro animals; however, these animals might have had a lower threshold for exercise adaptation than the control rats.

STAT5 and Prolactin Participate in a Positive Autocrine Feedback Loop That Promotes Angiogenesis

We have shown previously that the murine prolactin/growth hormone family member proliferin plays a pivotal role in angiogenesis induced by the FGF2/STAT5 signaling cascade. To delineate the signaling pathway downstream of STAT5 in the human system, where proliferin does not exist, we expressed constitutively active (CA) or dominant-negative (DN) mutant STAT5A in hCMEC/D3 human brain endothelial cells. We found that conditioned medium from CA-STAT5A- but not from DN-STAT5A-overexpressing endothelial cells (EC) is sufficient to induce EC migration and tube formation but not proliferation, indicating that STAT5A regulates the secretion of autocrine proangiogenic factors. We identified prolactin (PRL) as a candidate autocrine factor. CA-STAT5A expression stimulates PRL production at the RNA and protein level, and STAT5A binds to the PRL promoter region, suggesting direct transcriptional regulation. Medium conditioned by CA-STAT5A-overexpressing EC induces phosphorylation of the PRL receptor and activates MAPK. Knockdown of PRL expression by shRNA or blocking of PRL activity with neutralizing antibodies removed the CA-STAT5A-dependent proangiogenic activity from the conditioned medium of EC. The addition of recombinant PRL restores this activity. STAT5A-induced PRL in the conditioned medium can activate STAT5, STAT1, and to a lesser extent STAT3 in hCMEC/D3 cells, suggesting the existence of a positive feedback loop between STAT5 and PRL that promotes angiogenesis. Furthermore, we find that VEGF, a potent proangiogenic factor, is induced by activation of STAT5A, and VEGF induction depends on PRL expression. These observations demonstrate a STAT5/PRL/VEGF signaling cascade in human brain EC and implicate PRL and VEGF as autocrine regulators of EC migration, invasion, and tube formation.