Bioinformatic searching on the zebrafish genome indicates that there are five members of this hormone family (namely GH, SLalpha, SLbeta, PRL1 and PRL2) and four receptors (namely GHR1, GHR2, PRLR1 and PRLR2). However, it should be noted that these ligands and receptors are only named according to their sequence homology with those in other species. There is so far no systematic study to unravel the relationship among the ligands and receptors. The last point is particularly relevant as some of the ligands and receptors are duplicated in the fish genome. In addition, there is much controversy regarding whether one of the two GHRs is in fact the receptor for SL. A systematic study on the interaction among the ligands and receptors in zebrafish would help to resolve these issues. / In fish, growth hormone (GH), prolactin (PRL) and somatolactin (SL) are members of a gene family of polypeptide hormones which share homology in protein sequence and structure. To date, numerous functions have been attributed to this family of hormones such as growth, immune response, protein metabolism and ion regulation. The biological functions of GHlPRL are mediated through binding of the ligands on their respective receptors. It is believed that this gene family arose as the result of multiple gene duplications and subsequent divergent evolution, co-evolving with their corresponding receptors. Despite the above mentioned similarities in their structures, their cognate receptors and their signaling mechanisms, important differences among this gene family of polypeptide hormones can be recognized in their biological functions. / In the present study, the luciferase reporter assay, His-tag pulldown assay and signaling pathway activation were employed to investigate the interaction among the ligands and their receptors. It was shown that recombinant zebrafish GH, PRLI and PRL2 could only interact with their cognate receptors, i.e. GHRl, GHR2, PRLRI and PRLR2 respectively. In comparison, zebrafish SLalpha and SLbeta could neither interact with GHR1, GHR2, PRLR1 and PRLR2 in the binding study, nor could these two SLs activate the receptor-mediated downstream signaling and transcriptional activities of the four receptors in zebrafish. These data argue against the hypothesis that GHRI is the SL receptor. / The role of PRLR in early development of zebrafish was also explored. Whole mount in situ hybridization (WISH) study showed that PRLR1 was mainly expressed in the pancreas and pronephric duct, while PRLR2 was expressed in the pronephric duct only. In the PRLR1 morpholino (MO) knockdown embryos, the yolk extension (YE), the formation of which was reported to be associated with pronephric duct development, disappeared at 24 hours post fertilization. This phenotype could not be observed in the PRLR2 MO knockdown or control embryos. Real time quantitative RT-PCR and WISH data revealed that several genes expressed in the pronephric duct were up or down-regulated. The protein expression pattern of pronephric duct marker atplal was also affected in the embryos injected with PRLRI MO. In addition, histological studies showed that structure of the pronephric duct was destroyed in the PRLRI MO embryos. These results suggest that PRLRI plays an important role in the development of the pronephric duct in zebrafish embryos. / Chen, Mingliang. / "October 2010." / Adviser: Cheung Wing-Tai. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 140-179). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

INTRODUÇÃO: A prolactina é um hormônio polipeptídico, que possui reconhecida ação sistêmica, principalmente na fisiologia da reprodução, porém, seu desequilíbrio, em especial a hiperprolactinemia, é cada vez mais frequente na prática clínica. Apesar de ser um distúrbio relativamente comum, ainda existem dúvidas quanto aos efeitos moleculares da hiperprolactinemia no trato genital, particularmente no útero, e também na hipófise. O presente estudo teve por objetivo verificar os efeitos da hiperprolactinemia induzida pela metoclopramida na expressão gênica da prolactina e de seus receptores no útero e na hipófise de camundongo fêmea. MÉTODOS: Utilizaram-se 49 camundongos fêmeas (Wistar), randomicamente divididas em 7 grupos contendo 7 animais cada: 1) SS não ovariectomizadas que receberam solução salina (veículo); 2) M não ovariectomizadas tratadas com metoclopramida; 3) OSS ovariectomizadas tratadas com solução salina (veículo); 4) OM ovariectomizadas tratadas com metoclopramida; 5) OME ovariectomizadas tratadas com metoclopramida e 17-estradiol; 6) OMP ovariectomizadas tratadas com metoclopramida e progesterona micronizada; 7) OMEP ovariectomizadas tratadas com metoclopramida, 17-estradiol e progesterona micronizada. Após 50 dias os animais foram sacrificados sendo retirados o útero e a hipófise de cada animal para extração do ácido ribonucleico total, que foi utilizado para a síntese de ácido desoxirribonucleico complementar e avaliação da expressão gênica da prolactina e das diferentes isoformas de seus receptores, por reação em cadeia da polimerase em tempo real. RESULTADOS: Na hipófise, em animais não ovariectomizados, o tratamento com metoclopramida aumentou a expressão do gene que codifica a prolactina em relação ao tratamento apenas com o veículo. Nos animais castrados, a progesterona isoladamente ou associada ao estrogênio determinou o incremento do RNA mensageiro da prolactina em relação aos outros animais castrados que receberam outras combinações de tratamento. Este efeito foi semelhante ao da metoclopramida em animais com os ovários intactos. Em relação ao receptor de prolactina, o estrogênio e a progesterona, isoladamente, foram responsáveis pelo incremento da isoforma S2. No útero houve aumento na expressão de RNA mensageiro de prolactina após tratamento com metoclopramida ou com tratamento isolado ou combinado de estrogênio e progesterona. A ovariectomia determinou a redução da expressão das isoformas S1 e S2 do receptor de prolactina de todas as isoformas estudadas. Já o tratamento estroprogestativo determinou elevação da formas S3 e L do receptor, enquanto com a progesterona isoladamente causou apenas o incremento da forma L do receptor da prolactina no útero dos animais castrados. CONCLUSÕES: Nossos dados sugerem que o tratamento com metoclopramida altera de forma diferente a expressão de prolactina e de seus receptores quando se compara o resultado da hipófise em relação ao útero em camundongos fêmeas castrados e tratados com esteróides sexuais / INTRODUCTION: Prolactin is a polypeptide hormone with a recognized systemic action mainly on reproductive physiology. However, prolactin imbalance, particularly hyperprolactinemia, is increasingly more frequent in clinical practice. Although it is a comparatively common disorder, there are still doubts about the molecular effects of hyperprolactinemia on the genital tract especially in the uterus and the pituitary. The present study aimed at verifying the effects of metoclopramide-induced hyperprolactinemia on the gene expression of prolactin and its receptors in the uterus and pituitary of the female mouse. METHODS: Forty-nine female Wistar mice were randomized to 7 equal-sized groups as follows: 1) SS nonoophorectomized mice treated with saline solution (vehicle); 2) M nonoophorectomized mice treated with metoclopramide; 3) OSS oophorectomized mice treated with saline solution (vehicle); 4) OM oophorectomized mice treated with metoclopramide; 5) OME oophorectomized mice treated with metoclopramide and 17-estradiol; 6) OMP oophorectomized mice treated with metoclopramide and micronized progesterone; 7) OMEP oophorectomized mice treated with metoclopramide, 17-estradiol, and micronized progesterone. The animals were sacrificed 50 days after the end of the treatment, and the uterus and pituitary of each animal were removed for extraction of total ribonucleic acid, which was then used for synthesizing complementary deoxyribonucleic acid and for evaluating the gene expression of prolactin and the different isoforms of its receptors by the real-time polymerase chain reaction. RESULTS: In the pituitary of the nonoophorectomized mice, the treatment with metoclopramide against that with vehicle alone increased the expression of the prolactin-encoding gene. In the castrated animals, progesterone by itself or in conjunction with estrogen determined a raise in prolactin messenger RNA as opposed to the two other treatments with different combinations. This effect was similar to that produced by metoclopramide in animals with intact ovaries. Estrogen and progesterone, acting independently of each other, were responsible for the increase in the S2 isoform of the prolactin receptor. In the uterus, there was heightened expression of prolactin messenger RNA under the effect of the treatment with metoclopramide or with estrogen and/or progesterone. Oophorectomy caused a greater reduction in expression of the prolactin receptor S1 and S2 isoforms than in the other isoforms. However, the combined estrogen plus progesterone treatment led to an increase in the S3 and L forms of the receptor, while progesterone alone resulted solely in a higher expression of the L form of the prolactin receptor in the endometrium of the castrated mice. CONCLUSION: Our data suggest that metoclopramide treatment induces different changes in the expression of prolactin and its receptors according to whether the effect occurs in the pituitary or the uterus of castrated female mice treated with sex steroids

A macroprolactinemia é condição freqüente na hiperprolactinemia e em geral, sem impacto clínico. Os dados sobre a atividade biológica da macroprolactina (bbPRL) são controversos e baseados em bioensaio heterólogo com células de rato Nb2. A atividade biológica da bbPRL é observada in vitro e não in vivo, provavelmente porque seu alto peso molecular evita sua passagem pelos capilares. A bioatividade da bbPRL talvez varie de acordo com a especificidade do receptor de prolactina (PRLR). Avaliamos a bioatividade da bbPRL de indivíduos macroprolactinêmicos (Grupo I, n = 18) e da PRL monomérica (mPRL) de pacientes hiperprolactinêmicos sem bbPRL (Grupo II, n = 5) em Nb2 e em células Ba/F-LLP, transfectadas com o PRLR humano. Enquanto ambos ensaios apresentam resultados similares para a atividade de mPRL, nossos resultados indicam que a atividade da bbPRL é presente em ensaio heterólogo e não em ensaio homólogo. O ensaio Ba/F-LLP é sensível e apresenta melhor correlação com a atividade in vivo da bbPRL / Macroprolactinemia is a frequent finding in hyperprolactinemic individuals, usually without clinical impact. Data on biological activity of macroprolactin (bbPRL) is mostly based on a heterologous bioassay (Nb2 cell). Biological activity of bbPRL observed in vitro but not in vivo maybe due to its high molecular weight preventing its passage through capillary barrier. Alternatively, bbPRL bioactivity may differ depending on the PRL receptor species specificity. BbPRL from macroprolactinemic individuals and monomeric PRL (mPRL) from hyperprolactinemic patients without macroprolactinemia were tested in two bioassays: Nb2 and in Ba/F-LLP, which expresses human prolactin receptor. While both bioassays achieve similar results considering mPRL activity, our results indicate that bbPRL displays activity in a heterologous but not in a homologous bioassay, consistently with the apparent absence of bbPRL bioactivity in vivo

Atualmente, é crescente o interesse em estudar o potencial do Sistema Nervoso Central (SNC) como alvo de medicamentos antidiabéticos, uma vez que ele possui receptores de insulina e desempenha papel crítico na regulação da homeostase glicêmica. Nesse sentido, o Cycloset® (mesilato de bromocriptina de liberação rápida), um medicamento de ação central aprovado nos Estados Unidos para o tratamento do DMT2, atende a essa tendência atual. Trabalhos prévios mostram efeitos benéficos da bromocriptina (Bromo) sobre a hiperglicemia e hiperlipidemia em modelos de animais obesos tratados com essa droga. Por ser um agonista dopaminérgico, um dos possíveis mecanismos de ação dessa droga pode ser bloqueando a liberação e produção de prolactina (Prl). Níveis elevados de prolactina na circulação sanguínea, observados tanto em indivíduos com prolactinomas como em pessoas tratadas com medicamentos que causam hiperprolactinemia, geram anormalidades no metabolismo de carboidratos e lipídeos, o que pode levar a um quadro de síndrome metabólica. Na presente tese, testamos a hipótese de que ao menos parte dos efeitos antidiabéticos da Bromo seja mediada pela inibição da secreção de prolactina. Avaliamos os efeitos do tratamento com Bromo em camundongos machos e fêmeas geneticamente obesos e resistentes à insulina (ob/ob), bem como testamos se os efeitos benéficos do medicamento seriam revertidos com a reposição de Prl. Machos tratados com Bromo apresentaram maior sensibilidade à insulina, enquanto que a reposição de Prl manteve os animais menos sensíveis, tais como os animais do grupo controle. As fêmeas tratadas com Bromo apresentaram tendência à melhora de sensibilidade à insulina, bem como foram mais tolerantes à glicose, sendo que a reposição de Prl em animais tratados com Bromo também reverteu o efeito benéfico do medicamento. Dessa forma, demonstramos que ao menos parte dos efeitos antidiabéticos da Bromo é mediada pela inibição da secreção basal de Prl. Em um segundo conjunto de experimentos, testamos se a administração de antagonistas de prolactina (G129R-hPrlR) em machos ob/ob, por vias centrais ou periféricas, produziria efeito antidiabético. Observamos que tanto o tratamento periférico como o central diminui a curva glicêmica dos animais em testes de tolerância à glicose e melhoram a sensibilidade à insulina, embora ainda não tenhamos obtido valores significativos devido a nossa amostragem. Por fim, investigamos se a ação da Prl sobre o metabolismo ocorre por meio da interação com o receptor de estrógeno alfa (ERα). Verificamos que receptores de prolactina e de ERα são expressos em áreas comuns no SNC e que variações nos níveis circulantes de estrógeno causam mudanças na sensibilidade à prolactina. Portanto, no presente trabalho, identificamos o possível mecanismo pelo qual a Bromocriptina promove melhorias no controle glicêmico e, de forma inédita, produzimos evidências que o uso de antagonistas de prolactina pode ter potencial no tratamento do DMT2. / Type 2 Diabetes mellitus (T2DM) is a syndrome characterized by dysfunctions in the metabolism of glucose, amino acids and free fat acids. Although most of the drugs currently used to treat T2DM targets peripheral organs, a growing interest in studying the Central Nervous System (CNS) as a potential target of antidiabetic drugs is appearing. The CNS possesses insulin receptors and plays a critical role in regulating glucose homeostasis. In this sense, Cycloset® (quick release bromocriptine mesylate) a drug that acts on CNS, was recently approved in United States to treat T2DM. Previous studies have shown beneficial effects of bromocriptine (Bromo) on hyperglycemia and hyperlipidemia in obese animal models. As a dopaminergic agonist, a possible mechanism of action of this drug could be caused by a decreased prolactin (Prl) production and release. High serum prolactin levels, as observed in patients bearing prolactinomas or individuals using drugs that induce hyperprolactinemia, generate abnormalities in carbohydrate and lipid metabolism, which can lead to metabolic syndrome. In the current thesis, we tested the hypothesis that part of bromocriptine antidiabetic effects is due to an inhibition of prolactin secretion. We evaluated Bromo effects in genetically obese and insulin resistant male and female mouse (ob/ob), as well as we tested whether replacing Prl could reverse the beneficial effects of Bromo. Males treated with Bromo showed lower insulin resistence, whereas Prl replacement decreased insulin sensitivity. Females treated with Bromo showed tendency towards an improvement in their insulin sensitivity and glucose tolerance. Prl replacement also reversed the beneficial effects of Bromo in this group. Thus, we demonstrated that at least part of the antidiabetic effects of Bromo is due to inhibition of Prl secretion. In another set of experiments, we tested whether central or peripheral treatment with prolactin antagonists (G129R-hPrlR) causes antidiabetic effects in ob/ob male mice. Both peripheral and central treatment decreased the glycemic curve during glucose and insulin tolerance tests, although we still did not obtain statistically significant values with our sample size. Lastly, we investigated whether metabolic Prl action occurs due to a putative interaction with estrogen receptor alpha (ERα). We found a wide co-expression between Prl receptor and ERα in the CNS. Additionally, changes in estrogen levels decrease prolactin sensitivity. Therefore, in the present study we identified the possible mechanism by which bromocriptine promotes improvements in glycemic control, and for the first time, we obtained evidence that the use of prolactin antagonists can have a potential effect in the treatment of T2DM.

Genetic predisposition and exposure to alcohol and stress increase the risk for alcoholism, possibly by forming a threefold interaction. This is suggested by various aspects of alcohol-induced stress response dampening in offspring of alcoholics. We tested whether such an interaction is also revealed by prolactin secretion, which is predominantly controlled by hypothalamic dopamine. Plasma prolactin was measured during four experimental days in 26 young males with a paternal history of alcoholism (PHA) and in 22 family history negative (FHN) controls. A public speaking stress paradigm was applied on the first 2 days, and a non-stress acoustic startle experiment on the others. Before the tests, subjects drank alcohol (0.6 g/kg) or placebo in a randomized, double-blind crossover design. During placebo experiments, prolactin levels significantly increased after stress, but not after startle, and did not differ between risk groups. Alcohol administration significantly increased prolactin before stress and during startle in both groups, did not alter stress-induced prolactin stimulation in FHN, but significantly attenuated the prolactin stress response in PHA subjects. The alcohol effects on prolactin, cortisol, and adrenocorticotropin stress response were positively interrelated with each other. These data confirm that alcohol specifically dampens the stress response in PHA but not FHN subjects. Since prolactin responses to stress alone and alcohol alone were normal in PHA, we conclude that this genetic effect is not related to altered physiology of the hypothalamic dopaminergic system, but to risk-group specific alcohol effects on hierarchically higher brain areas controlling the stress response in general.

The control of prolactin secretion is a complex interaction of peptides and neurotransmitters acting either in an inhibitory or stimulating way to effect final secretion of this hormone from the lactotrope cell in the anterior hypothalamus. These factors may act either directly on the lactotrope cell or indirectly by changing either dopamine restraint of prolactin secretion or by modulating peptide substances or neurotransmitters higher up in the hypothalamus. Gonadal steroids may also modulate the effect of peptides or dopamine at the level of the lactotrope. Prolactin's major role in the female rat is one of milk production post - partum, nurturing the young. It probably also has other physiological functions and may play a part in the menstrual cycle although this is controversial. Certainly, pulsatile secretion of prolactin during the menstrual cycle is well established and in the luteal phase this is concomitant with the secretion of luteinizing hormone. Theories explaining the synchronous surges seen during this phase of the menstrual cycle have been proposed and GnRH has been implicated in the genesis of the concordance of these secretory spikes. Using a potent GnRH antagonist an experiment was undertaken to establish the role of GnRH by blocking this hypothalamic peptide and observing the effect that this had on luteinizing hormone, prolactin and follicle stimulating hormone. In the first part of the thesis the control of prolactin secretion is reviewed. In the following section, an experiment was performed using a potent GnRH antagonist. A dose response curve was established for the antagonist action on LH. Then a twice maximum dose of this peptide was administered to three subjects in the midluteal phase of the menstrual cycle and the response of LH, prolactin and FSH was measured. The results indicate that although the GnRH antagonist significantly blocked LH secretory peaks, this action was not observed for either prolactin or FSH. This result is perhaps at variance with previous data which suggested that GnRH was responsible for concordant secretory spikes of LH and prolactin in the midluteal phase of the menstrual cycle.

published_or_final_version / abstract / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

8 Abstract Introduction: Celiac disease is indentified as the loss of oral tolerance to gluten, it is an organ-specific autoimmune disease in which both, adaptive and innate immunity participate. Monocytes are important part of immune system; they have many functions and express very diverse membrane receptors including Toll-like receptors (TLRs). TLRs are involved in the innate immune response, specifically TLR2 and TLR4 are crucial for recognition of bacterial components and TLR7 recognizes virus's ssRNA. Monocytes also produce prolaktin (PRL), which acts as a cytokine that modulates immune responses. To clarify the role of innate immunity and circulating monocytes in pathogenesis of celiac disease, we focused on changes in expression of selected Toll-like receptors (TLR2, TLR4, TLR7), prolactin, some pro- a anti-inflammatory cytokines (TNF-α, IL-6, IL-12, IL-10). We monitored the influence of the SNP - 1149 G/T on the expression of PRL mRNA. Another objective of this work was the introduction and optimization of in vitro methods for cultivation and stimulation of peripheral monocytes. Material and Methods: This pilot study includes 21 patients with celiac disease and 40 healthy controls. For determination of mRNA levels of the studied genes we isolated RNA from monocytes that were isolated by...

Introduction: Diabetes mellitus is a polygenic disease and its development is influenced to some extent by environmental factors as well. Innate immunity triggers nonspecifically first defense reactions after penetration of the pathogen into the body, while overstimulation components of innate immunity may give rise to autoimmune diseases, including diabetes type 1. The components of innate immunity are, among others, Toll-like receptors (TLRs) belonging to a group of the structures recognizing preserved molecular structures characteristic of pathogens. Toll-like receptors are abundantly expressed by monocytes which produce prolactin (PRL) having an immunostimulatory function. To clarify the role of innate immunity in the pathogenesis of diabetes, we focused on the expression of mRNA and protein expression of TLR2 and TLR4. The expression of PRL was studied only at the level of mRNA. Monocytes were separated by flow cytometry into classical (CD14++) and nonclassical (CD14+). We monitored their percentages and the degree of expression of CD14 antigen on their surface.The operational objective of this dissertation was to optimize the stimulation of monocytes for the planned study of the function of non-pituitary prolactin in vitro and determine the appropriateness of the use of healthy donors' buffy...