RESUMO
Previous work suggests that larvae from Sydney rock oysters that have been selectively bred for fast growth and disease resistance are more resilient to the impacts of ocean acidification than nonselected, wild-type oysters. In this study, we used proteomics to investigate the molecular differences between oyster populations in adult Sydney rock oysters and to identify whether these form the basis for observations seen in larvae. Adult oysters from a selective breeding line (B2) and nonselected wild types (WT) were exposed for 4 weeks to elevated pCO2 (856 µatm) before their proteomes were compared to those of oysters held under ambient conditions (375 µatm pCO2 ). Exposure to elevated pCO2 resulted in substantial changes in the proteomes of oysters from both the selectively bred and wild-type populations. When biological functions were assigned, these differential proteins fell into five broad, potentially interrelated categories of subcellular functions, in both oyster populations. These functional categories were energy production, cellular stress responses, the cytoskeleton, protein synthesis and cell signalling. In the wild-type population, proteins were predominantly upregulated. However, unexpectedly, these cellular systems were downregulated in the selectively bred oyster population, indicating cellular dysfunction. We argue that this reflects a trade-off, whereby an adaptive capacity for enhanced mitochondrial energy production in the selectively bred population may help to protect larvae from the effects of elevated CO2 , whilst being deleterious to adult oysters.
Assuntos
Dióxido de Carbono/análise , Ostreidae/genética , Proteoma/genética , Poluentes Químicos da Água/análise , Animais , Aquicultura , Cruzamento , Monitoramento Ambiental/métodosRESUMO
BACKGROUND: The thyroid hormone derivative 3-iodothyronamine (T(1)AM), an endogenous biogenic amine, is a potent agonist of the G protein-coupled trace amine-associated receptor 1 (TAAR1). T(1)AM is present in rat brain, and TAAR1 is expressed in hypothalamic nuclei associated with the regulation of energy homeostasis. AIM: The aim of this study was to determine the effects of T(1)AM on food intake in rodents. METHODS: We determined the effect of (i) intraperitoneal (i.p.) administration of T(1)AM on food intake, oxygen consumption (VO(2)) and locomotor activity in mice; (ii) intracerebroventricular (ICV) injection of T(1)AM on food intake in male rats; (iii) c-fos expression following ventricular administration of T(1)AM in male rats; and (iv) direct injection of T(1)AM into the arcuate nucleus (ARC) of male rats on food intake. RESULTS: (i) T(1)AM (4 nmol/kg) significantly increased food intake following i.p. injection in mice but had no effect on VO(2) or locomotor activity. (ii) ICV administration of T(1)AM (1.2 nmol/kg) significantly increased food intake in male rats. (iii) Intraventricular administration of T(1)AM significantly increased c-fos expression in the ARC of male rats. (iv) Direct administration of T(1)AM (0.12, 0.4 and 1.2 nmol/kg) into the ARC of male rats significantly increased food intake. CONCLUSION: These data suggest that T(1)AM is an orexigenic factor that may act through the ARC to increase food intake in rodents.
Assuntos
Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Aminas Biogênicas/administração & dosagem , Encéfalo/efeitos dos fármacos , Ingestão de Alimentos/efeitos dos fármacos , Tironinas/administração & dosagem , Animais , Núcleo Arqueado do Hipotálamo/metabolismo , Injeções Intraperitoneais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
Type V collagen (col[V])-reactive lymphocytes contribute to lung transplant rejection, but the mechanisms for emigration into the graft are unknown. Sphingosine-1-phosphate-1 receptors (S1P(1R)) are believed to be required for lymphocyte emigration in other studies, but their role in col(V)-reactive lymphocyte rejection responses is not known. Utilizing small interfering RNA (siRNA) to reduce S1P(1R) expression on col(V)-reactive lymphocytes, we examined the role of S1P(1R) in the rejection response. Quantitative polymerase chain reaction (PCR) revealed strong expression of S1P(1R) messenger RNA (mRNA)on col(V)-reactive lymphocytes isolated from immunized rats. S1P(1R)-specific siRNA (S1P(1R) siRNA) reduced expression of S1P(1R) mRNA and protein, whereas scramble siRNA (SC siRNA) had no effect. Adoptive transfer of lymphocytes treated with S1P(1R) siRNA to rat Wistar Kyoto (WKY) lung isograft recipients resulted in retention of cells within the liver with fewer cells in mediastinal lymph nodes when compared to cells exposed to SC siRNA. S1P(1R)-deficient cells proliferated in response to alloantigens, but not in response to col(V), and produced less interferon (IFN)-gamma in response to col(V) compared to controls. Downregulating S1P(1R) did not affect production of interleukin (IL)-10and tumor necrosis factor (TNF)-alpha, or expression of adhesion molecules critical for migration, but prevented rejection pathology and lowered local levels of IFN-gamma post adoptive transfer. These data demonstrate novel roles of S1P(1R,) which include regulating emigration and modulating lymphocyte activation.
Assuntos
Movimento Celular/genética , Colágeno Tipo V/imunologia , Rejeição de Enxerto/imunologia , Transplante de Pulmão , Receptores de Lisoesfingolipídeo/fisiologia , Linfócitos T/imunologia , Transferência Adotiva , Animais , Rejeição de Enxerto/patologia , Masculino , RNA Interferente Pequeno/farmacologia , Ratos , Ratos Endogâmicos WKY , Receptores de Lisoesfingolipídeo/antagonistas & inibidores , Receptores de Lisoesfingolipídeo/genética , Linfócitos T/efeitos dos fármacos , Linfócitos T/transplante , Transcrição Gênica/efeitos dos fármacosRESUMO
OBJECTIVE: The purpose of this study was to explore the multilevel contextual factors that influenced the implementation of the Obstetric Hemorrhage Initiative (OHI) among hospitals in Florida. STUDY DESIGN: A qualitative evaluation was conducted via in-depth interviews with multidisciplinary hospital staff (n=50) across 12 hospitals. Interviews were guided by the Consolidated Framework for Implementation Research and analyzed in Atlas.ti using rigorous qualitative analysis procedures. RESULT: Factors influencing OHI implementation were present across process (leadership engagement; engaging people; planning; reflecting), inner setting (for example, knowledge/beliefs; resources; communication; culture) and outer setting (for example, cosmopolitanism) levels. Moreover, factors interacted across levels and were not mutually exclusive. Leadership and staff buy-in emerged as important components influencing OHI implementation across disciplines. CONCLUSION: Key contextual factors found to influence OHI implementation experiences can be useful in informing future quality improvement interventions given the institutional and provider-level behavioral changes needed to account for evolving the best practices in perinatology.
Assuntos
Conhecimentos, Atitudes e Prática em Saúde , Comunicação Interdisciplinar , Hemorragia Pós-Parto/prevenção & controle , Hemorragia Pós-Parto/terapia , Melhoria de Qualidade/organização & administração , Feminino , Florida , Implementação de Plano de Saúde/organização & administração , Humanos , Entrevistas como Assunto , Perinatologia , Recursos Humanos em Hospital , Gravidez , Pesquisa QualitativaRESUMO
Kisspeptin-54 is the peptide product of the KiSS-1 gene and an endogenous agonist of the GPR54 receptor. KiSS-1 was initially discovered as a metastasis suppressor gene, but recent studies demonstrate that the kisspeptin/GPR54 system is a key regulator of the reproductive system. Disrupted GPR54 signalling causes hypogonadotrophic hypogonadism in rodents and man. Intracerebroventricular or peripheral administration of kisspeptin potently stimulates the hypothalamic-pituitary-gonadal (HPG) axis via the hypothalamic gonadotrophin-releasing hormone system. We have investigated the effect of injection of kisspeptin-54 into discrete hypothalamic regions on the HPG axis. To construct a dose-response curve for the effects of intrahypothalamic kisspeptin administration, adult male Wistar rats were cannulated into the medial preoptic area (MPOA) at the level of the organum vasculosum laminae terminalis (OVLT). Kisspeptin-54 was injected into the MPOA at doses of 0.01, 0.1, 1, 10 and 100 pmol. At 60 min following injection of 1, 10 or 100 pmol kisspeptin-54, plasma luteinising hormone (LH) and total testosterone levels were significantly increased. Adult male Wistar rats were then cannulated into the rostral preoptic area at the level of the OVLT (RPOA), the MPOA, the paraventricular (PVN), dorsomedial (DMN) and arcuate hypothalamic nuclei, and the lateral hypothalamic area. A dose of 1 pmol kisspeptin-54 was administered into all areas. The circulating levels of LH and total testosterone were significantly increased 60 min postinjection of kisspeptin-54 into the RPOA, MPOA, PVN and arcuate nucleus. Our results suggest that kisspeptin may mediate its effects on the HPG axis via these regions of the hypothalamus.
Assuntos
Hipotálamo/fisiologia , Hormônio Luteinizante/sangue , Testosterona/sangue , Proteínas Supressoras de Tumor/fisiologia , Análise de Variância , Animais , Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Núcleo Arqueado do Hipotálamo/fisiologia , Relação Dose-Resposta a Droga , Humanos , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Sistema Hipotálamo-Hipofisário/metabolismo , Hipotálamo/efeitos dos fármacos , Kisspeptinas , Masculino , Microinjeções , Núcleo Hipotalâmico Paraventricular/efeitos dos fármacos , Núcleo Hipotalâmico Paraventricular/fisiologia , Área Pré-Óptica/efeitos dos fármacos , Área Pré-Óptica/fisiologia , Ratos , Ratos Wistar , Testículo/efeitos dos fármacos , Testículo/metabolismo , Proteínas Supressoras de Tumor/administração & dosagemRESUMO
Galanin-like peptide (GALP) is a neuropeptide implicated in the regulation of feeding behaviour, metabolism and reproduction. GALP is an endogenous ligand of the galanin receptors, which are widely expressed in the hypothalamus. GALP is predominantly expressed in arcuate nucleus (ARC) neurones, which project to the paraventricular nucleus (PVN) and medial preoptic area (mPOA). Intracerebroventricular or intraparaventricular (iPVN) injection of GALP acutely increases food intake in rats. The effect of GALP injection into the mPOA on feeding behaviour has not previously been studied. In the present study, intra-mPOA (imPOA) injection of GALP potently increased 0-1-h food intake in rats. The dose-response effect of imPOA GALP administration on food intake was similar to that previously observed following iPVN administration. The effects of GALP (1 nmol) or galanin (1 nmol) on food intake were then compared following injection into the PVN, mPOA, ARC, dorsal medial nucleus (DMN), lateral hypothalamus and rostral preoptic area (rPOA). GALP (1 nmol) increased food intake to a similar degree when injected into the imPOA or iPVN, but produced no significant effect when injected into the ARC, DMN, lateral hypothalamus or rPOA. Similarly, galanin (1 nmol) significantly increased food intake following injection imPOA and iPVN. However, the effect was significantly smaller than that following administration of GALP (1 nmol). Galanin also had no significant effect on food intake when administered into the ARC, DMN, lateral hypothalamus and rPOA. These data suggest that the mPOA and the PVN may have specific roles in mediating the orexigenic effect of GALP and galanin.
Assuntos
Ingestão de Alimentos/efeitos dos fármacos , Peptídeo Semelhante a Galanina/farmacologia , Área Pré-Óptica/fisiologia , Animais , Mapeamento Encefálico , Relação Dose-Resposta a Droga , Galanina/administração & dosagem , Galanina/farmacologia , Peptídeo Semelhante a Galanina/administração & dosagem , Hipotálamo/anatomia & histologia , Hipotálamo/fisiologia , Masculino , Microinjeções , Ratos , Ratos Wistar , Estimulação Química , SuínosRESUMO
The effects of acute and repeated intraparaventricular (iPVN) administration of human relaxin-3 (H3) were examined on food intake, energy expenditure, and the hypothalamo-pituitary thyroid axis in male Wistar rats. An acute high dose iPVN injection of H3 significantly increased food intake 1 h post-administration [0.4+/-0.1 g (vehicle) vs 1.6+/-0.5 g (180 pmol H3), 2.4+/-0.5 g (540 pmol H3) and 2.2+/-0.5 g (1,620 pmol H3), p<0.05 for all doses vs vehicle]. Repeated iPVN H3 injection (180 pmol/twice a day for 7 days) significantly increased cumulative food intake in ad libitum fed animals compared with vehicle [211.8+/-7.1 g (vehicle) vs 261.6+/-6.7 g (ad libitum fed H3), p<0.05]. Plasma leptin was increased in the H3 ad libitum fed group. Plasma thyroid stimulating hormone was significantly decreased after acute and repeated administration of H3. These data suggest H3 may play a role in long-term control of food intake.
Assuntos
Metabolismo Energético , Relaxina/fisiologia , Doença Aguda , Tecido Adiposo/metabolismo , Animais , Peso Corporal , Humanos , Canais Iônicos/sangue , Leptina/sangue , Masculino , Proteínas Mitocondriais/sangue , Radioimunoensaio , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G/metabolismo , Relaxina/metabolismo , Tireotropina/sangue , Tireotropina/metabolismo , Proteína Desacopladora 1RESUMO
Exposure to prolonged environmental stress can have impacts on the cellular homeostasis of aquatic organisms. The current study employed two-dimensional electrophoresis (2-DE) to test whether exposure to impaired water quality conditions in the Sydney Harbour estuary has significantly altered the proteomes of the resident Sydney rock oyster (Saccostrea glomerata). Adult S. glomerata were sampled from four bays in the estuary. Each bay consisted of a "high-impact" site adjacent to point sources of chemical contamination (e.g., storm drains/canals or legacy hotspots) and a "low-impact" site located â¼5km away from point sources. A mixture of environmental stressors differed significantly between high- and low-impact sites. Specifically, PAHs, PCBs, tributyltin, Pb, and Zn were significantly elevated in oyster tissues from high-impact sites, together with depleted dissolved oxygen and low pH in the water column. A 2-DE proteomics analysis subsequently identified 238 protein spots across 24 2-DE gels, of which 27-50 spots differed significantly in relative intensity between high- and low-impact sites per bay. Twenty-five percent of the differential spots were identified in more than one bay. The identities of 80 protein spots were determined by mass spectrometry. HSP 70, PPIB, and radixin were the three most highly expressed differential proteins. Despite the largely unique proteomes evident in each bay, functional annotations revealed that half of the differentially expressed proteins fell into just two subcellular functional categories-energy metabolism and the cytoskeleton. These findings provide a framework to further investigate adaptation of cellular mechanisms to prolonged stress in S. glomerata.
Assuntos
Exposição Ambiental , Ostreidae/efeitos dos fármacos , Proteoma/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Animais , Estuários , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
Correction for 'The biology of environmental stress: molecular biomarkers in Sydney rock oysters (Saccostrea glomerata)' by D. A. Raftos et al., Environ. Sci.: Processes Impacts, 2016, 18, 1129-1139.
RESUMO
This review describes our recent work on environmental stress in Sydney rock oysters, focusing on the identification of molecular biomarkers for ecotoxicological analysis. We begin by describing the environmental pressures facing coastal estuaries in Australia, with particular reference to Sydney Harbour. After providing that context, we summarise our transcriptional and proteomic analyses of Sydney rock oysters responding to chemical contamination and other forms of environmental stress. This work has shown that the intracellular processes of oysters are highly responsive to environmental threats. Our data agree with the broader literature, which suggests that there is a highly conserved intracellular stress response in oysters involving a limited number of biological processes. We conclude that many effective molecular markers for environmental biomonitoring are likely to lie within these biological pathways.
Assuntos
Monitoramento Ambiental , Ostreidae/fisiologia , Estresse Fisiológico , Poluentes Químicos da Água/análise , Animais , Austrália , Biomarcadores/metabolismo , Estuários , Perfilação da Expressão Gênica , Ostreidae/metabolismo , ProteômicaRESUMO
Relaxin-3 (INSL-7) is a recently discovered member of the insulin superfamily. Relaxin-3 mRNA is expressed in the nucleus incertus of the brainstem, which has projections to the hypothalamus. Relaxin-3 binds with high affinity to the LGR7 receptor and to the previously orphan G protein-coupled receptor GPCR135. GPCR135 mRNA is expressed predominantly in the central nervous system, particularly in the paraventricular nucleus (PVN). The presence of relaxin-3 and these receptors in the PVN led us to investigate the effect of central administration of relaxin-3 on food intake in male Wistar rats. The receptor involved in mediating these effects was also investigated. Intracerebroventricular injections of human relaxin-3 (H3) to satiated rats significantly increased food intake 1 h post administration in the early light phase [0.96 +/- 0.16 g (vehicle) vs. 1.81 +/- 0.21 g (180 pmol H3), P < 0.05] and the early dark phase [2.95 +/- 0.45 g (vehicle) vs. 4.39 +/- 0.39 g (180 pmol H3), P < 0.05]. Intra-PVN H3 administration significantly increased 1-h food intake in satiated rats in the early light phase [0.34 +/- 0.16 g (vehicle) vs. 1.23 +/- 0.30 g (18 pmol H3), P < 0.05] and the early dark phase [4.43 +/- 0.32 g (vehicle) vs. 6.57 +/- 0.42 g (18 pmol H3), P < 0.05]. Feeding behavior increased after intra-PVN H3. Equimolar doses of human relaxin-2, which binds the LGR7 receptor but not GPCR135, did not increase feeding. Hypothalamic neuropeptide Y, proopiomelanocortin, or agouti-related peptide mRNA expression did not change after acute intracerebroventricular H3. These results suggest a novel role for relaxin-3 in appetite regulation.
Assuntos
Hiperfagia/induzido quimicamente , Núcleos da Linha Média do Tálamo/fisiologia , Relaxina/administração & dosagem , Relaxina/farmacologia , Animais , Ventrículos Cerebrais/efeitos dos fármacos , Ventrículos Cerebrais/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Hipotálamo/fisiopatologia , Injeções Intraventriculares , Masculino , Núcleos da Linha Média do Tálamo/efeitos dos fármacos , Neuropeptídeo Y/genética , Pró-Opiomelanocortina/genética , RNA Mensageiro/genética , Ratos , Ratos WistarRESUMO
Kisspeptin is the peptide product of the KiSS-1 gene and the endogenous agonist for the GPR54 receptor. Recent evidence suggests the kisspeptin/GPR54 system is a key regulator of the reproductive system. We examined the effect of intracerebroventricular (i.c.v.) and peripheral administration of the active kisspeptin fragment, kisspeptin-10, on circulating gonadotrophins and total testosterone levels in adult male rats. The effect of kisspeptin-10 in vitro on the release of hypothalamic peptides from hypothalamic explants and gonadotrophins from anterior pituitary fragments was also determined. The i.c.v. administration of kisspeptin-10 dose-dependently increased plasma luteinizing hormone (LH) and increased plasma follicle stimulating hormone (FSH) and total testosterone at 60 min postinjection. In a separate study investigating the time course of this response, i.c.v. administered kisspeptin-10 (3 nmol) significantly increased plasma LH at 10, 20 and 60 min, FSH at 60 min and total testosterone at 20 and 60 min postinjection. Kisspeptin-10 stimulated the release of luteinizing hormone-releasing hormone (LHRH) from in vitro hypothalamic explants. Peripheral administration of kisspeptin-10 increased plasma LH, FSH and total testosterone. However, doses of 100-1000 nM kisspeptin-10 did not influence LH or FSH release from pituitary fragments in vitro. Kisspeptin therefore potently stimulates the hypothalamic-pituitary-gonadal axis. These effects are likely to be mediated via the hypothalamic LHRH system.
Assuntos
Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Oligopeptídeos/farmacologia , Testículo/efeitos dos fármacos , Animais , Comportamento Animal/efeitos dos fármacos , Ritmo Circadiano/fisiologia , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Jejum/psicologia , Gonadotropinas/metabolismo , Injeções Intraventriculares , Kisspeptinas , Masculino , Oligopeptídeos/administração & dosagem , Adeno-Hipófise/metabolismo , Hormônios Hipofisários/sangue , Ratos , Ratos Wistar , Estimulação Química , Testosterona/metabolismoRESUMO
The potassium-activated hyperpolarization (KH) was used as an index of electrogenic Na+ pumping in bullfrog sympathetic ganglia. This response was evoked by storing ganglia in K-free Ringer's solution and briefly introducing normal Ringer's solution containing 2 mM K+ at regular intervals. The apparent EC50 for K+ was 2.21 mM (range 0.88-3.54 mM, for n = 5) and at least 10 mM K+ was required to produce a maximal KH response. Adrenaline, which produces membrane hyperpolarization by increasing K+ conductance (gK), increased the amplitude of KH responses. When the K+ efflux accompanying the adrenaline-induced hyperpolarization (AdH) was blocked with 2 mM Ba2+, the KH was no longer potentiated. It is suggested that the K+ moving out of the cells during the AdH accumulates extracellularly and stimulates the Na+ pump.
Assuntos
Epinefrina/fisiologia , Gânglios Simpáticos/fisiologia , Canais Iônicos/metabolismo , Potássio/fisiologia , Sódio/metabolismo , Animais , Bário/farmacologia , Técnicas In Vitro , Canais Iônicos/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Rana catesbeianaRESUMO
Kisspeptin plays a pivotal role in pubertal onset and reproductive function. In rodents, kisspeptin perikarya are located in 2 major populations: the anteroventral periventricular nucleus and the hypothalamic arcuate nucleus (ARC). These nuclei are believed to play functionally distinct roles in the control of reproduction. The anteroventral periventricular nucleus population is thought to be critical in the generation of the LH surge. However, the physiological role played by the ARC kisspeptin neurons remains to be fully elucidated. We used bilateral stereotactic injection of recombinant adeno-associated virus encoding kisspeptin antisense into the ARC of adult female rats to investigate the physiological role of kisspeptin neurons in this nucleus. Female rats with kisspeptin knockdown in the ARC displayed a significantly reduced number of both regular and complete oestrous cycles and significantly longer cycles over the 100-day period of the study. Further, kisspeptin knockdown in the ARC resulted in a decrease in LH pulse frequency. These data suggest that maintenance of ARC-kisspeptin levels is essential for normal pulsatile LH release and oestrous cyclicity.
Assuntos
Núcleo Arqueado do Hipotálamo/citologia , Regulação da Expressão Gênica , Kisspeptinas/fisiologia , Neurônios/metabolismo , Reprodução/fisiologia , Animais , Estradiol/metabolismo , Ciclo Estral , Retroalimentação Fisiológica , Feminino , Proteínas de Fluorescência Verde/metabolismo , Imunoensaio , Kisspeptinas/genética , Hormônio Luteinizante/metabolismo , Oligonucleotídeos Antissenso/genética , Ratos , Ratos Wistar , Proteínas Recombinantes/genética , Fatores de TempoRESUMO
Neuromedin B (NMB) is a highly conserved bombesin-related peptide found in mammals. NMB mRNA is detected in the central nervous system (CNS) and is highly expressed in the rat hypothalamus, in particular the medial preoptic area and the arcuate nucleus. The mammalian bombesin family of receptors consists of three closely related G protein coupled receptors, BB1, BB2 and BB3. The BB1 receptor subtype has the highest affinity for NMB. NMB has well documented roles in the regulation of the thyroid axis and the stress axis in rats. However, there is little available data regarding the role of NMB in the regulation of the hypothalamic-pituitary-gonadal (HPG) axis. It is known that the NMB receptor is expressed in immortalised gonadotrophin releasing hormone (GnRH) releasing GT1-7 cells and murine forebrain GnRH neurons, and that anterior pituitary NMB-immunoreactivity is altered by changes in the sex steroid environment. The objective of these studies was thus to further investigate the effects of NMB on the HPG axis. Intracerebroventricular (ICV) administration of NMB (10 nmol) to adult male rats significantly increased plasma luteinising hormone (LH) levels 30 min after injection (plasma LH ng/ml; saline 0.69±0.07, 10 nmol NMB 1.33±0.17, P<0.01). In vitro, NMB stimulated GnRH release from hypothalamic explants from male rats and from hypothalamic GT1-7 cells. NMB had no significant effect on LH release from anterior pituitary explants from male rats, or from pituitary LßT2 cells in vitro. These results suggest a previously unreported role for NMB in the stimulation of the HPG axis via hypothalamic GnRH. Further work is now required to determine the receptor mediating the effects of NMB on the reproductive axis and the physiological role of NMB in reproduction.
Assuntos
Sistema Hipotálamo-Hipofisário , Neurocinina B/análogos & derivados , Sistema Hipófise-Suprarrenal , Animais , Linhagem Celular , Hormônio Liberador de Gonadotropina/metabolismo , Gonadotropinas/sangue , Humanos , Hipotálamo/metabolismo , Hormônio Luteinizante/metabolismo , Masculino , Neurocinina B/fisiologia , Hipófise/metabolismo , Ratos , Ratos Wistar , Testosterona/sangue , Técnicas de Cultura de TecidosRESUMO
Nerve growth factor (NGF) can augment transmitter release in sensory neurons by acutely sensitizing sensory neurons and by increasing the expression of calcitonin gene-related peptide (CGRP) over time. The current study examined the intracellular signaling pathways that mediate these two temporally distinct effects of NGF to augment CGRP release from sensory neurons. Growing sensory neurons in 30 or 100 ng/mL of NGF for 7 days increases CGRP content and this increase augments the amount of CGRP that is released by high extracellular potassium. Overexpressing a dominant negative Ras, Ras(17N) or treatment with a farnesyltransferase inhibitor attenuates the NGF-induced increase in CGRP content. Conversely, overexpressing a constitutively active Ras augments the NGF-induced increase in content of CGRP. Inhibiting mitogen activated protein kinase (MEK) activity also blocks the ability of NGF to increase CGRP expression. In contrast to the ability of chronic NGF to increase peptide content, acute exposure of sensory neurons to 100 ng/mL NGF augments capsaicin-evoked release of CGRP without affecting the content of CGRP. This sensitizing action of NGF is not affected by inhibiting Ras, MEK, or PI3 kinases. In contrast, the NGF-induced increase in capsaicin-evoked release of CGRP is blocked by the protein kinase C (PKC) inhibitor, BIM and the Src family kinases inhibitor, PP2. These data demonstrate that different signaling pathways mediate the alterations in expression of CGRP by chronic NGF and the acute actions of the neurotrophin to augment capsaicin-evoked release of CGRP in the absence of a change in the content of the peptide.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina/genética , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Fator de Crescimento Neural/fisiologia , Nociceptores/metabolismo , Células Receptoras Sensoriais/metabolismo , Transdução de Sinais/fisiologia , Regulação para Cima/fisiologia , Animais , Peptídeo Relacionado com Gene de Calcitonina/biossíntese , Células Cultivadas , Gânglios Espinais/metabolismo , Gânglios Espinais/fisiologia , Masculino , Fator de Crescimento Neural/metabolismo , Nociceptores/fisiologia , Radioimunoensaio , Ratos , Ratos Sprague-Dawley , Células Receptoras Sensoriais/fisiologia , Transdução de Sinais/genética , Regulação para Cima/genéticaRESUMO
Growing evidence suggests the tachykinin neurokinin B (NKB) may modulate gonadotrophin secretion and play a role in sex-steroid feedback within the reproductive axis. NKB signalling has recently been identified as being necessary for normal human reproductive function, although the precise mechanisms underpinning this role remain to be established. We have used rodents to explore further the role of NKB within the reproductive axis. In particular, we have studied its interactions with kisspeptin, a neuropeptide essential for reproductive function in rodent and human with close anatomical links to NKB within the hypothalamus. Intraperitoneal administration of NKB (50 nmol) to male mice had no effect on circulating luteinsing hormone (LH) levels and, although i.p. kisspeptin (15 nmol) increased LH five-fold, co-administration of NKB and kisspeptin was indistinguishable from kisspeptin alone. Intracerebroventricular administration of NKB (10 nmol) to male mice also had no effect on LH levels, with 1 nmol kisspeptin i.c.v. significantly increasing LH compared to control (0.37 +/- 0.18 versus 5.11 +/- 0.28 ng/ml, respectively). Interestingly, i.c.v. co-administration of NKB and kisspeptin caused a significant increase in LH concentrations compared to kisspeptin alone (8.96 +/- 1.82 versus 5.11 +/- 0.28 ng/ml respectively). We used hypothalamic explants from rats to assess the effect of NKB on gonadotrpohin-releasing hormone (GnRH) secretion ex vivo. Doses of NKB up to 1000 nm failed to stimulate GnRH secretion, whereas 100 nm kisspeptin robustly increased GnRH secretion. Of note, co-administration of NKB with kisspeptin abrogated the effect of kisspeptin, producing no GnRH release above basal state. Finally, we analysed the expression of Tac2/Tacr3 (genes encoding NKB and NK3R, respectively) within the arcuate nucleus in different nutritional states. After a 48-h fast, the expression of both Tac2 and Tacr3 showed a significant increase, in contrast to levels of Kiss1 and Kiss1r mRNA, which remained unchanged. In male rodent models, NKB and kisspeptin have different effects upon gonadotrophin release and appear to interact in a complex manner.