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Chem Commun (Camb) ; 51(27): 6018-21, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25744824
Adv Exp Med Biol ; 846: 139-62, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25472537


The output of prolactin (PRL) is highly dynamic with dramatic changes in its secretion from the anterior pituitary gland depending on prevailing physiological status. In adult female mice, there are three distinct phases of output and each of these is related to the functions of PRL at specific stages of reproduction. Recent studies of the changes in the regulation of PRL during its period of maximum output, lactation, have shown alterations at both the level of the anterior pituitary and hypothalamus. The PRL-secreting cells of the anterior pituitary are organised into a homotypic network in virgin animals, facilitating coordinated bouts of activity between interconnected PRL cells. During lactation, coordinated activity increases due to the changes in structural connectivity, and this drives large elevations in PRL secretion. Surprisingly, these changes in connectivity are maintained after weaning, despite reversion of PRL output to that of virgin animals, and result in an augmented output of hormone during a second lactation. At the level of the hypothalamus, tuberoinfundibular dopamine (TIDA) neurons, the major inhibitors of PRL secretion, have unexpectedly been shown to remain responsive to PRL during lactation. However, there is an uncoupling between TIDA neuron firing and dopamine secretion, with a potential switch to enkephalin release. Such a process may reinforce hormone secretion through dual disinhibition and stimulation of PRL cell activity. Thus, integration of signalling along the hypothalamo-pituitary axis is responsible for increased secretory output of PRL cells during lactation, as well as allowing the system to anticipate future demands.

Lactotrofos/metabolismo , Prolactina/metabolismo , Adulto , Animais , Feminino , Crescimento e Desenvolvimento/fisiologia , Humanos , Lactação/fisiologia , Camundongos , Plasticidade Neuronal/fisiologia , Gravidez , Reprodução/fisiologia , Transdução de Sinais/genética
Chem Sci ; 5(9): 3528-3535, 2014 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-25580213


We describe a one-pot strategy for the high yielding, operationally simple synthesis of fluorescent probes for Zn2+ that bear biological targeting groups and exemplify the utility of our method through the preparation of a small library of sensors. Investigation of the fluorescence behaviour of our library revealed that although all behaved as expected in MeCN, under biologically relevant conditions in HEPES buffer, a plasma membrane targeting sensor displayed a dramatic switch on response to excess Zn2+ as a result of aggregation phenomena. Excitingly, in cellulo studies in mouse pancreatic islets demonstrated that this readily available sensor was indeed localised to the exterior of the plasma membrane and clearly responded to the Zn2+ co-released when the pancreatic beta cells were stimulated to release insulin. Conversely, sensors that target intracellular compartments were unaffected. These results demonstrate that this sensor has the potential to allow the real time study of insulin release from living cells and exemplifies the utility of our simple synthetic approach.

Front Neuroendocrinol ; 33(3): 252-66, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22981652


Both endocrine and non-endocrine cells of the pituitary gland are organized into structural and functional networks which are formed during embryonic development but which may be modified throughout life. Structural mapping of the various endocrine cell types has highlighted the existence of distinct network motifs and relationships with the vasculature which may relate to temporal differences in their output. Functional characterization of the network activity of growth hormone and prolactin cells has revealed a role for cell organization in gene regulation, the plasticity of pituitary hormone output and remarkably the ability to memorize altered demand. As such, the description of these endocrine cell networks alters the concept of the pituitary from a gland which simply responds to external regulation to that of an oscillator which may memorize information and constantly adapt its coordinated networks' responses to the flow of hypothalamic inputs.

Adeno-Hipófise/citologia , Animais , Comunicação Celular/fisiologia , Diferenciação Celular , Corticotrofos/fisiologia , Células Endócrinas/fisiologia , Feminino , Gonadotrofos/fisiologia , Hormônio do Crescimento/metabolismo , Masculino , Camundongos , Modelos Biológicos , Adeno-Hipófise/irrigação sanguínea , Adeno-Hipófise/embriologia , Somatotrofos/fisiologia , Células-Tronco/fisiologia
J Neuroendocrinol ; 22(12): 1217-25, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20673299


Endocrine cells in the mammalian pituitary are arranged into three-dimensional homotypic networks that wire the gland and act to optimise hormone output by allowing the transmission of information between cell ensembles in a temporally precise manner. Despite this, the structure-function relationships that allow cells belonging to these networks to display coordinated activity remain relatively uncharacterised. This review discusses the recent technological advances that have allowed endocrine cell network structure and function to be probed and the mathematical models that can be used to analyse and present the resulting data. In particular, we focus on the mechanisms that allow endocrine cells to dynamically function as a population to drive hormone release as well as the experimental and theoretical methods that are used to track and model information flow through the network.

Modelos Teóricos , Hipófise/fisiologia , Animais , Humanos , Neurônios/fisiologia , Hipófise/citologia
J Neuroendocrinol ; 22(6): 509-17, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20236228


A combined suppressive effect of prolactin (PRL) and dopamine on the secretion of luteinising hormone (LH) at the level of the pituitary gland has been identified in sheep, a short-day breeder. However, little is known about the role of PRL in the intra-pituitary regulation of the gonadotrophic axis in long-day breeders. In the present study, we investigated the effects of PRL on LH and follicle-stimulating hormone (FSH) secretion during the equine annual reproductive cycle. Horse pituitaries were obtained during the breeding season (BS) and nonbreeding season (NBS). Cells were dispersed, plated to monolayer cultures and assigned to one of the following specific treatments: (i) medium (Control); (ii) rat PRL (rPRL); (iii) thyrotrophin-releasing hormone (TRH); (iv) bromocriptine (Br); and (v) Br + rPRL. Gonadotrophin-releasing hormone (GnRH) dose-dependently stimulated LH release during the BS and NBS. During the BS, neither rPRL nor TRH affected the LH response to GnRH, but Br significantly (P < 0.01) enhanced both basal and GnRH-stimulated LH release through a mechanism that did not involve alterations in the concentrations of PRL. However, rPRL prevented the Br-induced increase in basal and GnRH-stimulated LH output, and suppressed LH below basal values (P < 0.05). Conversely, during the NBS, no significant effects of treatments were observed. Interestingly, at this time of year, the incidence of pituitary gap junctions within the pars distalis decreased by 50% (P < 0.01). By contrast to the effects on LH, no treatment effects were detected on the FSH response to GnRH, which was only apparent during the NBS. These results reveal no direct effects of PRL but an interaction between PRL and dopamine in the inhibitory regulation of LH, but not FSH, release at the level of the pituitary in the horse, and a modulatory role of season/photoperiod associated with alterations in folliculostellate cell-derived gap junctions.

Hormônio Foliculoestimulante/metabolismo , Hormônio Liberador de Gonadotropina/fisiologia , Hormônio Luteinizante/metabolismo , Prolactina/fisiologia , Reprodução/fisiologia , Animais , Feminino , Junções Comunicantes/metabolismo , Cavalos , Imuno-Histoquímica , Estações do Ano
Clin Oncol (R Coll Radiol) ; 17(3): 185-91, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15901003


AIMS: Current treatment for primary central nervous system lymphoma (PCNSL) involves high-dose methotrexate (HDMTX) with or without radiotherapy. Many published studies describing this approach include a highly selected group of patients. We report a single-centre experience of unselected cases of PCNSL. MATERIALS AND METHODS: We retrospectively reviewed the case notes of 55 consecutive patients diagnosed with biopsy-proven PCNSL between 1995 and 2003 at Addenbrooke's Hospital Cambridge, UK. We describe the treatment and outcome, including survival, treatment-related toxicity and long-term functional disability. RESULTS: At diagnosis, 45% of patients were considered unfit to receive treatment with HDMTX, owing to poor performance status or comorbidity. These patients had a median survival of 46 days and may not have been included in other published studies. The remaining patients were treated with a chemotherapy regimen, which included HDMTX. Patients who received at least one cycle of a chemotherapy containing HDMTX had a median survival of 31 months. Forty per cent did not complete planned chemotherapy owing to toxicity, disease progression or death. The median survival of patients treated with HDMTX aged 60 years compared with patients aged under 60 years was 26 months vs 41 months (P = 0.07), respectively. Younger patients treated with HDMTX, who achieved complete remission with chemotherapy, had a median survival of 56 months. We identified a high incidence of functional disability among survivors, resulting from a combination of the tumour itself, the neurosurgical procedure required for diagnosis and the late neurotoxicity of combined chemoradiotherapy. CONCLUSION: The treatment of PCNSL is associated with significant early and late toxicity. Further attempts to improve treatment should address mechanisms to reduce this toxicity. In particular, the benefit of radiotherapy in patients who achieve complete remission with HDMTX will remain uncertain until it is addressed in a multicentre, randomised trial.

Antimetabólitos Antineoplásicos/administração & dosagem , Neoplasias do Sistema Nervoso Central/tratamento farmacológico , Linfoma/tratamento farmacológico , Metotrexato/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias do Sistema Nervoso Central/mortalidade , Neoplasias do Sistema Nervoso Central/radioterapia , Feminino , Humanos , Linfoma/mortalidade , Linfoma/radioterapia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Análise de Sobrevida , Resultado do Tratamento