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1.
iScience ; 23(3): 100921, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32143135

RESUMO

Based on the type-I cannabinoid receptor (CB1) content of hypophysiotropic axons and the involvement of tanycytes in the regulation of the hypothalamic-pituitary-thyroid (HPT) axis, we hypothesized that endocannabinoids are involved in the tanycyte-induced regulation of TRH release in the median eminence (ME). We demonstrated that CB1-immunoreactive TRH axons were associated to DAGLα-immunoreactive tanycyte processes in the external zone of ME and showed that endocannabinoids tonically inhibit the TRH release in this tissue. We showed that glutamate depolarizes the tanycytes, increases their intracellular Ca2+ level and the 2-AG level of the ME via AMPA and kainite receptors and glutamate transport. Using optogenetics, we demonstrated that glutamate released from TRH neurons influences the tanycytes in the ME. In summary, tanycytes regulate TRH secretion in the ME via endocannabinoid release, whereas TRH axons regulate tanycytes by glutamate, suggesting the existence of a reciprocal microcircuit between tanycytes and TRH terminals that controls TRH release.

2.
J Comp Neurol ; 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31950494

RESUMO

The hypothalamus contains catecholaminergic neurons marked by the expression of tyrosine hydroxylase (TH). As multiple chemical messengers coexist in each neuron, we determined if hypothalamic TH-immunoreactive (ir) neurons express vesicular glutamate or GABA transporters. We used Cre/loxP recombination to express enhanced GFP (EGFP) in neurons expressing the vesicular glutamate (vGLUT2) or GABA transporter (vGAT), then determined whether TH-ir neurons colocalized with native EGFPVglut2 - or EGFPVgat -fluorescence, respectively. EGFPVglut2 neurons were not TH-ir. However, discrete TH-ir signals colocalized with EGFPVgat neurons, which we validated by in situ hybridization for Vgat mRNA. To contextualize the observed pattern of colocalization between TH-ir and EGFPVgat , we first performed Nissl-based parcellation and plane-of-section analysis, and then mapped the distribution of TH-ir EGFPVgat neurons onto atlas templates from the Allen Reference Atlas (ARA) for the mouse brain. TH-ir EGFPVgat neurons were distributed throughout the rostrocaudal extent of the hypothalamus. Within the ARA ontology of gray matter regions, TH-ir neurons localized primarily to the periventricular hypothalamic zone, periventricular hypothalamic region, and lateral hypothalamic zone. There was a strong presence of EGFPVgat fluorescence in TH-ir neurons across all brain regions, but the most striking colocalization was found in a circumscribed portion of the zona incerta (ZI)-a region assigned to the hypothalamus in the ARA-where every TH-ir neuron expressed EGFPVgat . Neurochemical characterization of these ZI neurons revealed that they display immunoreactivity for dopamine but not dopamine ß-hydroxylase. Collectively, these findings indicate the existence of a novel mouse hypothalamic population that may signal through the release of GABA and/or dopamine.

3.
Thyroid ; 29(12): 1858-1868, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31659941

RESUMO

Background: Glycine is a classical neurotransmitter that has role in both inhibitory and excitatory synapses. To understand whether glycinergic inputs are involved in the regulation of the hypophysiotropic thyrotropin-releasing hormone (TRH) neurons, the central controllers of the hypothalamic-pituitary-thyroid axis, the glycinergic innervation of the TRH neurons was studied in the hypothalamic paraventricular nucleus (PVN). Methods: Double-labeling immunocytochemistry and patch-clamp electrophysiology were used to determine the role of glycinergic neurons in the regulation of TRH neurons in the PVN. Anterograde and retrograde tracing methods were used to determine the sources of the glycinergic input of TRH neurons. Results: Glycine transporter-2 (GLYT2), a marker of glycinergic neurons, containing axons were found to establish symmetric type of synapses on TRH neurons in the PVN. Furthermore, glycine receptor immunoreactivity was observed in these TRH neurons. The raphe magnus (RMg) and the ventrolateral periaqueductal gray (VLPAG) were found to be the exclusive sources of the glycinergic innervation of the TRH neurons within the PVN. Patch-clamp electrophysiology using sections of TRH-IRES-tdTomato mice showed that glycine hyperpolarized the TRH neurons and completely blocked the firing of these neurons. Glycine also markedly hyperpolarized the TRH neurons in the presence of tetrodotoxin demonstrating the direct effect of glycine. In more than 60% of the TRH neurons, spontaneous inhibitory postsynaptic currents (sIPSCs) were observed, even after the pharmacological inhibition of glutamatergic and GABAergic neuronal transmission. The glycine antagonist, strychnine, almost completely abolished these sIPSCs, demonstrating the inhibitory nature of the glycinergic input of TRH neurons. Conclusions: These data demonstrate that TRH neurons in the PVN receive glycinergic inputs from the RMg and the VLPAG. The symmetric type of synaptic connection and the results of the electrophysiological experiments demonstrate the inhibitory nature of these inputs.

4.
JAMA Netw Open ; 2(8): e198898, 2019 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-31397861

RESUMO

Importance: Large studies investigating long-term outcomes of patients with bilateral pheochromocytomas treated with either total or cortical-sparing adrenalectomies are needed to inform clinical management. Objective: To determine the association of total vs cortical-sparing adrenalectomy with pheochromocytoma-specific mortality, the burden of primary adrenal insufficiency after bilateral adrenalectomy, and the risk of pheochromocytoma recurrence. Design, Setting, and Participants: This cohort study used data from a multicenter consortium-based registry for 625 patients treated for bilateral pheochromocytomas between 1950 and 2018. Data were analyzed from September 1, 2018, to June 1, 2019. Exposures: Total or cortical-sparing adrenalectomy. Main Outcomes and Measures: Primary adrenal insufficiency, recurrent pheochromocytoma, and mortality. Results: Of 625 patients (300 [48%] female) with a median (interquartile range [IQR]) age of 30 (22-40) years at diagnosis, 401 (64%) were diagnosed with synchronous bilateral pheochromocytomas and 224 (36%) were diagnosed with metachronous pheochromocytomas (median [IQR] interval to second adrenalectomy, 6 [1-13] years). In 505 of 526 tested patients (96%), germline mutations were detected in the genes RET (282 patients [54%]), VHL (184 patients [35%]), and other genes (39 patients [7%]). Of 849 adrenalectomies performed in 625 patients, 324 (52%) were planned as cortical sparing and were successful in 248 of 324 patients (76.5%). Primary adrenal insufficiency occurred in all patients treated with total adrenalectomy but only in 23.5% of patients treated with attempted cortical-sparing adrenalectomy. A third of patients with adrenal insufficiency developed complications, such as adrenal crisis or iatrogenic Cushing syndrome. Of 377 patients who became steroid dependent, 67 (18%) developed at least 1 adrenal crisis and 50 (13%) developed iatrogenic Cushing syndrome during median (IQR) follow-up of 8 (3-25) years. Two patients developed recurrent pheochromocytoma in the adrenal bed despite total adrenalectomy. In contrast, 33 patients (13%) treated with successful cortical-sparing adrenalectomy developed another pheochromocytoma within the remnant adrenal after a median (IQR) of 8 (4-13) years, all of which were successfully treated with another surgery. Cortical-sparing surgery was not associated with survival. Overall survival was associated with comorbidities unrelated to pheochromocytoma: of 63 patients who died, only 3 (5%) died of metastatic pheochromocytoma. Conclusions and Relevance: Patients undergoing cortical-sparing adrenalectomy did not demonstrate decreased survival, despite development of recurrent pheochromocytoma in 13%. Cortical-sparing adrenalectomy should be considered in all patients with hereditary pheochromocytoma.

5.
Int J Mol Sci ; 20(11)2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31185588

RESUMO

A syndrome of multiple paragangliomas/pheochromocytomas, somatostatinoma, and polycythemia due to somatic mosaic gain-of-function mutation of EPAS1, encoding HIF-2α, was previously described. HIF-2α has been implicated in endochondral and intramembranous ossification. Abnormal bone growth of the skull base may lead to Chiari malformation type I. We report two cases of EPAS1 gain-of-function mutation syndrome with Chiari malformation and developmental skull base anomalies. Patients were referred to the Section on Medical Endocrinology, Eunice Kennedy Shriver NICHD, NIH for evaluation of recurrent and metastatic paragangliomas or pheochromocytoma. The syndrome was confirmed genetically by identification of the functional EPAS1 gain-of-function mutation in the resected tumors and circulating leukocytes. Both patients were confirmed for characteristics of EPAS1 gain-of-function mutation syndrome by complete blood count (CBC), plasma biochemistry, and computed tomography (CT) of the abdomen and pelvis. Chiari malformation type I and abnormal bony development of the posterior fossa was found on MRI and CT of the head. The present study implicates EPAS1 mutations in abnormal posterior fossa development resulting in Chiari malformation type I.


Assuntos
Malformação de Arnold-Chiari/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Anormalidades Craniofaciais/genética , Paraganglioma/genética , Adulto , Malformação de Arnold-Chiari/diagnóstico por imagem , Malformação de Arnold-Chiari/patologia , Anormalidades Craniofaciais/diagnóstico por imagem , Anormalidades Craniofaciais/patologia , Feminino , Mutação com Ganho de Função , Humanos , Masculino , Pessoa de Meia-Idade , Paraganglioma/diagnóstico por imagem , Paraganglioma/patologia , Síndrome
6.
eNeuro ; 6(2)2019.
Artigo em Inglês | MEDLINE | ID: mdl-30957016

RESUMO

Hypothalamic POMC deficiency leads to obesity and metabolic deficiencies, largely due to the loss of melanocortin peptides. However, POMC neurons in the arcuate nucleus (ARC) are comprised of glutamatergic and GABAergic subpopulations. The developmental program, relative proportion and function of these two subpopulations are unresolved. To test whether glutamatergic POMC neurons serve a distinct role in maintaining energy homeostasis, we activated Pomc expression Cre- dependently in Vglut2-expressing neurons of mice with conditionally silenced Pomc alleles. The Vglut2-Pomc restored mice had normal ARC Pomc mRNA levels, POMC immunoreactivity, as well as body weight and body composition at age 12 weeks. Unexpectedly, the cumulative total of Vglut2+ glutamatergic- and Gad67+ GABAergic-Pomc neurons detected by in situ hybridization (ISH) exceeded 100% in both Vglut2- Pomc restored and control mice, indicating that a subpopulation of Pomc neurons must express both neuronal markers. Consistent with this hypothesis, triple ISH of C57BL/6J hypothalami revealed that 35% of ARC Pomc neurons were selectively Gad67 +, 21% were selectively Vglut2 +, and 38% expressed both Gad67 and Vglut2. The single Gad67 + and Vglut2 + Pomc neurons were most prevalent in the rostral ARC, while the Vglut2/Gad67 + dual-phenotype cells predominated in the caudal ARC. A lineage trace using Ai9-tdTomato reporter mice to label fluorescently all Vglut2-expressing neurons showed equal numbers of tdTomato+ and tdTomato- POMC immunoreactive neurons. Together, these data suggest that POMC neurons exhibit developmental plasticity in their expression of glutamatergic and GABAergic markers, enabling re-establishment of normal energy homeostasis in the Vglut2-Pomc restored mice.

7.
J Comp Neurol ; 527(6): 1070-1101, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30370602

RESUMO

Thyrotropin-releasing hormone (TRH) regulates the hypothalamic-pituitary-thyroid axis in mammals and also regulates prolactin secretion, directly or indirectly via tuberoinfundibular dopamine neurons. Although TRH is abundantly expressed in teleost brain and believed to mediate neuronal communication, empirical evidence is lacking. We analyzed pro-TRH-mRNA expression, mapped TRH-immunoreactive elements in the brain and pituitary, and explored its role in regulation of hypophysiotropic dopamine (DA) neurons in the catfish, Clarias batrachus. Partial pro-TRH transcript from C. batrachus transcriptome showed six TRH progenitors repeats. Quantitative real-time polymerase chain reaction (qRT-PCR) identified pro-TRH transcript in a number of different brain regions and immunofluorescence showed TRH-immunoreactive cells/fibers in the olfactory bulb, telencephalon, preoptic area (POA), hypothalamus, midbrain, hindbrain, and spinal cord. In the pituitary, TRH-immunoreactive fibers were seen in the neurohypophysis, proximal pars distalis, and pars intermedia but not rostral pars distalis. In POA, distinct TRH-immunoreactive cells/fibers were seen in nucleus preopticus periventricularis anterior (NPPa) that demonstrated a significant increase in TRH-immunoreactivity when collected during preparatory and prespawning phases, reaching a peak in the spawning phase. Although tyrosine hydroxylase (TH)-immunoreactive neurons in NPPa are hypophysiotropic, none of the TRH-immunoreactive neurons in NPPa accumulated neuronal tracer DiI following implants into the pituitary. However, 87 ± 1.6% NPPa TH-immunoreactive neurons were surrounded by TRH-immunoreactive axons that were seen in close proximity to the somata. Superfused POA slices treated with TRH (0.5-2 µM) significantly reduced TH concentration in tissue homogenates and the percent TH-immunoreactive area in the NPPa. We suggest that TRH in the brain of C. batrachus regulates a range of physiological functions but in particular, serves as a potential regulator of hypophysiotropic DA neurons and reproduction.

8.
Mol Metab ; 18: 120-133, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30274714

RESUMO

OBJECTIVE: Neuropeptide Y (NPY) is one of the most potent orexigenic peptides. The hypothalamic paraventricular nucleus (PVN) is a major locus where NPY exerts its effects on energy homeostasis. We investigated how NPY exerts its effect within the PVN. METHODS: Patch clamp electrophysiology and Ca2+ imaging were used to understand the involvement of Ca2+ signaling and retrograde transmitter systems in the mediation of NPY induced effects in the PVN. Immuno-electron microscopy were performed to elucidate the subcellular localization of the elements of nitric oxide (NO) system in the parvocellular PVN. In vivo metabolic profiling was performed to understand the role of the endocannabinoid and NO systems of the PVN in the mediation of NPY induced changes of energy homeostasis. RESULTS: We demonstrated that NPY inhibits synaptic inputs of parvocellular neurons in the PVN by activating endocannabinoid and NO retrograde transmitter systems via mobilization of Ca2+ from the endoplasmic reticulum, suggesting that NPY gates the synaptic inputs of parvocellular neurons in the PVN to prevent the influence of non-feeding-related inputs. While intraPVN administered NPY regulates food intake and locomotor activity via NO signaling, the endocannabinoid system of the PVN selectively mediates NPY-induced decrease in energy expenditure. CONCLUSION: Thus, within the PVN, NPY stimulates the release of endocannabinoids and NO via Ca2+-influx from the endoplasmic reticulum. Both transmitter systems appear to have unique roles in the mediation of the NPY-induced regulation of energy homeostasis, suggesting that NPY regulates food intake, energy expenditure, and locomotor activity through different neuronal networks of this nucleus.


Assuntos
Endocanabinoides/metabolismo , Metabolismo Energético , Neuropeptídeo Y/metabolismo , Óxido Nítrico/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Animais , Sinalização do Cálcio , Masculino , Camundongos , Núcleo Hipotalâmico Paraventricular/fisiologia , Potenciais Sinápticos
9.
J Comp Neurol ; 526(15): 2444-2461, 2018 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-30242838

RESUMO

We recently reported that the number of hypothalamic tanycytes expressing pro-opiomelanocortin (Pomc) is highly variable among brains of adult rats. While its cause and significance remain unknown, identifying other variably expressed genes in tanycytes may help understand this curious phenomenon. In this in situ hybridization study, we report that the Prss56 gene, which encodes a trypsin-like serine protease and is expressed in neural stem/progenitor cells, shows a similarly variable mRNA expression in tanycytes of adult rats and correlates inversely with tanycyte Pomc mRNA. Prss56 was expressed in α1, ß1, subsets of α2, and some median eminence γ tanycytes, but virtually absent from ß2 tanycytes. Prss56 was also expressed in vimentin positive tanycyte-like cells in the parenchyma of the ventromedial and arcuate nuclei, and in thyrotropin beta subunit-expressing cells of the pars tuberalis of the pituitary. In contrast to adults, Prss56 expression was uniformly high in tanycytes in adolescent rats. In mice, Prss56-expressing tanycytes and parenchymal cells were also observed but fewer in number and without significant variations. The results identify Prss56 as a second gene that is expressed variably in tanycytes of adult rats. We propose that the variable, inversely correlating expression of Prss56 and Pomc reflect periodically oscillating gene expression in tanycytes rather than stable expression levels that vary between individual rats. A possible functional link between Prss56 and POMC, and Prss56 as a potential marker for migrating tanycytes are discussed.


Assuntos
Células Ependimogliais/metabolismo , Hipotálamo/metabolismo , Pró-Opiomelanocortina/biossíntese , Pró-Opiomelanocortina/genética , Serina Proteases/biossíntese , Serina Proteases/genética , Envelhecimento/metabolismo , Animais , Contagem de Células , Células Ependimogliais/classificação , Feminino , Regulação da Expressão Gênica , Hipotálamo/química , Antígeno Ki-67/metabolismo , Masculino , Hipófise/metabolismo , Ratos , Ratos Sprague-Dawley , Serina Proteases/metabolismo , Terminologia como Assunto , Tireotropina/biossíntese , Tireotropina/genética
10.
Neurosurg Focus ; 44(6): E9, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29852762

RESUMO

A 71-year-old female patient was referred in 2013 for evaluation of an asymptomatic nonsecreting pituitary adenoma. The adenoma, measuring 13 mm in height by 10 mm in width, was discovered incidentally on imaging in 2012. Biochemical testing demonstrated a nonfunctioning adenoma. Given the relatively small lesion size and the lack of symptoms, observation was preferred over surgical intervention. The patient was monitored with routine MRI, which until 2016 demonstrated minimal growth. In early 2016, the patient developed recurrence of metastatic breast cancer and was treated with palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor. This inhibitor acts on a pathway believed to be involved in pituitary adenoma tumorigenesis. One year after starting palbociclib, routine imaging demonstrated significant regression of her pituitary adenoma. The authors hypothesize that inhibition of the CDK4/6 pathway by palbociclib contributed to adenoma regression in this patient, and that palbociclib may represent a possible adjuvant therapy for the treatment of nonfunctioning pituitary adenomas.


Assuntos
Adenoma/tratamento farmacológico , Antineoplásicos/uso terapêutico , Quinase 4 Dependente de Ciclina/antagonistas & inibidores , Quinase 6 Dependente de Ciclina/antagonistas & inibidores , Piperazinas/uso terapêutico , Neoplasias Hipofisárias/tratamento farmacológico , Piridinas/uso terapêutico , Adenoma/diagnóstico por imagem , Idoso , Antineoplásicos/farmacologia , Feminino , Humanos , Piperazinas/farmacologia , Neoplasias Hipofisárias/diagnóstico por imagem , Piridinas/farmacologia , Indução de Remissão
11.
Brain Struct Funct ; 223(1): 391-414, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28852859

RESUMO

Following fasting, satiety is accompanied by neuronal activation in brain areas including the central amygdalar nucleus (CEA). Since CEA is known to inhibit food intake, we hypothesized that CEA contributes to the termination of meal during refeeding. To better understand the organization of this satiety-related circuit, the interconnections of the CEA with refeeding-activated neuronal groups were elucidated using retrograde (cholera toxin-ß subunit, CTB) and anterograde (phaseolus vulgaris leucoagglutinin, PHA-L) tracers in male rats. C-Fos-immunoreactivity was used as marker of neuronal activation. The refeeding-activated input of the CEA primarily originated from the paraventricular thalamic, parasubthalamic and parabrachial nuclei. Few CTB-c-Fos double-labeled neurons were detected in the prefrontal cortex, lateral hypothalamic area, nucleus of the solitary tract (NTS) and the bed nuclei of the stria terminalis (BNST). Only few refeeding-activated proopiomelanocortin-producing neurons of the arcuate nucleus projected to the CEA. Anterograde tract tracing revealed a high density of PHAL-labeled axons contacted with refeeding-activated neurons in the BNST, lateral hypothalamic area, parasubthalamic, paraventricular thalamic and parabrachial nuclei and NTS; a low density of labeled axons was found in the paraventricular hypothalamic nucleus. Chemogenetic activation of the medial CEA (CEAm) inhibited food intake during the first hour of refeeding, while activation of lateral CEA had no effect. These data demonstrate the existence of reciprocal connections between the CEA and distinct refeeding-activated hypothalamic, thalamic and brainstem nuclei, suggesting the importance of short feedback loops in the regulation of satiety and importance of the CEAm in the regulation of food intake during refeeding.


Assuntos
Mapeamento Encefálico , Núcleo Central da Amígdala/citologia , Núcleo Central da Amígdala/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Resposta de Saciedade/fisiologia , Análise de Variância , Animais , Núcleo Arqueado do Hipotálamo/citologia , Núcleo Arqueado do Hipotálamo/fisiologia , Toxina da Cólera/metabolismo , Proteína Semelhante a ELAV 3/metabolismo , Ingestão de Alimentos/fisiologia , Jejum/fisiologia , Comportamento Alimentar/fisiologia , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Masculino , Fito-Hemaglutininas/metabolismo , Pró-Opiomelanocortina/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Transdução Genética
12.
Brain Struct Funct ; 223(3): 1329-1341, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29124350

RESUMO

Two anorexigenic peptides, thyrotropin-releasing hormone (TRH) and urocortin 3 (UCN3), are co-expressed in a continuous neuronal group that extends from the perifornical area to the bed nucleus of stria terminalis, raising the possibility that this cell group may be involved in the regulation of energy homeostasis. In this study, therefore, we tested the hypothesis that the TRH/UCN3 neurons regulate food intake by influencing feeding-related neuropeptide Y (NPY) and/or proopiomelanocortin (POMC) neurons in the arcuate nucleus (ARC). Triple-labeled immunofluorescent preparations demonstrated that only very few NPY neurons (4.3 ± 1.3%) were contacted by double-labeled TRH/UCN3 axons in the ARC. In contrast, more than half of the POMC neurons (52.4 ± 8.5%) were contacted by double-labeled axons. Immuno-electron microscopy demonstrated that the UCN3 axons established asymmetric synapses with POMC neurons, indicating the excitatory nature of these synaptic specializations. Patch clamp electrophysiology revealed that TRH and UCN3 have antagonistic effects on the POMC neurons. While UCN3 depolarizes and increases the firing rate of POMC neurons, TRH prevents these effects of UCN3. These data demonstrate that TRH/UCN3 neurons in the perifornical/BNST region establish abundant synaptic associations with the POMC neurons in the ARC and suggest a potentially important role for these neurons in the regulation of food intake through an antagonistic interaction between TRH and UCN3 on the electrophysiological properties of POMC neurons.


Assuntos
Núcleo Arqueado do Hipotálamo/citologia , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Núcleos Septais/citologia , Hormônio Liberador de Tireotropina/metabolismo , Urocortinas/metabolismo , Animais , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Vias Neurais/fisiologia , Neurônios/citologia , Neuropeptídeo Y , Pró-Opiomelanocortina/genética , Ratos , Ratos Wistar
13.
Endocrinology ; 159(2): 1159-1171, 2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29253128

RESUMO

Thyroid hormone (TH) is present in the systemic circulation and thus should affect all cells similarly in the body. However, tissues have a complex machinery that allows tissue-specific optimization of local TH action that calls for the assessment of TH action in a tissue-specific manner. Here, we report the creation of a TH action indicator (THAI) mouse model to study tissue-specific TH action. The model uses a firefly luciferase reporter readout in the context of an intact transcriptional apparatus and all elements of TH metabolism and transport and signaling. The THAI mouse allows the assessment of the changes of TH signaling in tissue samples or in live animals using bioluminescence, both in hypothyroidism and hyperthyroidism. Beyond pharmacologically manipulated TH levels, the THAI mouse is sufficiently sensitive to detect deiodinase-mediated changes of TH action in the interscapular brown adipose tissue (BAT) that preserves thermal homeostasis during cold stress. The model revealed that in contrast to the cold-induced changes of TH action in the BAT, the TH action in this tissue, at room temperature, is independent of noradrenergic signaling. Our data demonstrate that the THAI mouse can also be used to test TH receptor isoform-specific TH action. Thus, THAI mouse constitutes a unique model to study tissue-specific TH action within a physiological/pathophysiological context and test the performance of thyromimetics. In conclusion, THAI mouse provides an in vivo model to assess a high degree of tissue specificity of TH signaling, allowing alteration of tissue function in health and disease, independently of changes in circulating levels of TH.


Assuntos
Genes Reporter , Elementos de Resposta , Hormônios Tireóideos/farmacologia , Hormônios Tireóideos/fisiologia , Animais , Células Cultivadas , Feminino , Regulação da Expressão Gênica , Células HEK293 , Humanos , Hipertireoidismo/genética , Hipertireoidismo/metabolismo , Hipotireoidismo/genética , Hipotireoidismo/metabolismo , Iodeto Peroxidase/genética , Iodeto Peroxidase/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Modelos Animais , Especificidade de Órgãos/efeitos dos fármacos , Especificidade de Órgãos/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética
14.
Brain Res ; 1673: 64-71, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-28803831

RESUMO

Tanycytes are specialized glial cells lining the lateral walls and the floor of the third ventricle behind the optic chiasm. In addition to functioning as barrier cells, they also have an important role in the regulation of neuroendocrine axes and energy homeostasis. To determine whether tanycytes communicate with each other via Connexin 43 (Cx43) gap junctions, individual tanycytes were loaded with Lucifer yellow (LY) through a patch pipette. In all cases, LY filled a larger group of tanycytes as well as blood vessels adjacent to tanycyte processes. The Cx43-blocker, carbenoxolone, inhibited spreading of LY. The greatest density of Cx43-immunoreactive spots was observed in the cell membrane of α-tanycyte cell bodies. Cx43-immunoreactivity was also present in the membrane of ß-tanycyte cell bodies, but in lower density. Processes of both types of tanycytes also contained Cx43-immunoreactivity. At the ultrastructural level, Cx43-immunoreactivity was present in the cell membrane of all types of tanycytes including their ventricular surface, but gap junctions were more frequent among α-tanycytes. Cx43-immunoreactivity was also observed in the cell membrane between contacting tanycyte endfeet processes, and between tanycyte endfeet process and axon varicosities in the external zone of the median eminence and capillaries in the arcuate nucleus and median eminence. These results suggest that gap junctions are present not only among tanycytes, but also between tanycytes and the axons of hypophysiotropic neurons. Cx43 hemichannels may also facilitate the transport between tanycytes and extracellular fluids, including the cerebrospinal fluid, extracellular space of the median eminence and bloodstream.


Assuntos
Conexina 43/metabolismo , Células Ependimogliais/metabolismo , Junções Comunicantes/metabolismo , Animais , Vasos Sanguíneos/citologia , Vasos Sanguíneos/metabolismo , Carbenoxolona/farmacologia , Comunicação Celular/efeitos dos fármacos , Comunicação Celular/fisiologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Fármacos do Sistema Nervoso Central/farmacologia , Conexina 43/antagonistas & inibidores , Conexina 43/ultraestrutura , Células Ependimogliais/citologia , Células Ependimogliais/efeitos dos fármacos , Imunofluorescência , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/ultraestrutura , Masculino , Camundongos , Microscopia Eletrônica , Terceiro Ventrículo , Vimentina/metabolismo
15.
J Comp Neurol ; 525(3): 411-441, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-27503597

RESUMO

It is generally believed that proopiomelanocortin (POMC) is expressed exclusively by neurons in the adult rodent brain. Unbeknownst to most researchers, however, Pomc in situ hybridization studies in the rat show specific labeling in the ventral wall of the hypothalamic third ventricle, which is formed by specialized ependymal cells, called tanycytes. Here we characterized this non-neuronal POMC expression in detail using in situ hybridization and immunohistochemical techniques, and report two unique characteristics. First, POMC mRNA and precursor protein expression in non-neuronal cells varies to a great degree as to the extent and abundance of expression. In brains with low-level expression, POMC mRNA and protein was largely confined to a population of tanycytes within the infundibular stalk/caudal median eminence, termed here γ tanycytes, and a subset of closely located ß and α2 tanycytes. In brains with high-level expression, POMC mRNA and protein was observed in the vast majority of α2, ß, and γ tanycytes. This variability was observed in both adult males and females; of 41 rats between 8 and 15 weeks of age, 17 had low-, 9 intermediate-, and 15 high-level POMC expression in tanycytes. Second, unlike other known POMC-expressing cells, tanycytes rarely contained detectable levels of adrenocorticotropin or α-melanocyte-stimulating hormone. The results indicate either a dynamic spatiotemporal pattern whereby low and high POMC syntheses in tanycytes occur periodically in each brain, or marked interindividual differences that may persist throughout adulthood. Future studies are required to examine these possibilities and elucidate the physiologic importance of POMC in tanycytes. J. Comp. Neurol. 525:411-441, 2017. © 2016 Wiley Periodicals, Inc.


Assuntos
Células Ependimogliais/metabolismo , Hipotálamo/metabolismo , Hipófise/metabolismo , Pró-Opiomelanocortina/metabolismo , Animais , Células Ependimogliais/citologia , Feminino , Imunofluorescência , Expressão Gênica , Hipotálamo/citologia , Hibridização In Situ , Masculino , Microscopia Imunoeletrônica , Hipófise/citologia , RNA Mensageiro/metabolismo , Ratos Sprague-Dawley , Ratos Wistar
16.
Case Rep Endocrinol ; 2016: 6364203, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27651959

RESUMO

Carotid-cavernous fistulas (CCFs) are rare, pathologic communications of the carotid artery and the venous plexus of the cavernous sinus. They can develop spontaneously in certain at risk individuals or following traumatic head injury. Typical clinical manifestations include headache, proptosis, orbital pain, and diplopia. We report a case of bilateral carotid-cavernous fistulas associated with these symptoms and also with pituitary enlargement and hypopituitarism, which improved following surgical intervention. Arterialization of the cavernous sinus and elevated portal pressure may interfere with normal venous drainage and the conveyance of inhibiting and releasing hormones from the hypothalamus, resulting in pituitary enlargement and hypopituitarism. This condition should be considered in the differential diagnosis of hypopituitarism associated with anterior pituitary enlargement.

17.
Endocr Relat Cancer ; 23(12): 899-908, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27679736

RESUMO

Worldwide, the syndromes of paraganglioma (PGL), somatostatinoma (SOM) and early childhood polycythemia are described in only a few patients with somatic mutations in the hypoxia-inducible factor 2 alpha (HIF2A). This study provides detailed information about the clinical aspects and course of 7 patients with this syndrome and brings into perspective these experiences with the pertinent literature. Six females and one male presented at a median age of 28 years (range 11-46). Two were found to have HIF2A somatic mosaicism. No relatives were affected. All patients were diagnosed with polycythemia before age 8 and before PGL/SOM developed. PGLs were found at a median age of 17 years (range 8-38) and SOMs at 29 years (range 22-38). PGLs were multiple, recurrent and metastatic in 100, 100 and 29% of all cases, and SOMs in 40, 40 and 60%, respectively. All PGLs were primarily norepinephrine-producing. All patients had abnormal ophthalmologic findings and those with SOMs had gallbladder disease. Computed tomography (CT) and magnetic resonance imaging revealed cystic lesions at multiple sites and hemangiomas in 4 patients (57%), previously thought to be pathognomonic for von Hippel-Lindau disease. The most accurate radiopharmaceutical to detect PGL appeared to be [18F]-fluorodihydroxyphenylalanine ([18F]-FDOPA). Therefore, [18F]-FDOPA PET/CT, not [68Ga]-(DOTA)-[Tyr3]-octreotate ([68Ga]-DOTATATE) PET/CT is recommended for tumor localization and aftercare in this syndrome. The long-term prognosis of the syndrome is unknown. However, to date no deaths occurred after 6 years follow-up. Physicians should be aware of this unique syndrome and its diagnostic and therapeutic challenges.


Assuntos
Neoplasias das Glândulas Suprarrenais/patologia , Neoplasias Primárias Múltiplas/patologia , Neoplasias Pancreáticas/patologia , Paraganglioma/patologia , Policitemia/patologia , Somatostatinoma/patologia , Adolescente , Neoplasias das Glândulas Suprarrenais/complicações , Neoplasias das Glândulas Suprarrenais/diagnóstico , Neoplasias das Glândulas Suprarrenais/terapia , Adulto , Criança , Estudos de Coortes , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Primárias Múltiplas/complicações , Neoplasias Primárias Múltiplas/diagnóstico , Neoplasias Primárias Múltiplas/terapia , Neoplasias Pancreáticas/complicações , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/terapia , Paraganglioma/complicações , Paraganglioma/diagnóstico , Paraganglioma/terapia , Policitemia/complicações , Policitemia/diagnóstico , Policitemia/terapia , Estudos Retrospectivos , Somatostatinoma/complicações , Somatostatinoma/diagnóstico , Somatostatinoma/terapia , Síndrome , Adulto Jovem
18.
Neuropharmacology ; 110(Pt A): 198-210, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27084697

RESUMO

While dopamine (DA) neurons in the ventral tegmental area (VTA) drive the mesolimbic-reward pathway, confluent lines of evidence underscore the importance of transient receptor potential vanilloid (TRPV) channels as novel regulators of these neurons. Among the TRPV-subfamily, TRPV3 is of particular interest in reward, since active ingredients of flavour-enhancing spices in food serve as TRPV3 agonists and modulate DAergic neurotransmission. The nature of TRPV3 elements in the VTA and their role in driving the mesolimbic-DA-reward pathway has however, remained unexplored. We observed TRPV3 mRNA as well as TRPV3-immunoreactive neurons in the VTA of Wistar rats. We therefore explored whether these ion channels participate in modulating mesolimbic-DA reward pathway. In the posterior VTA (pVTA), 82 ± 2.6% of the TRPV3 neurons co-express tyrosine hydroxylase and 68 ± 5.5% of these neurons project to the nucleus accumbens shell (Acb shell). While ex vivo treatment of midbrain slices with TRPV3-agonist, thymol increased [Ca(2+)]i-activity in pVTA neurons, intra-pVTA injections of thymol in freely-moving, satiated rats enhanced positive reinforcement for active lever pressings in an operant chamber to self-administer sweet pellets. This behavior was attenuated by prior treatment with intra-Acb shell DA D1- and D2-like receptor antagonists. These results demonstrate a role for TRPV3 in driving mesolimbic-DA food-reward pathway, and underscores the importance of these channels in the VTA as key components processing reward.


Assuntos
Dopamina/metabolismo , Neurônios/metabolismo , Recompensa , Canais de Cátion TRPV/metabolismo , Área Tegmentar Ventral/metabolismo , Animais , Cálcio/metabolismo , Cátions Bivalentes/metabolismo , Linhagem Celular , Fármacos do Sistema Nervoso Central/farmacologia , Sacarose na Dieta , Antagonistas de Dopamina/farmacologia , Comportamento Alimentar/efeitos dos fármacos , Comportamento Alimentar/fisiologia , Masculino , Camundongos , Vias Neurais/citologia , Vias Neurais/efeitos dos fármacos , Vias Neurais/metabolismo , Neurônios/citologia , Neurônios/efeitos dos fármacos , Distribuição Aleatória , Ratos Wistar , Receptores Dopaminérgicos/metabolismo , Autoadministração , Canais de Cátion TRPV/agonistas , Timol/farmacologia , Técnicas de Cultura de Tecidos , Área Tegmentar Ventral/citologia , Área Tegmentar Ventral/efeitos dos fármacos
19.
J Comp Neurol ; 524(15): 3014-41, 2016 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-27018984

RESUMO

Cocaine- and amphetamine-regulated transcript (CART) has emerged as a potent anorectic agent. CART is widely distributed in the brain of mammals, amphibians, and teleosts, but the relevant information in avian brain is not available. In birds, CART inhibits food intake, whereas neuropeptide Y (NPY), a well-known orexigenic peptide, stimulates it. How these neuropeptides interact in the brain to regulate energy balance is not known. We studied the distribution of CART-immunoreactivity in the brain of zebra finch, Taeniopygia guttata, its interaction with NPY, and their response to dynamic energy states. CART-immunoreactive fibers were found in the subpallium, hypothalamus, midbrain, and brainstem. Conspicuous CART-immunoreactive cells were observed in the bed nucleus of the stria terminalis, hypothalamic paraventricular, supraoptic, dorsomedial, infundibular (IN), lateral hypothalamic, Edinger-Westphal, and parabrachial nuclei. Hypothalamic sections of fed, fasted, and refed animals were immunostained with cFos, NPY, and CART antisera. Fasting dramatically increased cFos- and NPY-immunoreactivity in the IN, followed by rapid reduction by 2 hours and restoration to normal fed levels 6-10 hours after refeeding. CART-immunoreactive fibers in IN showed a significant reduction during fasting and upregulation with refeeding. Within the IN, double immunofluorescence revealed that 94 ± 2.1% of NPY-immunoreactive neurons were contacted by CART-immunoreactive fibers and 96 ± 2.8% NPY-immunoreactive neurons expressed cFos during fasting. Compared to controls, superfused hypothalamic slices of fasted birds treated with CART-peptide showed a significant reduction (P < 0.001) in NPY-immunoreactivity in the IN. As in other vertebrates, CART in the brain of T. guttata may perform several functions, and has a particularly important role in the hypothalamic regulation of energy homeostasis. J. Comp. Neurol. 524:3014-3041, 2016. © 2016 Wiley Periodicals, Inc.


Assuntos
Proteínas Aviárias/metabolismo , Encéfalo/metabolismo , Jejum/metabolismo , Tentilhões/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neuropeptídeo Y/metabolismo , Animais , Proteínas Aviárias/genética , Western Blotting , Encéfalo/citologia , Ingestão de Alimentos/fisiologia , Tentilhões/anatomia & histologia , Imunofluorescência , Regulação da Expressão Gênica , Homeostase/fisiologia , Masculino , Proteínas do Tecido Nervoso/genética , Neurônios/citologia , Neurônios/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos Sprague-Dawley , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos
20.
J Comp Neurol ; 524(14): 2803-27, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-26918800

RESUMO

We hypothesized that brain regions showing neuronal activation after refeeding comprise major nodes in a satiety network, and tested this hypothesis with two sets of experiments. Detailed c-Fos mapping comparing fasted and refed rats was performed to identify candidate nodes of the satiety network. In addition to well-known feeding-related brain regions such as the arcuate, dorsomedial, and paraventricular hypothalamic nuclei, lateral hypothalamic area, parabrachial nucleus (PB), nucleus of the solitary tract and central amygdalar nucleus, other refeeding activated regions were also identified, such as the parastrial and parasubthalamic nuclei. To begin to understand the connectivity of the satiety network, the interconnectivity of PB with other refeeding-activated neuronal groups was studied following administration of anterograde or retrograde tracers into the PB. After allowing for tracer transport time, the animals were fasted and then refed before sacrifice. Refeeding-activated neurons that project to the PB were found in the agranular insular area; bed nuclei of terminal stria; anterior hypothalamic area; arcuate, paraventricular, and dorsomedial hypothalamic nuclei; lateral hypothalamic area; parasubthalamic nucleus; central amygdalar nucleus; area postrema; and nucleus of the solitary tract. Axons originating from the PB were observed to closely associate with refeeding-activated neurons in the agranular insular area; bed nuclei of terminal stria; anterior hypothalamus; paraventricular, arcuate, and dorsomedial hypothalamic nuclei; lateral hypothalamic area; central amygdalar nucleus; parasubthalamic nucleus; ventral posterior thalamic nucleus; area postrema; and nucleus of the solitary tract. These data indicate that the PB has bidirectional connections with most refeeding-activated neuronal groups, suggesting that short-loop feedback circuits exist in this satiety network. J. Comp. Neurol. 524:2803-2827, 2016. © 2016 Wiley Periodicals, Inc.


Assuntos
Rede Nervosa/anatomia & histologia , Rede Nervosa/fisiologia , Núcleos Parabraquiais/anatomia & histologia , Núcleos Parabraquiais/fisiologia , Resposta de Saciedade/fisiologia , Fatores Etários , Animais , Jejum/fisiologia , Hipotálamo/anatomia & histologia , Hipotálamo/fisiologia , Masculino , Vias Neurais/anatomia & histologia , Vias Neurais/fisiologia , Ratos , Ratos Wistar
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