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1.
Sci Rep ; 13(1): 11731, 2023 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-37474737

RESUMO

Neurodegenerative diseases are explained by progressive defects of cognitive function and memory. These defects of cognition and memory dysfunction can be induced by the loss of brain-derived neurotrophic factors (BDNF) signaling. Paeonia lactiflora is a traditionally used medicinal herb in Asian countries and some beneficial effects have been reported, including anti-oxidative, anti-inflammatory, anti-cancer activity, and potential neuroprotective effects recently. In this study, we found that suffruticosol A is a major compound in seeds of Paeonia lactiflora. When treated in a SH-SY5 cell line for measuring cell viability and cell survival, suffruticosol A increased cell viability (at 20 µM) and recovered scopolamine-induced neurodegenerative characteristics in the cells. To further confirm its neural amelioration effects in the animals, suffruticosol A (4 or 15 ng, twice a week) was administered into the third ventricle beside the brain of C57BL/6 mice for one month then the scopolamine was intraperitoneally injected into these mice to induce impairments of cognition and memory before conducting behavioral experiments. Central administration of suffruticosol A into the brain restored the memory and cognition behaviors in mice that received the scopolamine. Consistently, the central treatments of suffruticosol A showed rescued cholinergic deficits and BDNF signaling in the hippocampus of mice. Finally, we measured the long-term potentiation (LTP) in the hippocampal CA3-CA1 synapse to figure out the restoration of the synaptic mechanism of learning and memory. Bath application of suffruticosol A (40 µM) improved LTP impairment induced by scopolamine in hippocampal slices. In conclusion, the central administration of suffruticosol A ameliorated neuronal effects partly through elevated BDNF signaling.


Assuntos
Paeonia , Escopolamina , Camundongos , Animais , Escopolamina/farmacologia , Paeonia/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Camundongos Endogâmicos C57BL , Transdução de Sinais , Hipocampo/metabolismo , Transtornos da Memória/induzido quimicamente , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/metabolismo , Aprendizagem em Labirinto
2.
Brain ; 146(7): 2957-2974, 2023 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-37062541

RESUMO

Reactive astrogliosis is a hallmark of Alzheimer's disease (AD). However, a clinically validated neuroimaging probe to visualize the reactive astrogliosis is yet to be discovered. Here, we show that PET imaging with 11C-acetate and 18F-fluorodeoxyglucose (18F-FDG) functionally visualizes the reactive astrocyte-mediated neuronal hypometabolism in the brains with neuroinflammation and AD. To investigate the alterations of acetate and glucose metabolism in the diseased brains and their impact on the AD pathology, we adopted multifaceted approaches including microPET imaging, autoradiography, immunohistochemistry, metabolomics, and electrophysiology. Two AD rodent models, APP/PS1 and 5xFAD transgenic mice, one adenovirus-induced rat model of reactive astrogliosis, and post-mortem human brain tissues were used in this study. We further curated a proof-of-concept human study that included 11C-acetate and 18F-FDG PET imaging analyses along with neuropsychological assessments from 11 AD patients and 10 healthy control subjects. We demonstrate that reactive astrocytes excessively absorb acetate through elevated monocarboxylate transporter-1 (MCT1) in rodent models of both reactive astrogliosis and AD. The elevated acetate uptake is associated with reactive astrogliosis and boosts the aberrant astrocytic GABA synthesis when amyloid-ß is present. The excessive astrocytic GABA subsequently suppresses neuronal activity, which could lead to glucose uptake through decreased glucose transporter-3 in the diseased brains. We further demonstrate that 11C-acetate uptake was significantly increased in the entorhinal cortex, hippocampus and temporo-parietal neocortex of the AD patients compared to the healthy controls, while 18F-FDG uptake was significantly reduced in the same regions. Additionally, we discover a strong correlation between the patients' cognitive function and the PET signals of both 11C-acetate and 18F-FDG. We demonstrate the potential value of PET imaging with 11C-acetate and 18F-FDG by visualizing reactive astrogliosis and the associated neuronal glucose hypometablosim for AD patients. Our findings further suggest that the acetate-boosted reactive astrocyte-neuron interaction could contribute to the cognitive decline in AD.


Assuntos
Doença de Alzheimer , Camundongos , Humanos , Ratos , Animais , Doença de Alzheimer/metabolismo , Fluordesoxiglucose F18/metabolismo , Astrócitos/metabolismo , Radioisótopos de Carbono/metabolismo , Gliose/diagnóstico por imagem , Encéfalo/patologia , Tomografia por Emissão de Pósitrons/métodos , Ácido gama-Aminobutírico/metabolismo
3.
Exp Neurobiol ; 29(3): 219-229, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32624506

RESUMO

Understanding brain function-related neural circuit connectivity is essential for investigating how cognitive functions are decoded in neural circuits. Trans-synaptic viral vectors are useful for identifying neural synaptic connectivity because of their ability to be transferred from transduced cells to synaptically connected cells. However, concurrent labeling of multisynaptic inputs to postsynaptic neurons is impossible with currently available trans-synaptic viral vectors. Here, we report a neural circuit tracing system that can simultaneously label postsynaptic neurons with two different markers, the expression of which is defined by presynaptic input connectivity. This system, called "cFork (see fork)", includes delivering serotype 1-packaged AAV vectors (AAV1s) containing Cre or flippase recombinase (FlpO) into two different presynaptic brain areas, and AAV5 with a dual gene expression cassette in postsynaptic neurons. Our in vitro and in vivo tests showed that selective expression of two different fluorescence proteins, EGFP and mScarlet, in postsynaptic neurons could be achieved by AAV1-mediated anterograde trans-synaptic transfer of Cre or FlpO constructs. When this tracing system was applied to the somatosensory barrel field cortex (S1BF) or striatum innervated by multiple presynaptic inputs, postsynaptic neurons defined by presynaptic inputs were simultaneously labeled with EGFP or mScarlet. Our new anterograde tracing tool may be useful for elucidating the complex multisynaptic connectivity of postsynaptic neurons regulating diverse brain functions.

4.
BMC Public Health ; 20(1): 516, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32303215

RESUMO

BACKGROUND: Smoking and alcohol consumption are the most common social habits in patients with sialolithiasis. Moreover, obesity has been reported to have a significant association with poor oral hygiene, one of the causes of sialolithiasis. The purpose of this study was to evaluate the relationships among tobacco smoking, drinking alcohol, obesity and sialolithiasis in a Korean population. METHODS: The Korean National Health Insurance Service-Health Screening Cohort, which includes patients ≥40 years old, was assessed from 2002 to 2013. A total of 947 sialolithiasis participants were matched with 3788 control subjects at a ratio of 1:4 with respect to age group, sex, income group, region of residence, hypertension, diabetes, and dyslipidemia. We analyzed the participants' previous histories of smoking (current or past smokers compared to nonsmokers) and alcohol consumption (≥ 1 time per week compared to < 1 time per week) in the sialolithiasis and control groups. Obesity was measured using body mass index (BMI, kg/m2), which was categorized as < 18.5 (underweight), ≥ 18.5 and < 23 (normal), ≥ 23 and < 25 (overweight), ≥ 25 and < 30 (obese I), and ≥ 30 (obese II). Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression analyses. RESULTS: The rate of smoking was higher in the sialolithiasis group (32.4% [307/947]) than in the control group (29.1% [1103/3788], P = 0.047). The adjusted OR of smoking for the sialolithiasis group was 1.31 (95% CI = 1.08-1.59, P = 0.006). Alcohol consumption and obesity were not statistically significantly related to sialolithiasis. CONCLUSION: The odds of smoking were increased in sialolithiasis patients compared with control subjects in the population ≥ 40 years of age.


Assuntos
Consumo de Bebidas Alcoólicas/epidemiologia , Obesidade/epidemiologia , Cálculos das Glândulas Salivares/epidemiologia , Fumar Tabaco/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Estudos de Casos e Controles , Estudos de Coortes , Diabetes Mellitus , Dislipidemias , Feminino , Humanos , Hipertensão , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Razão de Chances , República da Coreia/epidemiologia , Fatores de Risco
5.
J Int Adv Otol ; 16(1): 40-46, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32209518

RESUMO

OBJECTIVES: To analyze the clinical characteristics of cochlear fistulas (CFs) and propose a new fistula classification system with regard to the cochlea. MATERIALS AND METHODS: A retrospective chart review was conducted between January 2008 and December 2015 to identify patients who had undergone surgery for cholesteatoma with an associated CF. The following data were collected: preoperative symptoms, findings of temporal bone computed tomography (TBCT), fistula stage, cholesteatoma classification, surgical technique, and pre- and postoperative pure-tone audiometry. RESULTS: We analyzed a total of 159 patients, out of which 9 (5.7%) were diagnosed with a CF. The average duration of the chronic otitis media was 19.8 years. Cholesteatomas that induced CF rarely existed in the nonaggressive state; recurrent otorrhea was observed in all but one of our subjects. All the patients with CF had a distinct origin of cholesteatoma that developed from the retraction of posterior pars tensa; further, 88.9% cholesteatomas extended to and filled the sinus tympani. Preoperative audiometry revealed total hearing loss in 4 (44.4%) patients. Further, five patients with residual hearing before surgery had stage I fistulas, and the bone conduction thresholds remained stable after surgery. CONCLUSION: Cochlear fistulas were often detected in patients with (1) a history of chronic otitis media (exceeding 10 years), (2) frequently recurring otorrhea, and (3) pars tensa cholesteatomas that extended to the posterior mesotympanum and filled the sinus tympani. Such patients can suffer from potentially severe and irreparable sensorineural hearing loss.


Assuntos
Colesteatoma da Orelha Média/cirurgia , Doenças Cocleares/patologia , Fístula/etiologia , Doenças do Labirinto/etiologia , Otite Média/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Audiometria de Tons Puros/métodos , Colesteatoma da Orelha Média/classificação , Colesteatoma da Orelha Média/complicações , Doença Crônica , Feminino , Fístula/classificação , Fístula/diagnóstico , Fístula/epidemiologia , Perda Auditiva Neurossensorial/diagnóstico , Perda Auditiva Neurossensorial/epidemiologia , Perda Auditiva Neurossensorial/etiologia , Humanos , Incidência , Doenças do Labirinto/diagnóstico , Doenças do Labirinto/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Osso Temporal/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Membrana Timpânica/patologia , Membrana Timpânica/cirurgia
6.
Allergy Asthma Immunol Res ; 12(1): 42-55, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31743963

RESUMO

PURPOSE: Various immune cells, including eosinophils and neutrophils, are known to contribute to the development of chronic rhinosinusitis with nasal polyps (CRSwNP). However, the current understanding of the role of neutrophils in the development of CRSwNP still remains unclear. Therefore, we investigated risk factors for refractoriness of CRSwNP in an Asian population. METHODS: Protein levels of 17 neutrophil-related mediators in nasal polyps (NPs) were determined by multiplex immunoassay, and exploratory factor analysis using principal component analysis was performed. Immunofluorescence analysis was conducted to detect human neutrophil elastase (HNE) or myeloperoxidase (MPO)-positive cells. Tissue eosinophilic nasal polyp (ENP) and tissue neutrophilia (Neuhigh) were defined as greater than 70 eosinophils and 20 HNE-positive cells, otherwise was classified into non-eosinophilic nasal polyp (NENP) and absence of tissue neutrophilia (Neulow). RESULTS: In terms of disease control status, NENP-Neulow patients showed the higher rate of disease control than NENP-Neuhigh and ENP-Neuhigh patients. Linear by linear association demonstrated the trend in refractoriness from NENP-Neulow to NENP-Neuhigh or ENP-Neulow to ENP-Neuhigh. When multiple logistic regression was performed, tissue neutrophilia (hazard ratio, 4.38; 95% confidence interval, 1.76-10.85) was found as the strongest risk factor for CRSwNP refractoriness. Additionally, exploratory factor analysis revealed that interleukin (IL)-18, interferon-γ, IL-1Ra, tumor necrosis factor-α, oncostatin M, and MPO were associated with good disease control status, whereas IL-36α and IL-1α were associated with refractory disease control status. In subgroup analysis, HNE-positive cells and IL-36α were significantly upregulated in the refractory group (P = 0.0132 and P = 0.0395, respectively), whereas MPO and IL-18 showed higher expression in the controlled group (P = 0.0002 and P = 0.0009, respectively). Moreover, immunofluorescence analysis revealed that IL-36R⁺HNE⁺-double positive cells were significantly increased in the refractory group compared to the control group. We also found that the ratio of HNE-positive cells to α1 anti-trypsin was increased in the refractory group. CONCLUSIONS: Tissue neutrophilia had an influence on treatment outcomes in the Asian CRSwNP patients. HNE-positive cells and IL-36α may be biomarkers for predicting refractoriness in Asians with CRSwNP. Additionally, imbalances in HNE and α1 anti-trypsin may be associated with pathophysiology of neutrophilic chronic rhinosinusitis.

7.
Yonsei Med J ; 60(6): 578-584, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31124342

RESUMO

PURPOSE: To evaluate the Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC) classification, a clinical scoring system, for predicting disease control status in chronic rhinosinusitis with nasal polyps (CRSwNP) and to investigate prognostic factors. MATERIALS AND METHODS: In total, 134 CRSwNP patients who underwent functional endoscopic sinus surgery after maximal medical treatment were enrolled. These patients were categorized into four groups according to JESREC classification: 1) non-eosinophilic CRSwNP (non-ECRSwNP), 2) mild eosinophilic CRSwNP (ECRSwNP), 3) moderate ECRSwNP, and 4) severe ECRSwNP. Disease control status among the patients was evaluated at 1 year after surgery, and the patients were divided into two groups (disease-controlled and disease-uncontrolled groups) for the investigation of prognostic factors. RESULTS: There was no significant difference in disease control status between non-ECRSwNP and ECRSwNP groups (p=0.970). Age, Lund-Mackay CT scores, global osteitis scores, tissue neutrophil count, and tissue eosinophil count were associated with disease control status. In subgroup analysis of the non-ECRSwNP group, only high tissue neutrophil count was related with disease control status, whereas for the ECRSwNP group, young age, high Lund-Mackay CT scores, high global osteitis scores, and high tissue and blood eosinophil counts were associated with disease control status. CONCLUSION: No difference in disease control status was identified between non-ECRSwNP and ECRSwNP cases. Tissue neutrophilia, however, appeared to be associated with disease control status in non-ECRSwNP cases, whereas tissue and blood eosinophilia was associated with ECRSwNP cases.


Assuntos
Pólipos Nasais/complicações , Rinite/complicações , Sinusite/complicações , Adulto , Doença Crônica , Eosinófilos/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pólipos Nasais/prevenção & controle , Neutrófilos/patologia , Prognóstico , Curva ROC , Rinite/prevenção & controle , Sinusite/prevenção & controle
8.
J Microbiol ; 56(7): 500-506, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29956123

RESUMO

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterial strain, designated 1-3-3-8T, was isolated from soil and characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain 1-3-3-8T belongs to the family Cytophagaceae of phylum Bacteroidetes and is most closely related to Hymenobacter paludis KBP-30T (96.8% similarity), Hymenobacter ocellatus Myx2105T (96.8%), Hymenobacter coalescens WW84T (95.6%), and Hymenobacter deserti ZLB-3T (95.4%). The G + C content of the genomic DNA of strain 1-3-3-8T was 63.6 mol%. The isolate contained C15:0 iso (28.4%), summed feature 4 (C17:1 anteiso B/C17:1 iso I; 18.9%), and C15:0 anteiso (17.6%) as major fatty acids, MK-7 as the predominant respiratory quinone, and sym-homospermidine as the predominant polyamine. The major polar lipids were phosphatidylethanolamine and an unidentified lipid. The phenotypic and chemotaxonomic data supported the affiliation of strain 1-3-3-8T with the genus Hymenobacter. The DNA-DNA relatedness between strain 1-3-3-8T and H. paludis KCTC 32237T and H. ocellatus DSM 11117T were 24.5 and 27.4% respectively, clearly showing that the isolate is not related to them at the species level. Overall, the novel strain could be differentiated from its phylogenetic neighbors on the basis of several phenotypic, genotypic, and chemotaxonomic features. Therefore, strain 1-3-3-8T represents a novel species of the genus Hymenobacter, for which the name Hymenobacter jeollabukensis sp. nov. has been proposed. The type strain is 1-3-3-8T (= KCTC 52741T = JCM 32192T).


Assuntos
Cytophagaceae/classificação , Cytophagaceae/isolamento & purificação , Microbiologia do Solo , Técnicas de Tipagem Bacteriana , Composição de Bases , Cytophagaceae/química , Cytophagaceae/genética , DNA Bacteriano/genética , Ácidos Graxos/análise , Fosfatidiletanolaminas/análise , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
9.
J Int Adv Otol ; 14(1): 144-147, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29764789

RESUMO

Eosinophilic otitis media (EOM) are intractable otitis media characterized by highly viscous secretions containing eosinophils in the middle ear. They are resistant to conventional medication and surgery. This condition occurs primarily in patients with bronchial asthma or allergic rhinitis and is often complicated by rhinosinusitis. Systemic and topical steroid therapies are effective treatments. However, long-term steroid therapy is often limited by a high risk of serious adverse effects. The use of topical steroids and otorrhea are bothersome when wearing hearing aids. Here, we report a case of intractable otitis media due to EOM. Otorrhea was controlled with topical steroids. Bone conduction hearing was stable for an extended period with anti-IgE monoclonal antibodies (omalizumab). An implantable bone conduction hearing aid was used for rehabilitation of conductive hearing loss.


Assuntos
Anticorpos Anti-Idiotípicos/uso terapêutico , Condução Óssea/fisiologia , Orelha Média/efeitos dos fármacos , Otite Média com Derrame/tratamento farmacológico , Anticorpos Monoclonais/uso terapêutico , Prótese Ancorada no Osso/efeitos adversos , Orelha Média/imunologia , Orelha Média/patologia , Eosinofilia/fisiopatologia , Eosinófilos/imunologia , Feminino , Auxiliares de Audição/efeitos adversos , Perda Auditiva/etiologia , Humanos , Fatores Imunológicos/uso terapêutico , Pessoa de Meia-Idade , Otite Média com Derrame/complicações , Otite Média com Derrame/imunologia , Resultado do Tratamento
10.
Eur Arch Otorhinolaryngol ; 274(10): 3789-3794, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28815307

RESUMO

Although thyroidectomy under local anesthesia with monitored anesthesia care (LA-MAC) has been reported, reports of neck dissections beyond level VI under LA-MAC in patients with thyroid cancer are rare. We aimed to analyze clinical data and patient satisfaction levels during thyroidectomy and selective neck dissection by comparing LA-MAC and general anesthesia (GA) in adult patients undergoing these surgeries for thyroid cancer. The 60 enrolled patients comprised 50 patients that underwent thyroidectomy and 10 that underwent selective neck dissection; 30 underwent thyroidectomy (n = 25) or selective neck dissection (n = 5) under LA-MAC and 30 (matched patients) underwent thyroidectomy (n = 25) or selective neck dissection (n = 5) under GA. Complaints of postoperative nausea, vomiting, throat discomfort, and voice changes were significantly fewer in the LA-MAC group than in the GA group. Postoperative pain, odynophagia, dyspnea, and patient satisfaction levels were not significantly different between groups. In the thyroidectomy group, postoperative nausea, vomiting, throat discomfort, and voice changes were less common with LA-MAC, whereas postoperative pain, odynophagia, dyspnea, and patient satisfaction levels were similar for both anesthesia methods. The selective neck dissection group showed no differences between the two anesthesia methods. No postoperative complications were reported in all patients. Our results suggest that LA-MAC can be routinely used for select cases of thyroidectomy and is feasible for selective neck dissection beyond level VI with regard to postoperative discomfort, patient satisfaction levels, and safety. However, further investigations are necessary to clarify these findings.


Assuntos
Anestesia Local , Esvaziamento Cervical , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia , Adulto , Anestesia Local/efeitos adversos , Anestesia Local/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Intraoperatória/métodos , Esvaziamento Cervical/efeitos adversos , Esvaziamento Cervical/métodos , Dor Pós-Operatória/diagnóstico , Satisfação do Paciente , Náusea e Vômito Pós-Operatórios/diagnóstico , Tireoidectomia/efeitos adversos , Tireoidectomia/métodos , Resultado do Tratamento , Adulto Jovem
11.
Medicine (Baltimore) ; 96(22): e6873, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28562535

RESUMO

Bimaxillary surgery is the traditional treatment of choice for correcting class III malocclusion which is reported to cause an alteration of oropharyngeal structures and upper airway narrowing that might be a predisposing factor for obstructive sleep apnea (OSA). This study aimed to analyze sleep parameters in class III malocclusion subjects and ascertain the prevalence of snoring or OSA following bimaxillary surgery.A total of 22 patients with Le Fort I osteotomy and mandibular setback for class III malocclusion were prospectively enrolled. All patients received endoscopic examination, cephalometry, 3-dimensional computed tomography (3D-CT), and sleep study twice at 1 month before and 3 months after surgery.The patient population consisted of 5 males and 17 females with a mean body mass index of 22.5 kg/m and mean age of 22.1 years. No patients complained of sleep-related symptoms, and the results of sleep study showed normal values before surgery. Three patients (13%) were newly diagnosed with mild or moderate OSA and 6 patients (27%) showed increased loudness of snoring (over 40 dB) after bimaxillary surgery. According to cephalometric analysis and 3D-CT results, the retropalatal and retroglossal areas were significantly narrowed in class III malocclusion patients, showing snoring and sleep apnea after surgery. In addition, the total volume of the upper airway was considerably reduced following surgery in the same patients.Postoperative narrowing of the upper airway and a reduction of total upper airway volume can be induced, and causes snoring and OSA in class III malocclusion subjects following bimaxillary surgery.


Assuntos
Má Oclusão Classe III de Angle/cirurgia , Maxila/cirurgia , Faringe/diagnóstico por imagem , Complicações Pós-Operatórias/diagnóstico por imagem , Síndromes da Apneia do Sono/complicações , Síndromes da Apneia do Sono/diagnóstico por imagem , Cefalometria , Feminino , Humanos , Imageamento Tridimensional , Masculino , Má Oclusão Classe III de Angle/complicações , Má Oclusão Classe III de Angle/diagnóstico por imagem , Má Oclusão Classe III de Angle/epidemiologia , Tamanho do Órgão , Procedimentos Ortopédicos/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Prevalência , Estudos Prospectivos , Síndromes da Apneia do Sono/epidemiologia , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Adulto Jovem
12.
Pflugers Arch ; 467(12): 2461-72, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26100674

RESUMO

Na(+)/Ca(2+) exchangers are key players for Ca(2+) clearance in pancreatic ß-cells, but their molecular determinants and roles in insulin secretion are not fully understood. In the present study, we newly discovered that the Li(+)-permeable Na(+)/Ca(2+) exchangers (NCLX), which were known as mitochondrial Na(+)/Ca(2+) exchangers, contributed to the Na(+)-dependent Ca(2+) movement across the plasma membrane in rat INS-1 insulinoma cells. Na(+)/Ca(2+) exchange activity by NCLX was comparable to that by the Na(+)/Ca(2+) exchanger, NCX. We also confirmed the presence of NCLX proteins on the plasma membrane using immunocytochemistry and cell surface biotinylation experiments. We further investigated the role of NCLX on exocytosis function by measuring the capacitance increase in response to repetitive depolarization. Small interfering (si)RNA-mediated downregulation of NCLX did not affect the initial exocytosis, but significantly suppressed sustained exocytosis and recovery of exocytosis. XIP (NCX inhibitory peptide) or Na(+) replacement for inhibiting Na(+)-dependent Ca(2+) clearance also selectively suppressed sustained exocytosis. Consistent with the idea that sustained exocytosis requires ATP-dependent vesicle recruitment, mitochondrial function, assessed by mitochondrial membrane potential (ΔΨ), was impaired by siNCLX or XIP. However, depolarization-induced exocytosis was hardly affected by changes in intracellular Na(+) concentration, suggesting a negligible contribution of mitochondrial Na(+)/Ca(2+) exchanger. Taken together, our data indicate that Na(+)/Ca(2+) exchanger-mediated Ca(2+) clearance mediated by NCLX and NCX is crucial for optimizing mitochondrial function, which in turn contributes to vesicle recruitment for sustained exocytosis in pancreatic ß-cells.


Assuntos
Cálcio/metabolismo , Membrana Celular/metabolismo , Exocitose , Células Secretoras de Insulina/metabolismo , Lítio/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Potenciais de Ação , Animais , Linhagem Celular Tumoral , Células Cultivadas , Células Secretoras de Insulina/efeitos dos fármacos , Potencial da Membrana Mitocondrial , Camundongos , Camundongos Endogâmicos C57BL , Peptídeos/farmacologia , Ratos , Trocador de Sódio e Cálcio/genética
13.
Proc Natl Acad Sci U S A ; 110(31): 12673-8, 2013 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-23858470

RESUMO

Leptin is a pivotal regulator of energy and glucose homeostasis, and defects in leptin signaling result in obesity and diabetes. The ATP-sensitive potassium (K(ATP)) channels couple glucose metabolism to insulin secretion in pancreatic ß-cells. In this study, we provide evidence that leptin modulates pancreatic ß-cell functions by promoting K(ATP) channel translocation to the plasma membrane via AMP-activated protein kinase (AMPK) signaling. K(ATP) channels were localized mostly to intracellular compartments of pancreatic ß-cells in the fed state and translocated to the plasma membrane in the fasted state. This process was defective in leptin-deficient ob/ob mice, but restored by leptin treatment. We discovered that the molecular mechanism of leptin-induced AMPK activation involves canonical transient receptor potential 4 and calcium/calmodulin-dependent protein kinase kinase ß. AMPK activation was dependent on both leptin and glucose concentrations, so at optimal concentrations of leptin, AMPK was activated sufficiently to induce K(ATP) channel trafficking and hyperpolarization of pancreatic ß-cells in a physiological range of fasting glucose levels. There was a close correlation between phospho-AMPK levels and ß-cell membrane potentials, suggesting that AMPK-dependent K(ATP) channel trafficking is a key mechanism for regulating ß-cell membrane potentials. Our results present a signaling pathway whereby leptin regulates glucose homeostasis by modulating ß-cell excitability.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Células Secretoras de Insulina/metabolismo , Leptina/metabolismo , Potenciais da Membrana/fisiologia , Transdução de Sinais/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Proteínas Quinases Ativadas por AMP/genética , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Glucose/metabolismo , Homeostase/fisiologia , Células Secretoras de Insulina/citologia , Leptina/genética , Camundongos , Camundongos Obesos , Transporte Proteico/fisiologia , ATPase Trocadora de Sódio-Potássio/genética , Canais de Cátion TRPC/genética , Canais de Cátion TRPC/metabolismo
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