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1.
Sci Rep ; 11(1): 10962, 2021 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-34040115

RESUMO

Neuropeptides have been reported to regulate progenitor proliferation and neurogenesis in the central nervous system. However, these studies have typically been conducted using pharmacological agents in ex vivo preparations, and in vivo evidence for their developmental function is generally lacking. Recent scRNA-Seq studies have identified multiple neuropeptides and their receptors as being selectively expressed in neurogenic progenitors of the embryonic mouse and human retina. This includes Sstr2, whose ligand somatostatin is transiently expressed by immature retinal ganglion cells. By analyzing retinal explants treated with selective ligands that target these receptors, we found that Sstr2-dependent somatostatin signaling induces a modest, dose-dependent inhibition of photoreceptor generation, while correspondingly increasing the relative fraction of primary progenitor cells. These effects were confirmed by scRNA-Seq analysis of retinal explants but abolished in Sstr2-deficient retinas. Although no changes in the relative fraction of primary progenitors or photoreceptor precursors were observed in Sstr2-deficient retinas in vivo, scRNA-Seq analysis demonstrated accelerated differentiation of neurogenic progenitors. We conclude that, while Sstr2 signaling may act to negatively regulate retinal neurogenesis in combination with other retinal ganglion cell-derived secreted factors such as Shh, it is dispensable for normal retinal development.


Assuntos
Proteínas do Olho/fisiologia , Neurogênese/fisiologia , Neuropeptídeos/fisiologia , Receptores de Somatostatina/fisiologia , Retina/citologia , Animais , Relação Dose-Resposta a Droga , Proteínas do Olho/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Inativação de Genes , Idade Gestacional , Humanos , Ligantes , Camundongos , Camundongos Knockout , Neuropeptídeos/agonistas , Neuropeptídeos/antagonistas & inibidores , Neuropeptídeos/farmacologia , Fenótipo , Células Fotorreceptoras de Vertebrados/efeitos dos fármacos , Células Fotorreceptoras de Vertebrados/metabolismo , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/efeitos dos fármacos , Retina/embriologia , Transdução de Sinais/fisiologia , Análise de Célula Única
2.
Int J Neuropsychopharmacol ; 23(1): 53-65, 2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-31563948

RESUMO

BACKGROUND: Evidence from anatomical, pharmacological, and genetic studies supports a role for the neuropeptide melanin concentrating hormone system in modulating emotional and cognitive functions. Genome-wide association studies revealed a potential association between the melanin concentrating hormone receptor (MCHR1) gene locus and schizophrenia, and the largest genome-wide association study conducted to date shows a credible genome-wide association. METHODS: We analyzed MCHR1 and pro-melanin concentrating hormone RNA-Seq expression in the prefrontal cortex in schizophrenia patients and healthy controls. Disruptions in the melanin concentrating hormone system were modeled in the mouse brain by germline deletion of MCHR1 and by conditional ablation of melanin concentrating hormone expressing neurons using a Cre-inducible diphtheria toxin system. RESULTS: MCHR1 expression is decreased in the prefrontal cortex of schizophrenia samples (false discovery rate (FDR) P < .05, CommonMind and PsychEncode combined datasets, n = 901) while pro-melanin concentrating hormone is below the detection threshold. MCHR1 expression decreased with aging (P = 6.6E-57) in human dorsolateral prefrontal cortex. The deletion of MCHR1 was found to lead to behavioral abnormalities mimicking schizophrenia-like phenotypes: hyperactivity, increased stereotypic and repetitive behavior, social impairment, impaired sensorimotor gating, and disrupted cognitive functions. Conditional ablation of pro-melanin concentrating hormone neurons increased repetitive behavior and produced a deficit in sensorimotor gating. CONCLUSIONS: Our study indicates that early disruption of the melanin concentrating hormone system interferes with neurodevelopmental processes, which may contribute to the pathogenesis of schizophrenia. Further neurobiological research on the developmental timing and circuits that are affected by melanin concentrating hormone may lead to a therapeutic target for early prevention of schizophrenia.


Assuntos
Hormônios Hipotalâmicos/metabolismo , Melaninas/metabolismo , Transtornos da Memória/fisiopatologia , Hormônios Hipofisários/metabolismo , Córtex Pré-Frontal/metabolismo , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/metabolismo , Esquizofrenia/metabolismo , Esquizofrenia/fisiopatologia , Filtro Sensorial/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Comportamento Animal/fisiologia , Criança , Pré-Escolar , Modelos Animais de Doenças , Feminino , Feto , Humanos , Lactente , Masculino , Transtornos da Memória/etiologia , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Esquizofrenia/complicações , Adulto Jovem
3.
Artigo em Inglês | MEDLINE | ID: mdl-29409919

RESUMO

This study investigated whether sst2 gene deletion interacts with age and chronic stress exposure to produce exacerbated emotional and cognitive ageing. Middle-aged (10-12 month) sst2 knockout (sst2KO) and wild-type (WT) mice underwent an unpredictable chronic mild stress (UCMS) procedure for 6 weeks or no stress for control groups. This was followed by a battery of tests to assess emotional and cognitive functions and neuroendocrine status (CORT level). A re-evaluation was performed 6 months later (i.e. with 18-month-old mice). UCMS reproduced neuroendocrine and behavioral features of stress-related disorders such as elevated circulating CORT levels, physical deteriorations, increased anxiety- and depressive-like behaviors and working memory impairments. sst2KO mice displayed behavioral alterations which were similar to stressed WT and exhibited exacerbated changes following UCMS exposure. The evaluations performed in the older mice showed significant long-term effects of UCMS exposure. Old sst2KO mice previously exposed to UCMS exhibited spatial learning and memory accuracy impairments and high levels of anxiety-like behaviors which drastically added to the effects of normal ageing. Spatial abilities and emotionality scores (mean z-scores) measured both at the UCMS outcome and 6 months later were correlated with the initially measured CORT levels in middle-age. The present findings indicate that the deletion of the sst2 receptor gene produces chronic hypercorticosteronemia and exacerbates sensitivity to stressors which over time, have consequences on ageing brain function processes.


Assuntos
Envelhecimento/metabolismo , Envelhecimento/psicologia , Cognição/fisiologia , Emoções/fisiologia , Receptores de Somatostatina/deficiência , Estresse Psicológico/metabolismo , Animais , Ansiedade/metabolismo , Doença Crônica , Disfunção Cognitiva/metabolismo , Corticosterona/sangue , Depressão/metabolismo , Modelos Animais de Doenças , Deleção de Genes , Transtornos da Memória/metabolismo , Memória de Curto Prazo/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Somatostatina/genética
4.
Behav Brain Res ; 316: 271-278, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-27633558

RESUMO

In order to decipher the functional involvement of melanin-concentrating hormone 1 (MCH1) receptors in the control of feeding and foraging behaviors, mice with constitutive deletion of MCH1 receptors MCH1R -/- or knockout (KO) were studied and compared to age-matched littermate control mice (MCH1R +/+ or wildtype (WT)). Several challenges to food-motivated behaviors of food-restricted WT and KO mice were implemented. There were no differences between genotypes in the acquisition of a nose-poke response that produced food or in a discrimination between a response that produced food and one that did not. There were also no genotype differences in the rate of extinction of a food-motivated response. However, during the first day of extinction, foraging behaviors were increased significantly more in KO than in WT mice. Likewise, when the response requirement to obtain food was progressively increased, KO mice made significantly more food-directed responses than WT mice. Although adulteration of food with quinine did not suppress food-directed behavior in either genotype when the mice were food-restricted, manipulation of the degree of food-deprivation resulted in suppression of behavior of WT mice without suppressing the behavior of KO mice. Although response-produced foot shock suppressed food-maintained responding of both WT and KO mice, equipotent levels of shock (based upon psychophysical thresholds) suppressed behavior of WT mice without suppressing behavior of the KO mice. Finally, under a Vogel conflict procedure, KO mice had significantly higher levels of both punished and non-punished food maintained responding. Thus, the data from challenges with both appetitive and noxious stimulus challenges support the conclusion that mice with constitutive deletion of MCH1Rs have increased food seeking motivation that is coincident with their higher metabolism. The data also highlight important differences in the biological impact of MCH1 receptor KO and MCH1 receptor antagonism.


Assuntos
Ingestão de Alimentos/genética , Comportamento Alimentar/fisiologia , Receptores de Somatostatina/deficiência , Reforço Psicológico , Animais , Animais Recém-Nascidos , Biofísica , Condicionamento Operante/fisiologia , Estimulação Elétrica , Feminino , Alimentos , Privação de Alimentos , Masculino , Camundongos , Camundongos Transgênicos , Quinina/administração & dosagem , Receptores de Somatostatina/genética , Saciação/fisiologia
5.
Br J Pharmacol ; 173(18): 2739-51, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27400775

RESUMO

BACKGROUND AND PURPOSE: Melanin-concentrating hormone (MCH) is an orexigen, and while rodents express one MCH receptor (MCH1 receptor), humans, non-human primates and dogs express two MCH receptors (MCH1 and MCH2 ). MCH1 receptor antagonists have been developed for the treatment of obesity and lower body weight in rodents. However, the mechanisms for the body weight loss and whether MCH1 receptor antagonism can lower body weight in species expressing both MCH receptors are not fully understood. EXPERIMENTAL APPROACH: A novel recently identified potent MCH1 receptor antagonist, AZD1979, was studied in wild type and Mchr1 knockout (KO) mice and by using pair-feeding and indirect calorimetry in diet-induced obese (DIO) mice. The effect of AZD1979 on body weight was also studied in beagle dogs. KEY RESULTS: AZD1979 bound to MCH1 receptors in the CNS and dose-dependently reduced body weight in DIO mice leading to improved homeostasis model assessment-index of insulin sensitivity. AZD1979 did not affect food intake or body weight in Mchr1 KO mice demonstrating specificity for the MCH1 receptor mechanism. In DIO mice, initial AZD1979-mediated body weight loss was driven by decreased food intake, but an additional component of preserved energy expenditure was apparent in pair-feeding and indirect calorimetry studies. AZD1979 also dose-dependently reduced body weight in dogs. CONCLUSION AND IMPLICATIONS: AZD1979 is a novel potent MCH1 receptor antagonist that affects both food intake and energy expenditure. That AZD1979 also lowers body weight in a species expressing both MCH receptors holds promise for the use of MCH1 receptor antagonists for the treatment of human obesity.


Assuntos
Azetidinas/farmacologia , Peso Corporal/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Oxidiazóis/farmacologia , Receptores de Somatostatina/antagonistas & inibidores , Animais , Azetidinas/administração & dosagem , Azetidinas/química , Cães , Relação Dose-Resposta a Droga , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estrutura Molecular , Oxidiazóis/administração & dosagem , Oxidiazóis/química , Receptores de Somatostatina/deficiência , Relação Estrutura-Atividade
6.
J Med Chem ; 59(3): 1116-39, 2016 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-26736071

RESUMO

Aiming to discover melanin-concentrating hormone receptor 1 (MCHR1) antagonists with improved safety profiles, we hypothesized that the aliphatic amine employed in most antagonists reported to date could be removed if the bicyclic motif of the compound scaffold interacted with Asp123 and/or Tyr272 of MCHR1. We excluded aliphatic amines from our compound designs, with a cutoff value of pK(a) < 8, and explored aliphatic amine-free MCHR1 antagonists in a CNS-oriented chemical space limited by four descriptors (TPSA, ClogP, MW, and HBD count). Screening of novel bicyclic motifs with high intrinsic binding affinity for MCHR1 identified the imidazo[1,2-a]pyridine ring (represented in compounds 6a and 6b), and subsequent cyclization of the central aliphatic amide linkage led to the discovery of a potent, orally bioavailable MCHR1 antagonist 4-[(4-chlorobenzyl)oxy]-1-(2-cyclopropyl-3-methylimidazo[1,2-a]pyridin-6-yl)pyridin-2(1H)-one 10a. It exhibited low potential for hERG inhibition and phospholipidosis induction as well as sufficient brain concentration to exert antiobesity effects in diet-induced obese rats.


Assuntos
Fármacos Antiobesidade/farmacologia , Imidazóis/química , Imidazóis/farmacologia , Obesidade/tratamento farmacológico , Piridonas/química , Piridonas/farmacologia , Receptores de Somatostatina/antagonistas & inibidores , Animais , Fármacos Antiobesidade/síntese química , Fármacos Antiobesidade/química , Células CHO , Cricetulus , Relação Dose-Resposta a Droga , Humanos , Imidazóis/síntese química , Masculino , Estrutura Molecular , Piridonas/síntese química , Ratos , Ratos Endogâmicos F344 , Ratos Sprague-Dawley , Receptores de Somatostatina/deficiência , Relação Estrutura-Atividade
7.
Physiol Behav ; 152(Pt B): 402-7, 2015 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-26048303

RESUMO

Exposure to environmental cues associated with food can evoke eating behavior in the absence of hunger. This capacity for reward cues to promote feeding behaviors under sated conditions can be examined in the laboratory using cue-potentiated feeding (CPF). The orexigenic neuropeptide Melanin Concentrating Hormone (MCH) is expressed throughout brain circuitry critical for CPF. We examined whether deletion of the MCH receptor, MCH-1R, would in KO mice disrupt overeating in the presence of a Pavlovian CS+ associated with sucrose delivery. While both wild-type controls and KO mice showed comparable food magazine approach responses during the CPF test, MCH-1R deletion significantly impaired the ability of the CS+ to evoke overeating of sucrose under satiety. Through the use of a refined analysis of meal intake, it was revealed that this disruption to overeating behavior in KO mice reflected a reduction in the capacity for the CS+ to initiate and maintain bursts of licking behavior. These findings suggest that overeating during CPF requires intact MCH-1R signaling and may be due to an influence of the CS+ on the palatability of food and on regulatory mechanisms of peripheral control. Thus, disruptions to MCH-1R signaling may be a useful pharmacological tool to inhibit this form of overeating behavior.


Assuntos
Sinais (Psicologia) , Comportamento Alimentar/fisiologia , Alimentos , Hiperfagia/fisiopatologia , Receptores de Somatostatina/deficiência , Animais , Condicionamento Clássico/fisiologia , Sacarose Alimentar , Comportamento Alimentar/psicologia , Hiperfagia/psicologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Atividade Motora/fisiologia , Boca/fisiologia , Receptores de Somatostatina/genética , Saciação/fisiologia , Deleção de Sequência
9.
Gastroenterology ; 148(7): 1452-65, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25683115

RESUMO

BACKGROUND & AIMS: The KRAS gene is mutated in most pancreatic ductal adenocarcinomas (PDAC). Expression of this KRAS oncoprotein in mice is sufficient to initiate carcinogenesis but not progression to cancer. Activation of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) is required for KRAS for induction and maintenance of PDAC in mice. The somatostatin receptor subtype 2 (sst2) inhibits PI3K, but sst2 expression is lost during the development of human PDAC. We investigated the effects of sst2 loss during KRAS-induced PDAC development in mice. METHODS: We analyzed tumor growth in mice that expressed the oncogenic form of KRAS (KRAS(G12D)) in pancreatic precursor cells, as well as sst2+/- and sst2-/-, and in crossed KRAS(G12D);sst2+/- and KRAS(G12D);sst2-/- mice. Pancreatic tissues and acini were collected and assessed by histologic, immunoblot, immunohistochemical, and reverse-transcription polymerase chain reaction analyses. We also compared protein levels in paraffin-embedded PDAC samples from patients vs heathy pancreatic tissues from individuals without pancreatic cancer. RESULTS: In sst2+/- mice, PI3K was activated and signaled via AKT (PKB; protein kinase B); when these mice were crossed with KRAS(G12D) mice, premalignant lesions, tumors, and lymph node metastases developed more rapidly than in KRAS(G12D) mice. In crossed KRAS(G12D);sst2+/- mice, activation of PI3K signaling via AKT resulted in activation of nuclear factor-κB (NF-κB), which increased KRAS activity and its downstream pathways, promoting initiation and progression of neoplastic lesions. We found this activation loop to be mediated by PI3K-induced production of the chemokine CXCL16. Administration of a CXCL16-neutralizing antibody to KRAS(G12D) mice reduced activation of PI3K signaling to AKT and NF-κB, blocking carcinogenesis. Levels of CXCL16 and its receptor CXCR6 were significantly higher in PDAC tissues and surrounding acini than in healthy pancreatic tissues from mice or human beings. In addition, expression of sst2 was progressively lost, involving increased PI3K activity, in mouse lesions that expressed KRAS(G12D) and progressed to PDAC. CONCLUSIONS: Based on analyses of mice, loss of sst2 from pancreatic tissues activates PI3K signaling via AKT, leading to activation of NF-κB, amplification of oncogenic KRAS signaling, increased expression of CXCL16, and pancreatic tumor formation. CXCL16 might be a therapeutic target for PDAC.


Assuntos
Carcinoma Ductal Pancreático/enzimologia , Proliferação de Células , Quimiocina CXCL6/metabolismo , Mutação , Neoplasias Pancreáticas/enzimologia , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/genética , Receptores de Somatostatina/deficiência , Transdução de Sinais , Animais , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/imunologia , Carcinoma Ductal Pancreático/secundário , Estudos de Casos e Controles , Linhagem Celular Tumoral , Quimiocina CXCL16 , Quimiocinas CXC/metabolismo , Modelos Animais de Doenças , Predisposição Genética para Doença , Humanos , Metástase Linfática , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/metabolismo , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/imunologia , Neoplasias Pancreáticas/patologia , Fenótipo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores Depuradores/metabolismo , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Fatores de Tempo , Transfecção , Carga Tumoral , Regulação para Cima
10.
PLoS One ; 9(11): e112109, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25427253

RESUMO

We have generated a novel monoclonal antibody targeting human FGFR1c (R1c mAb) that caused profound body weight and body fat loss in diet-induced obese mice due to decreased food intake (with energy expenditure unaltered), in turn improving glucose control. R1c mAb also caused weight loss in leptin-deficient ob/ob mice, leptin receptor-mutant db/db mice, and in mice lacking either the melanocortin 4 receptor or the melanin-concentrating hormone receptor 1. In addition, R1c mAb did not change hypothalamic mRNA expression levels of Agrp, Cart, Pomc, Npy, Crh, Mch, or Orexin, suggesting that R1c mAb could cause food intake inhibition and body weight loss via other mechanisms in the brain. Interestingly, peripherally administered R1c mAb accumulated in the median eminence, adjacent arcuate nucleus and in the circumventricular organs where it activated the early response gene c-Fos. As a plausible mechanism and coinciding with the initiation of food intake suppression, R1c mAb induced hypothalamic expression levels of the cytokines Monocyte chemoattractant protein 1 and 3 and ERK1/2 and p70 S6 kinase 1 activation.


Assuntos
Anticorpos Monoclonais/farmacologia , Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Órgãos Circunventriculares/efeitos dos fármacos , Intolerância à Glucose/tratamento farmacológico , Hipotálamo/efeitos dos fármacos , Obesidade/tratamento farmacológico , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/antagonistas & inibidores , Animais , Núcleo Arqueado do Hipotálamo/metabolismo , Núcleo Arqueado do Hipotálamo/fisiopatologia , Quimiocina CCL2/agonistas , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Quimiocina CCL7/agonistas , Quimiocina CCL7/genética , Quimiocina CCL7/metabolismo , Órgãos Circunventriculares/metabolismo , Órgãos Circunventriculares/fisiopatologia , Ingestão de Alimentos/efeitos dos fármacos , Metabolismo Energético , Feminino , Regulação da Expressão Gênica , Intolerância à Glucose/genética , Intolerância à Glucose/metabolismo , Intolerância à Glucose/fisiopatologia , Humanos , Hipotálamo/metabolismo , Hipotálamo/fisiopatologia , Leptina/deficiência , Leptina/genética , Camundongos , Camundongos Knockout , Camundongos Obesos , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Obesidade/genética , Obesidade/metabolismo , Obesidade/fisiopatologia , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Receptor Tipo 4 de Melanocortina/deficiência , Receptor Tipo 4 de Melanocortina/genética , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/genética , Proteínas Quinases S6 Ribossômicas 70-kDa/genética , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Fator de Resposta Sérica/agonistas , Fator de Resposta Sérica/genética , Fator de Resposta Sérica/metabolismo , Transdução de Sinais
11.
PLoS One ; 9(9): e108146, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25268135

RESUMO

Hair cells and spiral ganglion neurons of the mammalian auditory system do not regenerate, and their loss leads to irreversible hearing loss. Aminoglycosides induce auditory hair cell death in vitro, and evidence suggests that phosphatidylinositol-3-kinase/Akt signaling opposes gentamicin toxicity via its downstream target, the protein kinase Akt. We previously demonstrated that somatostatin-a peptide with hormone/neurotransmitter properties-can protect hair cells from gentamicin-induced hair cell death in vitro, and that somatostatin receptors are expressed in the mammalian inner ear. However, it remains unknown how this protective effect is mediated. In the present study, we show a highly significant protective effect of octreotide (a drug that mimics and is more potent than somatostatin) on gentamicin-induced hair cell death, and increased Akt phosphorylation in octreotide-treated organ of Corti explants in vitro. Moreover, we demonstrate that somatostatin receptor-1 knockout mice overexpress somatostatin receptor-2 in the organ of Corti, and are less susceptible to gentamicin-induced hair cell loss than wild-type or somatostatin-1/somatostatin-2 double-knockout mice. Finally, we show that octreotide affects auditory hair cells, enhances spiral ganglion neurite number, and decreases spiral ganglion neurite length.


Assuntos
Células Ciliadas Auditivas/metabolismo , Perda Auditiva/genética , Receptores de Somatostatina/genética , Gânglio Espiral da Cóclea/metabolismo , Animais , Morte Celular/efeitos dos fármacos , Regulação da Expressão Gênica , Gentamicinas , Células Ciliadas Auditivas/efeitos dos fármacos , Células Ciliadas Auditivas/patologia , Perda Auditiva/induzido quimicamente , Perda Auditiva/fisiopatologia , Perda Auditiva/prevenção & controle , Camundongos , Camundongos Knockout , Neuritos/efeitos dos fármacos , Neuritos/metabolismo , Neuritos/ultraestrutura , Octreotida/farmacologia , Técnicas de Cultura de Órgãos , Fosforilação/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Proteínas Proto-Oncogênicas c-akt/agonistas , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Somatostatina/deficiência , Transdução de Sinais , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/ultraestrutura
12.
Cell Tissue Res ; 358(3): 717-27, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25149275

RESUMO

Somatostatin (SST) is a peptide hormone that exerts inhibitory effects mediated through binding to specific cell surface G protein-coupled receptors, of which five distinct subtypes (SSTR1-SSTR5) have been characterized. Our study performed on mouse cochlear hair cells shows the expression and localization of the three receptors (SSTR3-SSTR5) in wild-type (WT), single-knockout (SSTR1 KO) and double-knockout SSTR1/SSTR2 (DKO) mice. Similar SSTRs expression were observed in the inner hair cells (IHC), outer hair cells (OHC) and supporting cells of cultivated P7 mouse organ of Corti (OC) explants as well as in cultivated cochlear neuroepithelial supporting cells (NEsc). We found differences in the expression of SSTR3-5 in WT, SSTR1 KO and DKO mouse cochlea, which might be explained as a compensatory effect in the cochlea after the loss of SSTR1 and/or SSTR2.


Assuntos
Cóclea/metabolismo , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/metabolismo , Envelhecimento/metabolismo , Animais , Cóclea/embriologia , Embrião de Mamíferos/metabolismo , Imunofluorescência , Regulação da Expressão Gênica no Desenvolvimento , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células Neuroepiteliais/metabolismo , Órgão Espiral/metabolismo , Receptores de Somatostatina/genética
13.
PLoS One ; 9(7): e100469, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25010045

RESUMO

Somatostatin receptor subtype 2 (SSTR2) is the most frequently expressed SSTR subtype in normal human tissues. SSTR2 expression is differentially regulated in various tumor types and therapeutic somatostatin analogs binding to SSTR2 are in clinical use. In prostate cancers highly contradictory results in terms of SSTR2 expression and its consequences have been published over the past years. The aim of this study was to clarify prevalence and clinical significance of SSTR2 expression in prostate cancer. Therefore, quantitative immunohistochemistry (IHC) using a tissue microarray containing samples from 3,261 prostate cancer patients with extensive clinical and molecular cancer characteristics and oncological follow-up data was performed. IHC data was compared to publicly available Gene Expression Omnibus datasets of human prostate cancer gene expression arrays. While membranous SSTR2 staining was always seen in normal prostate epithelium, SSTR2 staining was absent in more than half (56.1%) of 2,195 interpretable prostate cancer samples. About 13% of all analyzed prostate cancers showed moderate to strong cytoplasmic and membranous SSTR2 staining. Staining intensities were inversely correlated with high Gleason grade, advanced pT category, high tumor cell proliferation (p<0.0001 each), high pre-operative PSA levels, (p = 0.0011) and positive surgical margins (p = 0.006). In silico analysis confirmed lower SSTR2 gene expression in prostate cancers vs. normal adjacent tissue (p = 0.0424), prostate cancer metastases vs. primary cancers (p = 0.0011) and recurrent vs. non-recurrent prostate cancers (p = 0.0438). PSA-free survival gradually declined with SSTR2 staining intensity (p<0.0001). SSTR2-negative cancers were more likely to develop metastases over time (p<0.05). In conclusion, most prostate cancers are indeed SSTR2-negative and loss of SSTR2 strongly predicts an unfavorable tumor phenotype and poor prognosis. Therefore, SSTR2 expression seems an important factor in the pathogenesis of prostate cancer and re-introduction of the receptor in SSTR2-negative prostate cancers may feature a promising target for novel gene therapy approaches.


Assuntos
Fenótipo , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Receptores de Somatostatina/deficiência , Idoso , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Análise de Sequência com Séries de Oligonucleotídeos , Prognóstico , Neoplasias da Próstata/diagnóstico , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Recidiva
14.
Mol Pain ; 10: 12, 2014 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-24521084

RESUMO

BACKGROUND: Somatostatin (SST) and some of its receptor subtypes have been implicated in pain signaling at the spinal level. In this study we have investigated the role of SST and its sst2A receptor (sst2A) in dorsal root ganglia (DRGs) and spinal cord. RESULTS: SST and sst2A protein and sst2 transcript were found in both mouse and human DRGs, sst2A-immunoreactive (IR) cell bodies and processes in lamina II in mouse and human spinal dorsal horn, and sst2A-IR nerve terminals in mouse skin. The receptor protein was associated with the cell membrane. Following peripheral nerve injury sst2A-like immunoreactivity (LI) was decreased, and SST-LI increased in DRGs. sst2A-LI accumulated on the proximal and, more strongly, on the distal side of a sciatic nerve ligation. Fluorescence-labeled SST administered to a hind paw was internalized and retrogradely transported, indicating that a SST-sst2A complex may represent a retrograde signal. Internalization of sst2A was seen in DRG neurons after systemic treatment with the sst2 agonist octreotide (Oct), and in dorsal horn and DRG neurons after intrathecal administration. Some DRG neurons co-expressed sst2A and the neuropeptide Y Y1 receptor on the cell membrane, and systemic Oct caused co-internalization, hypothetically a sign of receptor heterodimerization. Oct treatment attenuated the reduction of pain threshold in a neuropathic pain model, in parallel suppressing the activation of p38 MAPK in the DRGs CONCLUSIONS: The findings highlight a significant and complex role of the SST system in pain signaling. The fact that the sst2A system is found also in human DRGs and spinal cord, suggests that sst2A may represent a potential pharmacologic target for treatment of neuropathic pain.


Assuntos
Gânglios Espinais/patologia , Receptores de Somatostatina/metabolismo , Ciática/metabolismo , Ciática/patologia , Células Receptoras Sensoriais/metabolismo , Somatostatina/metabolismo , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Lateralidade Funcional/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Glutamato Descarboxilase/genética , Proteínas de Fluorescência Verde/deficiência , Proteínas de Fluorescência Verde/genética , Humanos , Hiperalgesia/tratamento farmacológico , Hiperalgesia/etiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pessoa de Meia-Idade , Octreotida/uso terapêutico , Oligopeptídeos/farmacologia , Limiar da Dor/efeitos dos fármacos , Limiar da Dor/fisiologia , Transporte Proteico/efeitos dos fármacos , Transporte Proteico/genética , Receptores de Somatostatina/antagonistas & inibidores , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/genética , Ciática/complicações , Ciática/tratamento farmacológico , Células Receptoras Sensoriais/efeitos dos fármacos , Somatostatina/genética
15.
Nat Neurosci ; 16(7): 845-7, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23708141
16.
Dev Neurosci ; 34(4): 342-53, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22986312

RESUMO

The neuropeptide somatostatin (SST) exerts several important physiological actions in the adult central nervous system through interactions with membrane-bound receptors. Transient expression of SST and its receptors has been described in several brain areas during early ontogeny. It is therefore believed that SST may play a role in neural maturation. The present study provides the first evidence for the developmental expression of SST receptors in the mammalian cochlea, emphasizing their possible roles in cochlear maturation. In the developing mouse cochlea, cells immunoreactive to somatostatin receptor 1 (SSTR1) and somatostatin receptor 2 (SSTR2) were located in the embryonic cochlear duct on Kolliker's organ as early as embryonic day (E) 14 (E14). At E17, the expression of both receptors was high and already located at the hair cells and supporting cells along the length of the cochlear duct, which have become arranged into the characteristic pattern for the organ of Corti (OC) at this stage. At birth, SSTR1- and SSTR2-containing cells were only localized in the OC. In general, immunoreactivity for both receptors increased in the mouse cochlea from postnatal day (P) 0 (P0) to P10; the majority of immunostained cells were inner hair cells, outer hair cells, and supporting cells. Finally, a peak in the mRNA and protein expression of both receptors is present near the time when they respond to physiological hearing (i.e., hearing of airborne sound) at P14. At P21, SSTR1 and SSTR2 levels decrease dramatically. A similar developmental pattern was observed for SSTR1 and SSTR2 mRNA, suggesting that the expression of the SSTR1 and SSTR2 genes is controlled at the transcriptional level throughout development. In addition, we observed reduced levels of phospho-Akt and total Akt in SSTR1 knockout and SSTR1/SSTR2 double-knockout mice compared with wild-type mice. We know from previous studies that Akt is involved in hair cell survival. Taken together, the dynamic nature of SSTR1 and SSTR2 expression at a time of major developmental changes in the cochlea suggests that SSTR1 and SSTR2 (and possibly other members of this family) are involved in the maturation of the mammalian cochlea.


Assuntos
Cóclea/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas do Tecido Nervoso/biossíntese , Receptores de Somatostatina/biossíntese , Animais , Cóclea/embriologia , Cóclea/crescimento & desenvolvimento , Ducto Coclear/citologia , Ducto Coclear/embriologia , Ducto Coclear/crescimento & desenvolvimento , Ducto Coclear/metabolismo , Células Epiteliais/metabolismo , Feminino , Idade Gestacional , Células Ciliadas Auditivas/metabolismo , Audição/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Órgão Espiral/citologia , Órgão Espiral/embriologia , Órgão Espiral/crescimento & desenvolvimento , Órgão Espiral/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/genética , Transcrição Gênica
17.
J Neurochem ; 120(5): 818-29, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22168912

RESUMO

In a retinal ischemic ex vivo model, we have reported protective effects of somatostatin (SRIF) receptor 2 (sst(2) ). As an ischemic condition not only causes cell death but also induces a vascular response, we asked whether vascular endothelial growth factor (VEGF) is altered in this model and whether its expression, release or localization are affected by sst(2) activation. Ex vivo retinas of wild-type (WT) and sst(1) KO mice (which over-express sst(2) ) were incubated in ischemic conditions with SRIF, octreotide (OCT) or a VEGF trap. Ischemia in WT retinas caused increase of VEGF release and decrease of VEGF mRNA. Both effects were counteracted by SRIF or OCT. VEGF immunoreactivity was in retinal neurons and scarcely in vessels. Ischemia caused a significant shift of VEGF immunoreactivity from neurons to vessels. The increase of vascular VEGF was reduced in sst(1) KO retinas and in WT retinas treated with SRIF or OCT. VEGF trap also limited this increase, demonstrating that vascular VEGF was of extracellular origin. Together, the data show a VEGF response to ischemia, in which VEGF released by damaged neurons reaches the retinal capillaries. The activation of sst(2) protects neurons from ischemic damage, thereby limiting VEGF release and the VEGF response.


Assuntos
Isquemia/patologia , Retina/metabolismo , Somatostatina/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Proteínas do Olho/metabolismo , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas do Tecido Nervoso/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Octreotida/efeitos adversos , RNA Mensageiro , Receptores de Somatostatina/deficiência , Retina/patologia , Vasos Retinianos/metabolismo , Somatostatina/farmacologia , Fator A de Crescimento do Endotélio Vascular/genética
18.
PLoS One ; 6(9): e24467, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21912697

RESUMO

BACKGROUND: Selective degeneration of medium spiny neurons and preservation of medium sized aspiny interneurons in striatum has been implicated in excitotoxicity and pathophysiology of Huntington's disease (HD). However, the molecular mechanism for the selective sparing of medium sized aspiny neurons and vulnerability of projection neurons is still elusive. The pathological characteristic of HD is an extensive reduction of the striatal mass, affecting caudate putamen. Somatostatin (SST) positive neurons are selectively spared in HD and Quinolinic acid/N-methyl-D-aspartic acid induced excitotoxicity, mimic the model of HD. SST plays neuroprotective role in excitotoxicity and the biological effects of SST are mediated by five somatostatin receptor subtypes (SSTR1-5). METHODS AND FINDINGS: To delineate subtype selective biological responses we have here investigated changes in SSTR1 and 5 double knockout mice brain and compared with HD transgenic mouse model (R6/2). Our study revealed significant loss of dopamine and cAMP regulated phosphoprotein of 32 kDa (DARPP-32) and comparable changes in SST, N-methyl-D-aspartic acid receptors subtypes, calbindin and brain nitric oxide synthase expression as well as in key signaling proteins including calpain, phospho-extracellular-signal-regulated kinases1/2, synapsin-IIa, protein kinase C-α and calcineurin in SSTR1/5(-/-) and R6/2 mice. Conversely, the expression of somatostatin receptor subtypes, enkephalin and phosphatidylinositol 3-kinases were strain specific. SSTR1/5 appears to be important in regulating NMDARs, DARPP-32 and signaling molecules in similar fashion as seen in HD transgenic mice. CONCLUSIONS: This is the first comprehensive description of disease related changes upon ablation of G- protein coupled receptor gene. Our results indicate that SST and SSTRs might play an important role in regulation of neurodegeneration and targeting this pathway can provide a novel insight in understanding the pathophysiology of Huntington's disease.


Assuntos
Encéfalo/metabolismo , Técnicas de Inativação de Genes , Doença de Huntington/metabolismo , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/genética , Animais , Encéfalo/patologia , Calbindinas , Modelos Animais de Doenças , Fosfoproteína 32 Regulada por cAMP e Dopamina/metabolismo , Regulação da Expressão Gênica , Doença de Huntington/genética , Doença de Huntington/patologia , Masculino , Camundongos , Camundongos Transgênicos , Neostriado/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Óxido Nítrico Sintase Tipo I/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Proteína G de Ligação ao Cálcio S100/metabolismo , Transdução de Sinais/genética
19.
Neurosci Lett ; 484(2): 104-7, 2010 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-20709149

RESUMO

The Melanin Concentrating Hormone (MCH) system is widely expressed throughout the central nervous system and regulates a variety of physiological functions. It has been reported that acute central administration of MCH inhibits pentylenetetrazol (PTZ)-induced seizures in rats. In the present study MCH(1) receptor knockout mice (MCH(1)R-KO) were used to investigate the role of MCH signaling in modulating seizure susceptibility. Seizure behaviors were compared between MCH(1)R-KO and wild type (MCH(1)R-WT) mice following administration of the convulsant compounds PTZ or pilocarpine. PTZ injection induced clonic seizures in MCH(1)R-WT mice but failed to induce them in MCH(1)R-KO mice. More than twice as many injections of intermittently administered low dose PTZ were required to induce clonic seizures in MCH(1)R-KO mice than in MCH(1)R-WT mice. Following pilocarpine injection, MCH(1)R-WT mice experienced clonic seizures and most had tonic seizures and entered status epilepticus, while all MCH(1)R-KO mice were completely resistant to these effects. MCH(1)R-KO mice were also observed to be strongly protected from the development of PTZ kindling. Genetic deletion of MCH(1)R conferred resistance to all seizure models tested in this study. The data indicate that the MCH system is involved in the regulation of PTZ and pilocarpine seizure threshold.


Assuntos
Receptores de Somatostatina/deficiência , Convulsões/genética , Animais , Modelos Animais de Doenças , Estimativa de Kaplan-Meier , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , N-Metilescopolamina , Pentilenotetrazol , Pilocarpina , Receptores de Somatostatina/genética , Convulsões/induzido quimicamente , Convulsões/mortalidade , Convulsões/patologia
20.
J Neurophysiol ; 104(3): 1417-25, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20592115

RESUMO

The hypothalamic neuropeptide melanin-concentrating hormone (MCH) plays important roles in energy homeostasis, anxiety, and sleep regulation. Since the MCH receptor-1 (MCH-R1), the only functional receptor that mediates MCH functions in rodents, facilitates behavioral performance in hippocampus-dependent learning tasks, we investigated whether glutamatergic transmission in CA1 pyramidal cells could be modulated in mice lacking the MCH-R1 gene (MCH-R1(-/-)). We found that both α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) receptor-mediated transmissions were diminished in the mutant mice compared with their controls. This deficit was explained, at least in part, by a postsynaptic down-regulation of these receptors since the amplitude of miniature excitatory postsynaptic currents and the NMDA/AMPA ratio were decreased. Long-term synaptic potentiation (LTP) was also impaired in MCH-R1(-/-) mice. This was due to an altered induction, rather than an impaired, expression because repeating the induction stimulus restored LTP to a normal magnitude. In addition, long-term synaptic depression was strongly diminished in MCH-R1(-/-) mice. These results suggest that MCH exerts a facilitatory effect on CA1 glutamatergic synaptic transmission and long-term synaptic plasticity. Recently, it has been shown that MCH neurons fire exclusively during sleep and mainly during rapid eye movement sleep. Thus these findings provide a mechanism by which sleep might facilitate memory consolidation.


Assuntos
Ácido Glutâmico/fisiologia , Hipocampo/fisiologia , Plasticidade Neuronal/fisiologia , Receptores de Somatostatina/fisiologia , Sinapses/fisiologia , Transmissão Sináptica/fisiologia , Animais , Potenciais Pós-Sinápticos Excitadores/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Somatostatina/deficiência , Fatores de Tempo
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