RESUMO
Thermogenic adipocytes possess a therapeutically appealing, energy-expending capacity, which is canonically cold-induced by ligand-dependent activation of ß-adrenergic G protein-coupled receptors (GPCRs). Here, we uncover an alternate paradigm of GPCR-mediated adipose thermogenesis through the constitutively active receptor, GPR3. We show that the N terminus of GPR3 confers intrinsic signaling activity, resulting in continuous Gs-coupling and cAMP production without an exogenous ligand. Thus, transcriptional induction of Gpr3 represents the regulatory parallel to ligand-binding of conventional GPCRs. Consequently, increasing Gpr3 expression in thermogenic adipocytes is alone sufficient to drive energy expenditure and counteract metabolic disease in mice. Gpr3 transcription is cold-stimulated by a lipolytic signal, and dietary fat potentiates GPR3-dependent thermogenesis to amplify the response to caloric excess. Moreover, we find GPR3 to be an essential, adrenergic-independent regulator of human brown adipocytes. Taken together, our findings reveal a noncanonical mechanism of GPCR control and thermogenic activation through the lipolysis-induced expression of constitutively active GPR3.
Assuntos
Tecido Adiposo Marrom/metabolismo , Receptor Constitutivo de Androstano/metabolismo , Lipólise , Receptores Acoplados a Proteínas G/metabolismo , Termogênese , Adipócitos/metabolismo , Animais , Células COS , Células Cultivadas , Chlorocebus aethiops , Temperatura Baixa , Gorduras na Dieta/farmacologia , Humanos , Camundongos Endogâmicos C57BL , Fenótipo , Receptores Acoplados a Proteínas G/genética , Transdução de Sinais , Sistema Nervoso Simpático/metabolismo , Transcrição GênicaRESUMO
In this issue of Immunity, Bi et al. identify a microglia-neuron signaling axis that is critical for maintaining central control of the sympathetic nervous system. They find that platelet growth factor B released by microglia acts on neurons via PDGFRα to regulate sympathetic outflow. Disrupting this pathway leads to neuronal excitability, highlighting a promising therapeutic target to modulate sympathetic outflow and reduce hypertension.
Assuntos
Hipertensão , Sistema Nervoso Simpático , Humanos , Hipertensão/metabolismo , Neurônios/fisiologia , Sistema Nervoso Simpático/metabolismoRESUMO
Leptin is a hormone produced by the adipose tissue that acts in the brain, stimulating white fat breakdown. We find that the lipolytic effect of leptin is mediated through the action of sympathetic nerve fibers that innervate the adipose tissue. Using intravital two-photon microscopy, we observe that sympathetic nerve fibers establish neuro-adipose junctions, directly "enveloping" adipocytes. Local optogenetic stimulation of sympathetic inputs induces a local lipolytic response and depletion of white adipose mass. Conversely, genetic ablation of sympathetic inputs onto fat pads blocks leptin-stimulated phosphorylation of hormone-sensitive lipase and consequent lipolysis, as do knockouts of dopamine ß-hydroxylase, an enzyme required for catecholamine synthesis. Thus, neuro-adipose junctions are necessary and sufficient for the induction of lipolysis in white adipose tissue and are an efferent effector of leptin action. Direct activation of sympathetic inputs to adipose tissues may represent an alternative approach to induce fat loss, circumventing central leptin resistance. PAPERCLIP.
Assuntos
Tecido Adiposo Branco/metabolismo , Leptina/metabolismo , Lipólise , Tecido Adiposo Branco/inervação , Animais , Humanos , Camundongos , Fosforilação , Receptores Adrenérgicos beta/metabolismo , Sistema Nervoso Simpático/metabolismoRESUMO
Tissue macrophages provide immunological defense and contribute to the establishment and maintenance of tissue homeostasis. Here we used constitutive and inducible mutagenesis to delete the nuclear transcription regulator Mecp2 in macrophages. Mice that lacked the gene encoding Mecp2, which is associated with Rett syndrome, in macrophages did not show signs of neurodevelopmental disorder but displayed spontaneous obesity, which was linked to impaired function of brown adipose tissue (BAT). Specifically, mutagenesis of a BAT-resident Cx3Cr1+ macrophage subpopulation compromised homeostatic thermogenesis but not acute, cold-induced thermogenesis. Mechanistically, malfunction of BAT in pre-obese mice with mutant macrophages was associated with diminished sympathetic innervation and local titers of norepinephrine, which resulted in lower expression of thermogenic factors by adipocytes. Mutant macrophages overexpressed the signaling receptor and ligand PlexinA4, which might contribute to the phenotype by repulsion of sympathetic axons expressing the transmembrane semaphorin Sema6A. Collectively, we report a previously unappreciated homeostatic role for macrophages in the control of tissue innervation. Disruption of this circuit in BAT resulted in metabolic imbalance.
Assuntos
Tecido Adiposo Marrom/imunologia , Macrófagos/imunologia , Proteína 2 de Ligação a Metil-CpG/genética , Sistema Nervoso Simpático/metabolismo , Termogênese/imunologia , Adipócitos Marrons , Tecido Adiposo Marrom/inervação , Tecido Adiposo Marrom/metabolismo , Animais , Axônios/metabolismo , Receptor 1 de Quimiocina CX3C , Metabolismo Energético/imunologia , Citometria de Fluxo , Homeostase , Immunoblotting , Macrófagos/metabolismo , Camundongos , Mutagênese Sítio-Dirigida , Proteínas do Tecido Nervoso/metabolismo , Norepinefrina/metabolismo , Obesidade/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Superfície Celular/metabolismo , Receptores de Quimiocinas/metabolismo , Semaforinas/metabolismoRESUMO
Melanocortin 4 receptors (MC4Rs) in the central nervous system are key regulators of energy and glucose homeostasis. Notably, obese patients with MC4R mutations are hyperinsulinemic and resistant to obesity-induced hypertension. Although these effects are probably dependent upon the activity of the autonomic nervous system, the cellular effects of MC4Rs on parasympathetic and sympathetic neurons remain undefined. Here, we show that MC4R agonists inhibit parasympathetic preganglionic neurons in the brainstem. In contrast, MC4R agonists activate sympathetic preganglionic neurons in the spinal cord. Deletion of MC4Rs in cholinergic neurons resulted in elevated levels of insulin. Furthermore, re-expression of MC4Rs specifically in cholinergic neurons (including sympathetic preganglionic neurons) restores obesity-associated hypertension in MC4R null mice. These findings provide a cellular correlate of the autonomic side effects associated with MC4R agonists and demonstrate a role for MC4Rs expressed in cholinergic neurons in the regulation of insulin levels and in the development of obesity-induced hypertension.
Assuntos
Tronco Encefálico/metabolismo , Insulina/metabolismo , Neurônios/metabolismo , Receptor Tipo 4 de Melanocortina/agonistas , Receptor Tipo 4 de Melanocortina/metabolismo , Animais , Pressão Sanguínea , Tronco Encefálico/citologia , Neurônios Colinérgicos/metabolismo , AMP Cíclico/metabolismo , Fenômenos Eletrofisiológicos , Humanos , Canais KATP/metabolismo , Masculino , Camundongos , Obesidade/metabolismo , Obesidade/fisiopatologia , Sistema Nervoso Parassimpático/metabolismo , Receptor Tipo 4 de Melanocortina/genética , Medula Espinal/metabolismo , Sistema Nervoso Simpático/metabolismoRESUMO
The molecular mechanisms that link the sympathetic stress response and inflammation remain obscure. Here we found that the transcription factor Nr4a1 regulated the production of norepinephrine (NE) in macrophages and thereby limited experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Lack of Nr4a1 in myeloid cells led to enhanced NE production, accelerated infiltration of leukocytes into the central nervous system (CNS) and disease exacerbation in vivo. In contrast, myeloid-specific deletion of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, protected mice against EAE. Furthermore, we found that Nr4a1 repressed autocrine NE production in macrophages by recruiting the corepressor CoREST to the Th promoter. Our data reveal a new role for macrophages in neuroinflammation and identify Nr4a1 as a key regulator of catecholamine production by macrophages.
Assuntos
Sistema Nervoso Central/imunologia , Encefalomielite Autoimune Experimental/imunologia , Inflamação/imunologia , Macrófagos/imunologia , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/imunologia , Sistema Nervoso Simpático/imunologia , Animais , Linhagem Celular , Células Cultivadas , Sistema Nervoso Central/metabolismo , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/metabolismo , Expressão Gênica/imunologia , Humanos , Inflamação/genética , Inflamação/metabolismo , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Esclerose Múltipla/imunologia , Esclerose Múltipla/patologia , Células Mieloides/imunologia , Células Mieloides/metabolismo , Norepinefrina/imunologia , Norepinefrina/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Coelhos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sistema Nervoso Simpático/metabolismo , Tirosina 3-Mono-Oxigenase/genética , Tirosina 3-Mono-Oxigenase/imunologia , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
There is a growing body of research on the neural control of immunity and inflammation. However, it is not known whether the nervous system can regulate the production of inflammatory myeloid cells from hematopoietic progenitor cells in disease conditions. Myeloid cell numbers in diabetic patients were strongly correlated with plasma concentrations of norepinephrine, suggesting the role of sympathetic neuronal activation in myeloid cell production. The spleens of diabetic patients and mice contained higher numbers of tyrosine hydroxylase (TH)-expressing leukocytes that produced catecholamines. Granulocyte macrophage progenitors (GMPs) expressed the ß2 adrenergic receptor, a target of catecholamines. Ablation of splenic sympathetic neuronal signaling using surgical, chemical, and genetic approaches diminished GMP proliferation and myeloid cell development. Finally, mice lacking TH-producing leukocytes had reduced GMP proliferation, resulting in diminished myelopoiesis. Taken together, our study demonstrates that catecholamines produced by leukocytes and sympathetic nerve termini promote GMP proliferation and myeloid cell development.
Assuntos
Diabetes Mellitus/fisiopatologia , Células Progenitoras de Granulócitos e Macrófagos/citologia , Células Progenitoras de Granulócitos e Macrófagos/metabolismo , Mielopoese , Neuroimunomodulação , Sistema Nervoso Simpático/metabolismo , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Diabetes Mellitus/sangue , Modelos Animais de Doenças , Feminino , Humanos , Leucócitos/enzimologia , Leucócitos/metabolismo , Masculino , Camundongos , Células Mieloides/citologia , Mielopoese/efeitos dos fármacos , Neuroimunomodulação/efeitos dos fármacos , Norepinefrina/sangue , Transdução de Sinais/efeitos dos fármacos , Baço/citologia , Baço/inervação , Baço/metabolismo , Sistema Nervoso Simpático/efeitos dos fármacosRESUMO
Signals from sympathetic neurons and immune cells regulate adipocytes and thereby contribute to fat tissue biology. Interactions between the nervous and immune systems have recently emerged as important regulators of host defence and inflammation1-4. Nevertheless, it is unclear whether neuronal and immune cells co-operate in brain-body axes to orchestrate metabolism and obesity. Here we describe a neuro-mesenchymal unit that controls group 2 innate lymphoid cells (ILC2s), adipose tissue physiology, metabolism and obesity via a brain-adipose circuit. We found that sympathetic nerve terminals act on neighbouring adipose mesenchymal cells via the ß2-adrenergic receptor to control the expression of glial-derived neurotrophic factor (GDNF) and the activity of ILC2s in gonadal fat. Accordingly, ILC2-autonomous manipulation of the GDNF receptor machinery led to alterations in ILC2 function, energy expenditure, insulin resistance and propensity to obesity. Retrograde tracing and chemical, surgical and chemogenetic manipulations identified a sympathetic aorticorenal circuit that modulates ILC2s in gonadal fat and connects to higher-order brain areas, including the paraventricular nucleus of the hypothalamus. Our results identify a neuro-mesenchymal unit that translates cues from long-range neuronal circuitry into adipose-resident ILC2 function, thereby shaping host metabolism and obesity.
Assuntos
Tecido Adiposo/inervação , Tecido Adiposo/metabolismo , Encéfalo/metabolismo , Imunidade Inata/imunologia , Mesoderma/citologia , Vias Neurais , Neurônios/citologia , Obesidade/metabolismo , Tecido Adiposo/citologia , Animais , Encéfalo/citologia , Sinais (Psicologia) , Citocinas/metabolismo , Metabolismo Energético , Feminino , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Gônadas/metabolismo , Mesoderma/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Proteínas Proto-Oncogênicas c-ret/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Sistema Nervoso Simpático/citologia , Sistema Nervoso Simpático/metabolismoRESUMO
Obesity is increasingly prevalent and is associated with substantial cardiovascular risk. Adipose tissue distribution and morphology play a key role in determining the degree of adverse effects, and a key factor in the disease process appears to be the inflammatory cell population in adipose tissue. Healthy adipose tissue secretes a number of vasoactive adipokines and anti-inflammatory cytokines, and changes to this secretory profile will contribute to pathogenesis in obesity. In this review, we discuss the links between adipokine dysregulation and the development of hypertension and diabetes and explore the potential for manipulating adipose tissue morphology and its immune cell population to improve cardiovascular health in obesity.
Assuntos
Tecido Adiposo/fisiopatologia , Pressão Sanguínea , Diabetes Mellitus/fisiopatologia , Hipertensão/fisiopatologia , Obesidade/fisiopatologia , Adipocinas/metabolismo , Tecido Adiposo/imunologia , Tecido Adiposo/metabolismo , Adiposidade , Animais , Diabetes Mellitus/epidemiologia , Diabetes Mellitus/imunologia , Diabetes Mellitus/metabolismo , Humanos , Hipertensão/epidemiologia , Hipertensão/imunologia , Hipertensão/metabolismo , Mediadores da Inflamação/metabolismo , Obesidade/epidemiologia , Obesidade/imunologia , Obesidade/metabolismo , Fenótipo , Medição de Risco , Fatores de Risco , Transdução de Sinais , Sistema Nervoso Simpático/metabolismo , Sistema Nervoso Simpático/fisiopatologiaRESUMO
In neurons, many membrane proteins, synthesized in cell bodies, must be efficiently delivered to axons to influence neuronal connectivity, synaptic communication, and repair. Previously, we found that axonal targeting of TrkA neurotrophin receptors in sympathetic neurons occurs via an atypical transport mechanism called transcytosis, which relies on TrkA interactions with PTP1B, a protein tyrosine phosphatase. Here, we generated TrkAR685A mice, where TrkA receptor signaling is preserved, but its PTP1B-dependent transcytosis is disrupted to show that this mode of axonal transport is essential for sympathetic neuron development and autonomic function. TrkAR685A mice have decreased axonal TrkA levels in vivo, loss of sympathetic neurons, and reduced innervation of targets. The neuron loss and diminished target innervation phenotypes are specifically restricted to the developmental period when sympathetic neurons are known to rely on the TrkA ligand, nerve growth factor, for trophic support. Postnatal TrkAR685A mice exhibit reduced pupil size and eyelid ptosis, indicative of sympathetic dysfunction. Furthermore, we also observed a significant loss of TrkA-expressing nociceptive neurons in the dorsal root ganglia during development in TrkAR685A mice, suggesting that transcytosis might be a general mechanism for axonal targeting of TrkA receptors. Together, these findings establish the necessity of transcytosis in supplying TrkA receptors to axons, specifically during development, and highlight the physiological relevance of this axon targeting mechanism in the nervous system.
Assuntos
Neurônios , Receptor trkA , Camundongos , Animais , Receptor trkA/genética , Receptor trkA/metabolismo , Neurônios/metabolismo , Receptores de Fator de Crescimento Neural/genética , Axônios/metabolismo , Transcitose , Sistema Nervoso Simpático/metabolismoRESUMO
Increased expression of angiotensin II AT1A receptor (encoded by Agtr1a) and Na+-K+-Cl- cotransporter-1 (NKCC1, encoded by Slc12a2) in the hypothalamic paraventricular nucleus (PVN) contributes to hypertension development. However, little is known about their transcriptional control in the PVN in hypertension. DNA methylation is a critical epigenetic mechanism that regulates gene expression. Here, we determined whether transcriptional activation of Agtr1a and Slc12a2 results from altered DNA methylation in spontaneously hypertensive rats (SHR). Methylated DNA immunoprecipitation and bisulfite sequencing-PCR showed that CpG methylation at Agtr1a and Slc12a2 promoters in the PVN was progressively diminished in SHR compared with normotensive Wistar-Kyoto rats (WKY). Chromatin immunoprecipitation-quantitative PCR revealed that enrichment of DNA methyltransferases (DNMT1 and DNMT3A) and methyl-CpG binding protein 2, a DNA methylation reader protein, at Agtr1a and Slc12a2 promoters in the PVN was profoundly reduced in SHR compared with WKY. By contrast, the abundance of ten-eleven translocation enzymes (TET1-3) at Agtr1a and Slc12a2 promoters in the PVN was much greater in SHR than in WKY. Furthermore, microinjecting of RG108, a selective DNMT inhibitor, into the PVN of WKY increased arterial blood pressure and correspondingly potentiated Agtr1a and Slc12a2 mRNA levels in the PVN. Conversely, microinjection of C35, a specific TET inhibitor, into the PVN of SHR markedly reduced arterial blood pressure, accompanied by a decrease in Agtr1a and Slc12a2 mRNA levels in the PVN. Collectively, our findings suggest that DNA hypomethylation resulting from the DNMT/TET switch at gene promoters in the PVN promotes transcription of Agtr1a and Slc12a2 and hypertension development.
Assuntos
Desmetilação do DNA , Hipotálamo , Receptor Tipo 1 de Angiotensina , Membro 2 da Família 12 de Carreador de Soluto , Animais , Ratos , Pressão Sanguínea , DNA/metabolismo , Hipertensão/metabolismo , Hipotálamo/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Receptor Tipo 1 de Angiotensina/metabolismo , RNA Mensageiro/genética , Sistema Nervoso Simpático/metabolismo , Membro 2 da Família 12 de Carreador de Soluto/metabolismoRESUMO
A functional nerve growth factor NGF-Tropomyosin Receptor kinase A (TrkA) system is an essential requisite for the generation and maintenance of long-lasting thermal and mechanical hyperalgesia in adult mammals. Indeed, mutations in the gene encoding for TrkA are responsible for a rare condition, named Hereditary Sensory and Autonomic Neuropathy type IV (HSAN IV), characterized by the loss of response to noxious stimuli, anhidrosis and cognitive impairment. However, to date, there is no available mouse model to properly understand how the NGF-TrkA system can lead to pathological phenotypes that are distinctive of HSAN IV. Here, we report the generation of a knock-in mouse line carrying the HSAN IV TrkAR649W mutation. First, by in vitro biochemical and biophysical analyses, we show that the pathological R649W mutation leads to kinase-inactive TrkA also affecting its membrane dynamics and trafficking. In agreement with the HSAN IV human phenotype, TrkAR649W/m mice display a lower response to thermal and chemical noxious stimuli, correlating with reduced skin innervation, in addition to decreased sweating in comparison to TrkAh/m controls. Moreover, the R649W mutation decreases anxiety-like behavior and compromises cognitive abilities, by impairing spatial-working and social memory. Our results further uncover unexplored roles of TrkA in thermoregulation and sociability. In addition to accurately recapitulating the clinical manifestations of HSAN IV patients, our findings contribute to clarifying the involvement of the NGF-TrkA system in pain sensation.
Assuntos
Modelos Animais de Doenças , Neuropatias Hereditárias Sensoriais e Autônomas , Receptor trkA , Humanos , Animais , Camundongos , Mutação , Receptor trkA/genética , Técnicas de Introdução de Genes , Fator de Crescimento Neural/metabolismo , Fosforilação , Genes Letais , Dor/metabolismo , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Pele/metabolismo , Pele/patologia , Sistema Nervoso Simpático/metabolismo , Hipo-Hidrose/metabolismo , Comportamento AnimalRESUMO
The sympathetic nervous system drives brown and beige adipocyte thermogenesis through the release of noradrenaline from local axons. However, the molecular basis of higher levels of sympathetic innervation of thermogenic fat, compared to white fat, has remained unknown. Here we show that thermogenic adipocytes express a previously unknown, mammal-specific protein of the endoplasmic reticulum that we term calsyntenin 3ß. Genetic loss or gain of expression of calsyntenin 3ß in adipocytes reduces or enhances functional sympathetic innervation, respectively, in adipose tissue. Ablation of calsyntenin 3ß predisposes mice on a high-fat diet to obesity. Mechanistically, calsyntenin 3ß promotes endoplasmic-reticulum localization and secretion of S100b-a protein that lacks a signal peptide-from brown adipocytes. S100b stimulates neurite outgrowth from sympathetic neurons in vitro. A deficiency of S100b phenocopies deficiency of calsyntenin 3ß, and forced expression of S100b in brown adipocytes rescues the defective sympathetic innervation that is caused by ablation of calsyntenin 3ß. Our data reveal a mammal-specific mechanism of communication between thermogenic adipocytes and sympathetic neurons.
Assuntos
Tecido Adiposo Marrom/inervação , Tecido Adiposo Marrom/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Membrana/metabolismo , Neurônios/metabolismo , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Sistema Nervoso Simpático/citologia , Termogênese , Adipócitos/metabolismo , Animais , Proteínas de Ligação ao Cálcio/deficiência , Proteínas de Ligação ao Cálcio/genética , Dieta Hiperlipídica , Retículo Endoplasmático/metabolismo , Feminino , Masculino , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Transgênicos , Neuritos/metabolismo , Obesidade/metabolismo , Especificidade de Órgãos , Sistema Nervoso Simpático/metabolismo , Termogênese/genéticaRESUMO
Neural regulation of hepatic metabolism has long been recognized. However, the detailed afferent and efferent innervation of the human liver has not been systematically characterized. This is largely due to the liver's high lipid and pigment contents, causing false-negative (light scattering and absorption) and false-positive (autofluorescence) results in in-depth fluorescence imaging. Here, to avoid the artifacts in three-dimensional (3-D) liver neurohistology, we embed the bleached human liver in the high-refractive-index polymer for tissue clearing and antifade 3-D/Airyscan super-resolution imaging. Importantly, using the paired substance P (SP, sensory marker) and PGP9.5 (pan-neuronal marker) labeling, we detect the sensory nerves in the portal space, featuring the SP+ varicosities in the PGP9.5+ nerve bundles/fibers, confirming the afferent liver innervation. Also, using the tyrosine hydroxylase (TH, sympathetic marker) labeling, we identify 1) condensed TH+ sympathetic nerves in the portal space, 2) extension of sympathetic nerves from the portal to the intralobular space, in which the TH+ nerve density is 2.6 ± 0.7-fold higher than that of the intralobular space in the human pancreas, and 3) the TH+ nerve fibers and varicosities contacting the ballooning cells, implicating potential sympathetic influence on hepatocytes with macrovesicular fatty change. Finally, using the vesicular acetylcholine transporter (VAChT, parasympathetic marker), PGP9.5, and CK19 (epithelial marker) labeling with panoramic-to-Airyscan super-resolution imaging, we detect and confirm the parasympathetic innervation of the septal bile duct. Overall, our labeling and 3-D/Airyscan imaging approach reveal the hepatic sensory (afferent) and sympathetic and parasympathetic (efferent) innervation, establishing a clinically related setting for high-resolution 3-D liver neurohistology.NEW & NOTEWORTHY We embed the human liver (vs. pancreas, positive control) in the high-refractive-index polymer for tissue clearing and antifade 3-D/Airyscan super-resolution neurohistology. The pancreas-liver comparison reveals: 1) sensory nerves in the hepatoportal space; 2) intralobular sympathetic innervation, including the nerve fibers and varicosities contacting the ballooning hepatocytes; and 3) parasympathetic innervation of the septal bile duct. Our results highlight the sensitivity and resolving power of 3-D/Airyscan super-resolution imaging in human liver neurohistology.
Assuntos
Fígado , Neurônios , Humanos , Fígado/metabolismo , Neurônios/metabolismo , Sistema Nervoso Simpático/metabolismo , Polímeros , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Sympathetic hyperinnervation is the leading cause of fatal ventricular arrhythmia (VA) after myocardial infarction (MI). Cardiac mast cells cause arrhythmias directly through degranulation. However, the role and mechanism of mast cell degranulation in sympathetic remodeling remain unknown. We investigated the role of oxytocin (OT) in stabilizing cardiac mast cells and improving sympathetic innervation in rats. MI was induced by coronary artery ligation. Western blotting, immunofluorescence, and toluidine staining of mast cells were performed to determine the expression and location of target protein. Mast cells accumulated significantly in peri-infarcted tissues and were present in a degranulated state. They expressed OT receptor (OTR), and OT infusion reduced the number of degranulated cardiac mast cells post-MI. Sympathetic hyperinnervation was attenuated as assessed by immunofluorescence for tyrosine hydroxylase (TH). Seven days post-MI, the arrhythmia score of programmed electrical stimulation was higher in vehicle-treated rats with MI than in rats treated with OT. An in vitro study showed that OT stabilized mast cells via the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. Further in vivo studies on OTR-deficient mice showed worsening mast cell degranulation and worsening sympathetic innervation. OT pretreatment inhibited cardiac mast cell degranulation post-MI and prevented sympathetic hyperinnervation, along with mast cell stabilization via the PI3K/Akt pathway. SIGNIFICANCE STATEMENT: This is the first study to elucidate the role and mechanism of oxytocin (OT) in inflammatory-sympathetic communication mediated sympathetic hyperinnervation after myocardial infarction (MI), providing new approaches to prevent fatal arrhythmias.
Assuntos
Degranulação Celular , Mastócitos , Infarto do Miocárdio , Ocitocina , Ratos Sprague-Dawley , Receptores de Ocitocina , Sistema Nervoso Simpático , Animais , Ocitocina/farmacologia , Ocitocina/metabolismo , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/metabolismo , Mastócitos/efeitos dos fármacos , Mastócitos/metabolismo , Ratos , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/metabolismo , Masculino , Degranulação Celular/efeitos dos fármacos , Receptores de Ocitocina/metabolismo , Receptores de Ocitocina/antagonistas & inibidores , Camundongos , Transdução de Sinais/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/tratamento farmacológico , Arritmias Cardíacas/etiologiaRESUMO
The sympathetic arm of the inflammatory reflex is the efferent pathway through which the central nervous system (CNS) can control peripheral immune responses. Diminazene aceturate (DIZE) is an antiparasitic drug that has been reported to exert protective effects on various experimental models of inflammation. However, the pathways by which DIZE promotes a protective immunomodulatory effects still need to be well established, and no studies demonstrate the capacity of DIZE to modulate a neural reflex to control inflammation. C57BL/6 male mice received intraperitoneal administration of DIZE (2 mg/Kg) followed by lipopolysaccharide (LPS, 5 mg/Kg, i.p.). Endotoxemic animals showed hyperresponsiveness to inflammatory signals, while those treated with DIZE promoted the activation of the inflammatory reflex to attenuate the inflammatory response during endotoxemia. The unilateral cervical vagotomy did not affect the anti-inflammatory effect of DIZE in the spleen and serum. At the same time, splenic denervation attenuated tumor necrosis factor (TNF) synthesis in the spleen and serum. Using broad-spectrum antibiotics for two weeks showed that LPS modulated the microbiota to induce a pro-inflammatory profile in the intestine and reduced the serum concentration of tryptophan and serotonin (5-HT), while DIZE restored serum tryptophan and increased the hypothalamic 5-HT levels. Furthermore, the treatment with 4-Chloro-DL-phenylalanine (pcpa, an inhibitor of 5-HT synthesis) abolished the anti-inflammatory effects of the DIZE in the spleen. Our results indicate that DIZE promotes microbiota modulation to increase central 5-HT levels and activates the efferent sympathetic arm of the inflammatory reflex to control splenic TNF production in endotoxemic mice.
Assuntos
Diminazena , Endotoxemia , Microbioma Gastrointestinal , Inflamação , Lipopolissacarídeos , Camundongos Endogâmicos C57BL , Serotonina , Baço , Sistema Nervoso Simpático , Animais , Masculino , Camundongos , Baço/metabolismo , Baço/efeitos dos fármacos , Diminazena/análogos & derivados , Diminazena/farmacologia , Lipopolissacarídeos/farmacologia , Microbioma Gastrointestinal/efeitos dos fármacos , Inflamação/metabolismo , Serotonina/metabolismo , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/metabolismo , Endotoxemia/metabolismo , Encéfalo/metabolismo , Encéfalo/efeitos dos fármacos , Eixo Encéfalo-Intestino/efeitos dos fármacos , Anti-Inflamatórios/farmacologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Hypertension is among the most harmful factors of cardiovascular and cerebrovascular diseases and poses an urgent problem for the development of human society. In addition to previous studies on its pathogenesis focusing on the peripheral sympathetic nervous system, investigating the central causes of high blood pressure involving the neuroendocrine and neuroinflammatory mechanisms of the hypothalamic paraventricular nucleus (PVN) is paramount. This nucleus is considered to regulate the output of neurohormones and sympathetic nerve activity. In this article, we focussed on the neuroendocrine mechanism, primarily exploring the specific contributions and interactions of various neurons and neuroendocrine hormones, including GABAergic and glutamatergic neurons, nitric oxide, arginine vasopressin, oxytocin, and the renin-angiotensin system. Additionally, the neuroinflammatory mechanism in the PVN was discussed, encompassing microglia, reactive oxygen species, inflammatory factors, and pathways, as well as immune connections between the brain and extracerebral organs. Notably, the two central mechanisms involved in the PVN not only exist independently but also communicate with each other, jointly maintaining the hypertensive state of the body. Furthermore, we introduce well-known molecules and signal transduction pathways within the PVN that can play a regulatory role in the two mechanisms to provide a basis and inspire ideas for further research.
Assuntos
Hipertensão , Núcleo Hipotalâmico Paraventricular , Humanos , Núcleo Hipotalâmico Paraventricular/metabolismo , Pressão Sanguínea/fisiologia , Hipertensão/metabolismo , Sistema Nervoso Simpático/metabolismo , Neurônios/fisiologiaRESUMO
ABSTRACT: Previous studies have found that anxiety disorders may increase the incidence of atrial fibrillation (AF). More and more studies have shown that α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are involved in the occurrence and development of cardiovascular diseases. However, the role of AMPARs in AF associated with anxiety disorder remains unclear. The aim of this study was to investigate the effect of AMPARs on AF susceptibility in rats with anxiety disorder and its possible mechanism. The anxiety disorder rat model was established by unpredictable empty bottle stimulation and was treated with AMPARs agonist and antagonist. Our results showed that AMPARs antagonist treatment significantly reduced sympathetic activity, improved heart rate variability, shortened action potential duration, prolonged effective refractory period, reduced AF induction rate, and improved cardiac electrical remodeling and the expression of inflammatory factors. In addition, inhibition of AMPARs reduced the phosphorylation of IκBα and p65. Our experimental results suggest that inhibition of AMPARs can reduce autonomic remodeling, improve atrial electrical remodeling, and suppress myocardial inflammation, which provides a potential therapeutic strategy for the treatment of AF associated with anxiety disorder.
Assuntos
Transtornos de Ansiedade , Fibrilação Atrial , Modelos Animais de Doenças , Átrios do Coração , Ratos Sprague-Dawley , Receptores de AMPA , Animais , Fibrilação Atrial/fisiopatologia , Fibrilação Atrial/tratamento farmacológico , Fibrilação Atrial/metabolismo , Masculino , Transtornos de Ansiedade/tratamento farmacológico , Transtornos de Ansiedade/metabolismo , Transtornos de Ansiedade/fisiopatologia , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/fisiopatologia , Átrios do Coração/metabolismo , Átrios do Coração/patologia , Receptores de AMPA/metabolismo , Remodelamento Atrial/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Mediadores da Inflamação/metabolismo , Potenciais de Ação/efeitos dos fármacos , Fosforilação , Transdução de Sinais , Sistema Nervoso Simpático/fisiopatologia , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/metabolismo , Fator de Transcrição RelA/metabolismo , Ratos , Anti-Inflamatórios/farmacologia , Período Refratário Eletrofisiológico/efeitos dos fármacos , Inibidor de NF-kappaB alfa/metabolismoRESUMO
PURPOSE OF REVIEW: Granulocyte colony-stimulating factor (G-CSF) is now a standard agent to mobilize hematopoietic stem cells (HSCs) from the bone marrow to circulation. This review introduced mechanistic insights from the aspect of the sympathetic nervous system (SNS). RECENT FINDINGS: Mobilization efficiency is determined by the balance between promotion and suppression pathways critically regulated by the SNS. G-CSF-induced high catecholaminergic tone promotes mobilization by (1) the strong suppression of osteolineage cells as a hematopoietic microenvironment and (2) fibroblast growth factor 23 production from erythroblasts, which inhibits CXCR4 function in HSCs. Simultaneously, SNS signals inhibit mobilization by (1) prostaglandin E2 production from mature neutrophils to induce osteopontin in osteoblasts to anchor HSCs and (2) angiopoietin-like protein 4 production from immature neutrophils via peroxisome proliferator-activated receptor δ to inhibit BM vascular permeability. SUMMARY: We now know not only the regulatory mechanisms of G-CSF-induced mobilization but also the leads about unfavorable clinical phenomena, such as low-grade fever, bone pain, and poor mobilizers. Recent understanding of the mechanism will assist clinicians in the treatment for mobilization and researchers in the studies of the hidden potential of BM.
Assuntos
Mobilização de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas , Humanos , Células-Tronco Hematopoéticas/metabolismo , Medula Óssea/metabolismo , Fator Estimulador de Colônias de Granulócitos/farmacologia , Sistema Nervoso Simpático/metabolismoRESUMO
Ubiquitin-specific protease 2 (USP2) participates in glucose metabolism in peripheral tissues such as the liver and skeletal muscles. However, the glucoregulatory role of USP2 in the CNS is not well known. In this study, we focus on USP2 in the ventromedial hypothalamus (VMH), which has dominant control over systemic glucose homeostasis. ISH, using a Usp2-specific probe, showed that Usp2 mRNA is present in VMH neurons, as well as other glucoregulatory nuclei, in the hypothalamus of male mice. Administration of a USP2-selective inhibitor ML364 (20 ng/head), into the VMH elicited a rapid increase in the circulating glucose level in male mice, suggesting USP2 has a suppressive role on glucose mobilization. ML364 treatment also increased serum norepinephrine concentration, whereas it negligibly affected serum levels of insulin and corticosterone. ML364 perturbated mitochondrial oxidative phosphorylation in neural SH-SY5Y cells and subsequently promoted the phosphorylation of AMP-activated protein kinase (AMPK). Consistent with these findings, hypothalamic ML364 treatment stimulated AMPKα phosphorylation in the VMH. Inhibition of hypothalamic AMPK prevented ML364 from increasing serum norepinephrine and blood glucose. Removal of ROS restored the ML364-evoked mitochondrial dysfunction in SH-SY5Y cells and impeded the ML364-induced hypothalamic AMPKα phosphorylation as well as prevented the elevation of serum norepinephrine and blood glucose levels in male mice. These results indicate hypothalamic USP2 attenuates perturbations in blood glucose levels by modifying the ROS-AMPK-sympathetic nerve axis.SIGNIFICANCE STATEMENT Under normal conditions (excluding hyperglycemia or hypoglycemia), blood glucose levels are maintained at a constant level. In this study, we used a mouse model to identify a hypothalamic protease controlling blood glucose levels. Pharmacological inhibition of USP2 in the VMH caused a deviation in blood glucose levels under a nonstressed condition, indicating that USP2 determines the set point of the blood glucose level. Modification of sympathetic nervous activity accounts for the USP2-mediated glucoregulation. Mechanistically, USP2 mitigates the accumulation of ROS in the VMH, resulting in attenuation of the phosphorylation of AMPK. Based on these findings, we uncovered a novel glucoregulatory axis consisting of hypothalamic USP2, ROS, AMPK, and the sympathetic nervous system.