RESUMEN
AIMS/HYPOTHESIS: Our aim was to investigate structural changes of cutaneous Schwann cells (SCs), including nociceptive Schwann cells (nSCs) and axons, in individuals with diabetic polyneuropathy. We also aimed to investigate the relationship between these changes and peripheral neuropathic symptoms in type 1 diabetes. METHODS: Skin biopsies (3 mm) taken from carefully phenotyped participants with type 1 diabetes without polyneuropathy (T1D, n=25), type 1 diabetes with painless diabetic polyneuropathy (T1DPN, n=30) and type 1 diabetes with painful diabetic polyneuropathy (P-T1DPN, n=27), and from healthy control individuals (n=25) were immunostained with relevant antibodies to visualise SCs and nerve fibres. Stereological methods were used to quantify the expression of cutaneous SCs and nerve fibres. RESULTS: There was a difference in the number density of nSCs not abutting to nerve fibres between the groups (p=0.004) but not in the number density of nSCs abutting to nerve fibres, nor in solitary or total subepidermal SC soma number density. The overall dermal SC expression (measured by dermal SC area fraction and subepidermal SC process density) and peripheral nerve fibre expression (measured by intraepidermal nerve fibre density, dermal nerve fibre area fraction and subepidermal nerve fibre density) differed between the groups (all p<0.05): significant differences were seen in participants with T1DPN and P-T1DPN compared with those without diabetic polyneuropathy (healthy control and T1D groups) (all p<0.05). No difference was found between participants in the T1DPN and P-T1DPN group, nor between participants in the T1D and healthy control group (all p>0.05). Correlational analysis showed that cutaneous SC processes and nerve fibres were highly associated, and they were weakly negatively correlated with different neuropathy measures. CONCLUSIONS/INTERPRETATION: Cutaneous SC processes and nerves, but not SC soma, are degenerated and interdependent in individuals with diabetic polyneuropathy. However, an increase in structurally damaged nSCs was seen in individuals with diabetic polyneuropathy. Furthermore, dermal SC processes and nerve fibres correlate weakly with clinical measures of neuropathy and may play a partial role in the pathophysiology of diabetic polyneuropathy in type 1 diabetes.
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Diabetes Mellitus Tipo 1 , Neuropatías Diabéticas , Humanos , Diabetes Mellitus Tipo 1/complicaciones , Fibras Nerviosas/patología , Nervios Periféricos/patología , Células de Schwann/patologíaRESUMEN
Touch and mechanical sensations require the development of several different kinds of sensory neurons dedicated to respond to certain types of mechanical stimuli. The transcription factor Shox2 (short stature homeobox 2) is involved in the generation of TRKB+ low-threshold mechanoreceptors (LTMRs), but mechanisms terminating this program and allowing alternative fates are unknown. Here, we show that the conditional loss of the miR-183-96-182 cluster in mouse leads to a failure of extinction of Shox2 during development and an increase in the proportion of Aδ LTMRs (TRKB+/NECAB2+) neurons at the expense of Aß slowly adapting (SA)-LTMRs (TRKC+/Runx3-) neurons. Conversely, overexpression of miR-183 cluster that represses Shox2 expression, or loss of Shox2, both increase the Aß SA-LTMRs population at the expense of Aδ LTMRs. Our results suggest that the miR-183 cluster determines the timing of Shox2 expression by direct targeting during development, and through this determines the population sizes of Aδ LTMRs and Aß SA-LTMRs.
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Proteínas de Homeodominio/metabolismo , Mecanorreceptores/metabolismo , MicroARNs/genética , Células Receptoras Sensoriales/citología , Animales , Proteínas de Unión al Calcio/metabolismo , Diferenciación Celular/genética , Proteínas del Ojo/metabolismo , Femenino , Humanos , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Noqueados , Embarazo , Proteínas Tirosina Quinasas/metabolismoRESUMEN
A hierarchical hormonal cascade along the hypothalamic-pituitary-adrenal axis orchestrates bodily responses to stress. Although corticotropin-releasing hormone (CRH), produced by parvocellular neurons of the hypothalamic paraventricular nucleus (PVN) and released into the portal circulation at the median eminence, is known to prime downstream hormone release, the molecular mechanism regulating phasic CRH release remains poorly understood. Here, we find a cohort of parvocellular cells interspersed with magnocellular PVN neurons expressing secretagogin. Single-cell transcriptome analysis combined with protein interactome profiling identifies secretagogin neurons as a distinct CRH-releasing neuron population reliant on secretagogin's Ca(2+) sensor properties and protein interactions with the vesicular traffic and exocytosis release machineries to liberate this key hypothalamic releasing hormone. Pharmacological tools combined with RNA interference demonstrate that secretagogin's loss of function occludes adrenocorticotropic hormone release from the pituitary and lowers peripheral corticosterone levels in response to acute stress. Cumulatively, these data define a novel secretagogin neuronal locus and molecular axis underpinning stress responsiveness.
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Corticosterona/metabolismo , Hormona Liberadora de Corticotropina/metabolismo , Neuronas/metabolismo , Núcleo Hipotalámico Paraventricular/metabolismo , Secretagoginas/metabolismo , Estrés Fisiológico/fisiología , Animales , Corticosterona/genética , Hormona Liberadora de Corticotropina/genética , Masculino , Ratones , Neuronas/citología , Núcleo Hipotalámico Paraventricular/citología , Hipófisis/citología , Hipófisis/metabolismo , Interferencia de ARN , Secretagoginas/genética , Transcriptoma/fisiologíaRESUMEN
An increased incidence in the sleep-disorder narcolepsy has been associated with the 2009-2010 pandemic of H1N1 influenza virus in China and with mass vaccination campaigns against influenza during the pandemic in Finland and Sweden. Pathogenetic mechanisms of narcolepsy have so far mainly focused on autoimmunity. We here tested an alternative working hypothesis involving a direct role of influenza virus infection in the pathogenesis of narcolepsy in susceptible subjects. We show that infection with H1N1 influenza virus in mice that lack B and T cells (Recombinant activating gene 1-deficient mice) can lead to narcoleptic-like sleep-wake fragmentation and sleep structure alterations. Interestingly, the infection targeted brainstem and hypothalamic neurons, including orexin/hypocretin-producing neurons that regulate sleep-wake stability and are affected in narcolepsy. Because changes occurred in the absence of adaptive autoimmune responses, the findings show that brain infections with H1N1 virus have the potential to cause per se narcoleptic-like sleep disruption.
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Subtipo H1N1 del Virus de la Influenza A/fisiología , Narcolepsia/fisiopatología , Narcolepsia/virología , Neuronas/fisiología , Sueño , Vigilia , Animales , Antígenos Virales/inmunología , Electroencefalografía , Proteínas de Homeodominio/metabolismo , Hipotálamo/fisiopatología , Hipotálamo/virología , Inmunidad Innata , Ratones , Ratones Endogámicos C57BL , Modelos Neurológicos , Bulbo Olfatorio/fisiopatología , Bulbo Olfatorio/virología , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/fisiopatología , Infecciones por Orthomyxoviridae/virologíaRESUMEN
Pain is a critical component hindering recovery and regaining of function after surgery, particularly in the elderly. Understanding the role of pain signaling after surgery may lead to novel interventions for common complications such as delirium and postoperative cognitive dysfunction. Using a model of tibial fracture with intramedullary pinning in male mice, associated with cognitive deficits, we characterized the effects on the primary somatosensory system. Here we show that tibial fracture with pinning triggers cold allodynia and up-regulates nerve injury and inflammatory markers in dorsal root ganglia (DRGs) and spinal cord up to 2 wk after intervention. At 72 h after surgery, there is an increase in activating transcription factor 3 (ATF3), the neuropeptides galanin and neuropeptide Y (NPY), brain-derived neurotrophic factor (BDNF), as well as neuroinflammatory markers including ionized calcium-binding adaptor molecule 1 (Iba1), glial fibrillary acidic protein (GFAP), and the fractalkine receptor CX3CR1 in DRGs. Using an established model of complete transection of the sciatic nerve for comparison, we observed similar but more pronounced changes in these markers. However, protein levels of BDNF remained elevated for a longer period after fracture. In the hippocampus, BDNF protein levels were increased, yet there were no changes in Bdnf mRNA in the parent granule cell bodies. Further, c-Fos was down-regulated in the hippocampus, together with a reduction in neurogenesis in the subgranular zone. Taken together, our results suggest that attenuated BDNF release and signaling in the dentate gyrus may account for cognitive and mental deficits sometimes observed after surgery.
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Factor Neurotrófico Derivado del Encéfalo/genética , Disfunción Cognitiva/genética , Giro Dentado/metabolismo , Ganglios Espinales/metabolismo , Neuropéptido Y/genética , Dolor/genética , Fracturas de la Tibia/cirugía , Factor de Transcripción Activador 3/genética , Factor de Transcripción Activador 3/metabolismo , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Receptor 1 de Quimiocinas CX3C/genética , Receptor 1 de Quimiocinas CX3C/metabolismo , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Disfunción Cognitiva/etiología , Disfunción Cognitiva/metabolismo , Disfunción Cognitiva/patología , Giro Dentado/fisiopatología , Fijación Intramedular de Fracturas/efectos adversos , Galanina/genética , Galanina/metabolismo , Ganglios Espinales/fisiopatología , Regulación de la Expresión Génica , Proteína Ácida Fibrilar de la Glía/genética , Proteína Ácida Fibrilar de la Glía/metabolismo , Hiperalgesia/genética , Hiperalgesia/metabolismo , Hiperalgesia/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas de Microfilamentos/genética , Proteínas de Microfilamentos/metabolismo , Neuropéptido Y/metabolismo , Dolor/etiología , Dolor/metabolismo , Dolor/patología , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-fos/metabolismo , Nervio Ciático/lesiones , Nervio Ciático/metabolismo , Transducción de Señal , Médula Espinal/metabolismo , Médula Espinal/fisiopatología , Fracturas de la Tibia/genética , Fracturas de la Tibia/metabolismo , Fracturas de la Tibia/fisiopatologíaRESUMEN
The neuropeptide galanin coexists in rat brain with serotonin in the dorsal raphe nucleus and with noradrenaline in the locus coeruleus (LC), and it has been suggested to be involved in depression. We studied rats exposed to chronic mild stress (CMS), a rodent model of depression. As expected, these rats showed several endophenotypes relevant to depression-like behavior compared with controls. All these endophenotypes were normalized after administration of a selective serotonin reuptake inhibitor. The transcripts for galanin and two of its receptors, galanin receptor 1 (GALR1) and GALR2, were analyzed with quantitative real-time PCR using laser capture microdissection in the following brain regions: the hippocampal formation, LC, and ventral periaqueductal gray (vPAG). Only Galr1 mRNA levels were significantly increased, and only in the latter region. After knocking down Galr1 in the vPAG with an siRNA technique, all parameters of the depressive behavioral phenotype were similar to controls. Thus, the depression-like behavior in rats exposed to CMS is likely related to an elevated expression of Galr1 in the vPAG, suggesting that a GALR1 antagonist could have antidepressant effects.
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Depresión/etiología , Sustancia Gris Periacueductal/fisiología , Receptor de Galanina Tipo 1/fisiología , Animales , Depresión/tratamiento farmacológico , Modelos Animales de Enfermedad , Locus Coeruleus/fisiología , Masculino , Ratas , Ratas Sprague-Dawley , Receptor de Galanina Tipo 1/antagonistas & inhibidores , Serotonina/fisiología , Ácido gamma-Aminobutírico/fisiologíaRESUMEN
Although extensively studied postnatally, the functional differentiation of cholecystokinin (CCK)-containing interneurons en route towards the cerebral cortex during fetal development is incompletely understood. Here, we used CCKBAC/DsRed mice encoding a CCK promoter-driven red fluorescent protein to analyze the temporal dynamics of DsRed expression, neuronal identity, and positioning through high-resolution developmental neuroanatomy. Additionally, we developed a dual reporter mouse line (CCKBAC/DsRed::GAD67gfp/+) to differentiate CCK-containing interneurons from DsRed+ principal cells during prenatal development. We show that DsRed is upregulated in interneurons once they exit their proliferative niche in the ganglionic eminence and remains stably expressed throughout their long-distance migration towards the cerebrum, particularly in the hippocampus. DsRed+ interneurons, including a cohort coexpressing calretinin, accumulated at the palliosubpallial boundary by embryonic day 12.5. Pioneer DsRed+ interneurons already reached deep hippocampal layers by embryonic day 14.5 and were morphologically differentiated by birth. Furthermore, we probed migrating interneurons entering and traversing the cortical plate, as well as stationary cells in the hippocampus by patch-clamp electrophysiology to show the first signs of Na+ and K+ channel activity by embryonic day 12.5 and reliable adult-like excitability by embryonic day 18.5. Cumulatively, this study defines key positional, molecular, and biophysical properties of CCK+ interneurons in the prenatal brain.
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Diferenciación Celular/fisiología , Corteza Cerebral/citología , Colecistoquinina/metabolismo , Interneuronas/citología , Neurogénesis/fisiología , Animales , Movimiento Celular , Corteza Cerebral/embriología , Corteza Cerebral/metabolismo , Inmunohistoquímica , Hibridación in Situ , Interneuronas/metabolismo , Ratones , Ratones Transgénicos , Microscopía Confocal , Técnicas de Placa-ClampRESUMEN
Neuronal calcium (Ca(2+))-binding proteins 1 and 2 (NECAB1/2) are members of the phylogenetically conserved EF-hand Ca(2+)-binding protein superfamily. To date, NECABs have been explored only to a limited extent and, so far, not at all at the spinal level. Here, we describe the distribution, phenotype, and nerve injury-induced regulation of NECAB1/NECAB2 in mouse dorsal root ganglia (DRGs) and spinal cord. In DRGs, NECAB1/2 are expressed in around 70% of mainly small- and medium-sized neurons. Many colocalize with calcitonin gene-related peptide and isolectin B4, and thus represent nociceptors. NECAB1/2 neurons are much more abundant in DRGs than the Ca(2+)-binding proteins (parvalbumin, calbindin, calretinin, and secretagogin) studied to date. In the spinal cord, the NECAB1/2 distribution is mainly complementary. NECAB1 labels interneurons and a plexus of processes in superficial layers of the dorsal horn, commissural neurons in the intermediate area, and motor neurons in the ventral horn. Using CLARITY, a novel, bilaterally connected neuronal system with dendrites that embrace the dorsal columns like palisades is observed. NECAB2 is present in cell bodies and presynaptic boutons across the spinal cord. In the dorsal horn, most NECAB1/2 neurons are glutamatergic. Both NECAB1/2 are transported into dorsal roots and peripheral nerves. Peripheral nerve injury reduces NECAB2, but not NECAB1, expression in DRG neurons. Our study identifies NECAB1/2 as abundant Ca(2+)-binding proteins in pain-related DRG neurons and a variety of spinal systems, providing molecular markers for known and unknown neuron populations of mechanosensory and pain circuits in the spinal cord.
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Proteínas de Unión al Calcio/metabolismo , Ganglios Espinales/metabolismo , Neuronas/metabolismo , Traumatismos de los Nervios Periféricos/metabolismo , Médula Espinal/citología , Animales , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Dolor/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Médula Espinal/metabolismoRESUMEN
Diabetic peripheral neuropathy (DPN) is the most common complication in both type 1 and type 2 diabetes. Here we studied some phenotypic features of a well-established animal model of type 2 diabetes, the leptin receptor-deficient db(-)/db(-) mouse, and also the effect of long-term (6 mo) treatment with coenzyme Q10 (CoQ10), an endogenous antioxidant. Diabetic mice at 8 mo of age exhibited loss of sensation, hypoalgesia (an increase in mechanical threshold), and decreases in mechanical hyperalgesia, cold allodynia, and sciatic nerve conduction velocity. All these changes were virtually completely absent after the 6-mo, daily CoQ10 treatment in db(-)/db(-) mice when started at 7 wk of age. There was a 33% neuronal loss in the lumbar 5 dorsal root ganglia (DRGs) of the db(-)/db(-) mouse versus controls at 8 mo of age, which was significantly attenuated by CoQ10. There was no difference in neuron number in 5/6-wk-old mice between diabetic and control mice. We observed a strong down-regulation of phospholipase C (PLC) ß3 in the DRGs of diabetic mice at 8 mo of age, a key molecule in pain signaling, and this effect was also blocked by the 6-mo CoQ10 treatment. Many of the phenotypic, neurochemical regulations encountered in lumbar DRGs in standard models of peripheral nerve injury were not observed in diabetic mice at 8 mo of age. These results suggest that reactive oxygen species and reduced PLCß3 expression may contribute to the sensory deficits in the late-stage diabetic db(-)/db(-) mouse, and that early long-term administration of the antioxidant CoQ10 may represent a promising therapeutic strategy for type 2 diabetes neuropathy.
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Diabetes Mellitus Tipo 2/complicaciones , Neuronas/efectos de los fármacos , Enfermedades del Sistema Nervioso Periférico/prevención & control , Receptores de Leptina/deficiencia , Ubiquinona/análogos & derivados , Factores de Edad , Animales , Western Blotting , Diabetes Mellitus Tipo 2/patología , Estimulación Eléctrica , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/metabolismo , Hiperalgesia/patología , Inmunohistoquímica , Hibridación in Situ , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Conducción Nerviosa/efectos de los fármacos , Enfermedades del Sistema Nervioso Periférico/etiología , Fosfolipasa C beta/metabolismo , Receptores de Leptina/genética , Nervio Ciático/lesiones , Nervio Ciático/patología , Estadísticas no Paramétricas , Ubiquinona/farmacologíaRESUMEN
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.
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Ganglios Espinales/patología , Receptores de Somatostatina/metabolismo , Ciática/metabolismo , Ciática/patología , Células Receptoras Sensoriales/metabolismo , Somatostatina/metabolismo , Animales , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Femenino , Lateralidad Funcional/genética , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Glutamato Descarboxilasa/genética , Proteínas Fluorescentes Verdes/deficiencia , Proteínas Fluorescentes Verdes/genética , Humanos , Hiperalgesia/tratamiento farmacológico , Hiperalgesia/etiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Persona de Mediana Edad , Octreótido/uso terapéutico , Oligopéptidos/farmacología , Umbral del Dolor/efectos de los fármacos , Umbral del Dolor/fisiología , Transporte de Proteínas/efectos de los fármacos , Transporte de Proteínas/genética , Receptores de Somatostatina/antagonistas & inhibidores , Receptores de Somatostatina/deficiencia , Receptores de Somatostatina/genética , Ciática/complicaciones , Ciática/tratamiento farmacológico , Células Receptoras Sensoriales/efectos de los fármacos , Somatostatina/genéticaRESUMEN
Previous work identified nociceptive Schwann cells that can initiate pain. Consistent with the existence of inherently mechanosensitive sensory Schwann cells, we found that in mice, the mechanosensory function of almost all nociceptors, including those signaling fast pain, were dependent on sensory Schwann cells. In polymodal nociceptors, sensory Schwann cells signal mechanical, but not cold or heat pain. Terminal Schwann cells also surround mechanoreceptor nerve-endings within the Meissner's corpuscle and in hair follicle lanceolate endings that both signal vibrotactile touch. Within Meissner´s corpuscles, two molecularly and functionally distinct sensory Schwann cells positive for Sox10 and Sox2 differentially modulate rapidly adapting mechanoreceptor function. Using optogenetics we show that Meissner's corpuscle Schwann cells are necessary for the perception of low threshold vibrotactile stimuli. These results show that sensory Schwann cells within diverse glio-neural mechanosensory end-organs are sensors for mechanical pain as well as necessary for touch perception.
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Percepción del Tacto , Tacto , Ratones , Animales , Tacto/fisiología , Nocicepción , Percepción del Tacto/fisiología , Mecanorreceptores/fisiología , Células de Schwann , Dolor , Umbral SensorialRESUMEN
BACKGROUND: Secretagogin (Scgn), a member of the EF-hand calcium-binding protein (CaBP) superfamily, has recently been found in subsets of developing and adult neurons. Here, we have analyzed the expression of Scgn in dorsal root ganglia (DRGs) and trigeminal ganglia (TGs), and in spinal cord of mouse at the mRNA and protein levels, and in comparison to the well-known CaBPs, calbindin D-28k, parvalbumin and calretinin. Rat DRGs, TGs and spinal cord, as well as human DRGs and spinal cord were used to reveal phylogenetic variations. RESULTS: We found Scgn mRNA expressed in mouse and human DRGs and in mouse ventral spinal cord. Our immunohistochemical data showed a complementary distribution of Scgn and the three CaBPs in mouse DRG neurons and spinal cord. Scgn was expressed in ~7% of all mouse DRG neuron profiles, mainly small ones and almost exclusively co-localized with calcitonin gene-related peptide (CGRP). This co-localization was also seen in human, but not in rat DRGs. Scgn could be detected in the mouse sciatic nerve and accumulated proximal to its constriction. In mouse spinal cord, Scgn-positive neuronal cell bodies and fibers were found in gray matter, especially in the dorsal horn, with particularly high concentrations of fibers in the superficial laminae, as well as in cell bodies in inner lamina II and in some other laminae. A dense Scgn-positive fiber network and some small cell bodies were also found in the superficial dorsal horn of humans. In the ventral horn, a small number of neurons were Scgn-positive in mouse but not rat, confirming mRNA distribution. Both in mouse and rat, a subset of TG neurons contained Scgn. Dorsal rhizotomy strongly reduced Scgn fiber staining in the dorsal horn. Peripheral axotomy did not clearly affect Scgn expression in DRGs, dorsal horn or ventral horn neurons in mouse. CONCLUSIONS: Scgn is a CaBP expressed in a subpopulation of nociceptive DRG neurons and their processes in the dorsal horn of mouse, human and rat, the former two co-expressing CGRP, as well as in dorsal horn neurons in all three species. Functional implications of these findings include the cellular refinement of sensory information, in particular during the processing of pain.
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Péptido Relacionado con Gen de Calcitonina/metabolismo , Proteínas de Unión al Calcio/metabolismo , Neuronas Aferentes/citología , Neuronas Aferentes/metabolismo , Células Receptoras Sensoriales/metabolismo , Médula Espinal/metabolismo , Animales , Péptido Relacionado con Gen de Calcitonina/genética , Proteínas de Unión al Calcio/genética , Humanos , Masculino , Ratones , Ratas , Secretagoginas , Células Receptoras Sensoriales/citología , Médula Espinal/citologíaRESUMEN
Specialized cutaneous Schwann cells (SCs), termed nociceptive SCs, were recently discovered. Their function is not fully understood, but they are believed not only to support peripheral axons in mouse skin by forming a mesh-like neural-glio networking structure in subepidermal area, but also contributing to transduction of mechanical sensation and neuropathic pain. Diabetic neuropathy (DPN) is one of the most common complication of diabetes, however, the mechanisms behind painful and painless DPN remain unclear. Using a mouse model of DPN, we want to investigate if there are quantitative differences in nociceptive SC density between the condition of hyperglycemia-induced sensory abnormalities and control condition and at which stage in the disease the damage occurs. Here, we developed a set of counting rules for nociceptive SCs based on immunofluorescent staining, and applied the method to quantify the density of nociceptive SCs in control mice (n = 10), mice with nociceptive hypersensitivity at early diabetic stage (n = 5), and mice with sensory hyposensitivity at late diabetic stage (n = 5) in the Streptozotocin (STZ) model of type 1 diabetes. Nociceptive SCs were identified as S100+/Sox10+/DAPI+ cells abutting to peripheral nerves, with the somas located within 25 µm depth in the subepidermal area and outside glands and large fiber bundles. Hypersensitive diabetic mice had decreased nociceptive SC density, despite having normal epidermal nerve fiber density, compared with age-matched control mice (P = 0.023). In contrast, there was a reduction in intraepidermal nerve fiber density but no difference in nociceptive SC density between hyposensitive diabetic mice and the age-matched control mice. This study provides a detailed description of how to identify and quantify nociceptive SC and demonstrates that nociceptive SC density declines before nerve fiber deterioration, which supports previous observations that nociceptive SCs are critical for maintenance of cutaneous sensory nerves.
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Diabetes Mellitus Experimental , Neuropatías Diabéticas , Animales , Nocicepción , Células de Schwann , EstreptozocinaRESUMEN
Glioblastoma is believed to originate from nervous system cells; however, a putative origin from vessel-associated progenitor cells has not been considered. We deeply single-cell RNA-sequenced glioblastoma progenitor cells of 18 patients and integrated 710 bulk tumors and 73,495 glioma single cells of 100 patients to determine the relation of glioblastoma cells to normal brain cell types. A novel neural network-based projection of the developmental trajectory of normal brain cells uncovered two principal cell-lineage features of glioblastoma, neural crest perivascular and radial glia, carrying defining methylation patterns and survival differences. Consistently, introducing tumorigenic alterations in naïve human brain perivascular cells resulted in brain tumors. Thus, our results suggest that glioblastoma can arise from the brains' vasculature, and patients with such glioblastoma have a significantly poorer outcome.
RESUMEN
ABSTRACT: Recent findings indicate that nociceptive nerves are not "free", but similar to touch and pressure sensitive nerves, terminate in an end-organ in mice. This sensory structure consists of the nociceptive nerves and specialized nociceptive Schwann cells forming a mesh-like organ in subepidermis with pain transduction initiated at both these cellular constituents. The intimate relation of nociceptive nerves with nociceptive Schwann cells in mice raises the question whether defects in nociceptive Schwann cells can by itself contribute to pain hyperalgesia, nerve retraction, and peripheral neuropathy. We therefore examined the existence of nociceptive Schwann cells in human skin and their possible contribution to neuropathy and pain hyperalgesia in mouse models. Similar to mouse, human skin contains SOX10+/S100B+/AQP1+ Schwann cells in the subepidermal border that have extensive processes, which are intimately associated with nociceptive nerves projecting into epidermis. The ablation of nociceptive Schwann cells in mice resulted in nerve retraction and mechanical, cold, and heat hyperalgesia. Conversely, ablating the nociceptive nerves led to a retraction of epidermal Schwann cell processes, changes in nociceptive Schwann cell soma morphology, heat analgesia, and mechanical hyperalgesia. Our results provide evidence for a nociceptive sensory end-organ in the human skin and using animal models highlight the interdependence of the nerve and the nociceptive Schwann cell. Finally, we show that demise of nociceptive Schwann cells is sufficient to cause neuropathic-like pain in the mouse.
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Hiperalgesia , Nocicepción , Animales , Ratones , Dolor , Dimensión del Dolor , Células de SchwannRESUMEN
Voltage-gated sodium channels (Navs) 1.7, 1.8, and 1.9 are predominately expressed in peripheral sensory neurons and are critical for action potential propagation in nociceptors. Unexpectedly, we found that expression of SCN9A, SCN10A, SCN11A, and SCN2A, the alpha subunit of Nav1.7, Nav1.8, Nav1.9 and Nav1.2, respectively, are up-regulated in spinal dorsal horn (SDH) neurons of miR-96 knockout mice. These mice also have de-repression of CACNA2D1/2 in DRG and display thermal and mechanical allodynia that could be attenuated by intrathecal or intraperitoneal injection of Nav1.7 or Nav1.8 blockers or Gabapentin. Moreover, Gad2::CreERT2 conditional miR-96 knockout mice phenocopied global knockout mice, implicating inhibitory neurons; nerve injury induced significant loss of miR-96 in SDH GABAergic and Glutamatergic neurons in mice which negatively correlated to up-regulation of Nav1.7, Nav1.8, Nav1.9 and Scn2a, this dis-regulation of miR-96 and Navs in SDH neurons contributed to neuropathic pain which can be alleviated by intrathecal injection of Nav1.7 or Nav1.8 blockers. In conclusion, miR-96 is required to avoid allodynia through limiting the expression of VGCCs and Navs in DRG and Navs in SDH in naïve and nerve injury-induced neuropathic pain mice. Our findings suggest that central nervous system penetrating Nav1.7 and Nav1.8 blockers may be efficacious for pain relief.
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MicroARNs , Neuralgia , Canales de Sodio Activados por Voltaje , Animales , Canales de Calcio , Ganglios Espinales , Hiperalgesia/tratamiento farmacológico , Ratones , MicroARNs/genética , Canal de Sodio Activado por Voltaje NAV1.8/genética , Canal de Sodio Activado por Voltaje NAV1.9 , Ratas , Ratas Sprague-Dawley , Médula EspinalRESUMEN
An essential prerequisite for the survival of an organism is the ability to detect and respond to aversive stimuli. Current belief is that noxious stimuli directly activate nociceptive sensory nerve endings in the skin. We discovered a specialized cutaneous glial cell type with extensive processes forming a mesh-like network in the subepidermal border of the skin that conveys noxious thermal and mechanical sensitivity. We demonstrate a direct excitatory functional connection to sensory neurons and provide evidence of a previously unknown organ that has an essential physiological role in sensing noxious stimuli. Thus, these glial cells, which are intimately associated with unmyelinated nociceptive nerves, are inherently mechanosensitive and transmit nociceptive information to the nerve.
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Percepción del Dolor/fisiología , Células de Schwann/fisiología , Piel/inervación , Animales , Femenino , Masculino , Mecanorreceptores/fisiología , Ratones , Ratones Endogámicos C57BL , Nociceptores/fisiología , Optogenética , Umbral del Dolor , Factores de Transcripción SOXE/genética , Factores de Transcripción SOXE/metabolismo , Células de Schwann/metabolismo , Termorreceptores/fisiologíaRESUMEN
The sensation of pain is essential for the preservation of the functional integrity of the body. However, the key molecular regulators necessary for the initiation of the development of pain-sensing neurons have remained largely unknown. Here, we report that, in mice, inactivation of the transcriptional regulator PRDM12, which is essential for pain perception in humans, results in a complete absence of the nociceptive lineage, while proprioceptive and touch-sensitive neurons remain. Mechanistically, our data reveal that PRDM12 is required for initiation of neurogenesis and activation of a cascade of downstream pro-neuronal transcription factors, including NEUROD1, BRN3A, and ISL1, in the nociceptive lineage while it represses alternative fates other than nociceptors in progenitor cells. Our results thus demonstrate that PRDM12 is necessary for the generation of the entire lineage of pain-initiating neurons.
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Proteínas Portadoras/fisiología , Proteínas del Tejido Nervioso/fisiología , Neurogénesis/fisiología , Neuronas/fisiología , Nociceptores/fisiología , Animales , Proteínas Portadoras/genética , Linaje de la Célula , Pollos , Femenino , Perfilación de la Expresión Génica , Inmunohistoquímica , Masculino , Ratones , Proteínas del Tejido Nervioso/genética , Neurogénesis/genética , Nocicepción/fisiología , Factores de Transcripción/metabolismoRESUMEN
Pain signals are transmitted by multisynaptic glutamatergic pathways. Their first synapse between primary nociceptors and excitatory spinal interneurons gates the sensory load. In this pathway, glutamate release is orchestrated by Ca2+-sensor proteins, with N-terminal EF-hand Ca2+-binding protein 2 (NECAB2) being particular abundant. However, neither the importance of NECAB2+ neuronal contingents in dorsal root ganglia (DRGs) and spinal cord nor the function determination by NECAB2 has been defined. A combination of histochemical analyses and single-cell RNA-sequencing showed NECAB2 in small- and medium-sized C- and Aδ D-hair low-threshold mechanoreceptors in DRGs, as well as in protein kinase C γ excitatory spinal interneurons. NECAB2 was downregulated by peripheral nerve injury, leading to the hypothesis that NECAB2 loss of function could limit pain sensation. Indeed, Necab2-/- mice reached a pain-free state significantly faster after peripheral inflammation than did WT littermates. Genetic access to transiently activated neurons revealed that a mediodorsal cohort of NECAB2+ neurons mediates inflammatory pain in the mouse spinal dorsal horn. Here, besides dampening excitatory transmission in spinal interneurons, NECAB2 limited pronociceptive brain-derived neurotrophic factor (BDNF) release from sensory afferents. Hoxb8-dependent reinstatement of NECAB2 expression in Necab2-/- mice then demonstrated that spinal and DRG NECAB2 alone could control inflammation-induced sensory hypersensitivity. Overall, we identify NECAB2 as a critical component of pronociceptive pain signaling, whose inactivation offers substantial pain relief.
Asunto(s)
Proteínas de Unión al Calcio/fisiología , Proteínas del Ojo/fisiología , Hiperalgesia/etiología , Hiperalgesia/fisiopatología , Dolor/etiología , Dolor/fisiopatología , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Proteínas de Unión al Calcio/deficiencia , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Regulación hacia Abajo , Proteínas del Ojo/genética , Femenino , Ganglios Espinales/fisiopatología , Hiperalgesia/genética , Inflamación/fisiopatología , Interneuronas/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Nociceptores/fisiología , Dolor/genética , Traumatismos de los Nervios Periféricos/genética , Traumatismos de los Nervios Periféricos/fisiopatología , Secretagoginas/deficiencia , Secretagoginas/genética , Secretagoginas/metabolismo , Médula Espinal/fisiopatología , Asta Dorsal de la Médula Espinal/fisiopatologíaRESUMEN
Nociception is protective and prevents tissue damage but can also facilitate chronic pain. Whether a general principle governs these two types of pain is unknown. Here, we show that both basal mechanical and neuropathic pain are controlled by the microRNA-183 (miR-183) cluster in mice. This single cluster controls more than 80% of neuropathic pain-regulated genes and scales basal mechanical sensitivity and mechanical allodynia by regulating auxiliary voltage-gated calcium channel subunits α2δ-1 and α2δ-2. Basal sensitivity is controlled in nociceptors, and allodynia involves TrkB+ light-touch mechanoreceptors. These light-touch-sensitive neurons, which normally do not elicit pain, produce pain during neuropathy that is reversed by gabapentin. Thus, a single microRNA cluster continuously scales acute noxious mechanical sensitivity in nociceptive neurons and suppresses neuropathic pain transduction in a specific, light-touch-sensitive neuronal type recruited during mechanical allodynia.