RESUMO
Surgical intervention is necessary following nerve trauma. Tubular prostheses can guide growing axons and inserting substances within these prostheses can be positive for the regeneration, making it an alternative for the current standard tools for nerve repair. Our aim was to investigate the effects of fibrin glue BthTL when combined with a synthetic TNF mimetic-action peptide on nerve regeneration. Male Wistar rats suffered left sciatic nerve transection. For repairing, we used empty silicon tubes (n = 10), tubes filled with fibrin glue BthTL (Tube + Glue group, n = 10) or tubes filled with fibrin glue BThTL mixed with TNF mimetic peptide (Tube + Glue + Pep group, n = 10). Animals were euthanized after 45 days. We collected nerves to perform immunostaining (neurofilament, GAP43, S100-ß, NGFRp75 and Iba-1), light and transmission electron microscopy (for counting myelinated, unmyelinated and degenerated fibers; and for the evaluation of morphometric aspects of regenerated fibers) and collagen staining. All procedures were approved by local ethics committee (protocol 063/17). Tube + Glue + Pep group showed intense inflammatory infiltrate, higher Iba-1 expression, increased immunostaining for NGFRp75 receptor (which characterizes Schwann cell regenerative phenotype), higher myelin thickness and fiber diameter and more type III collagen deposition. Tube + Glue group showed intermediate results between empty tube and Tube + Glue + Pep groups for anti-NGFRp75 immunostaining, inflammation and collagen; on fiber counts, this group showed more degenerate fibers and fewer unmyelinated axons than others. Empty tube group showed superiority only in GAP43 immunostaining. A combination of BthTL glue and TNF mimetic peptide induced greater axonal regrowth and remyelination.
Assuntos
Adesivo Tecidual de Fibrina , Regeneração Nervosa/efeitos dos fármacos , Peptidomiméticos/administração & dosagem , Peptidomiméticos/farmacologia , Nervos Periféricos/efeitos dos fármacos , Fator de Necrose Tumoral alfa/administração & dosagem , Fator de Necrose Tumoral alfa/farmacologia , Animais , Axônios/efeitos dos fármacos , Colágeno/metabolismo , Imuno-Histoquímica , Masculino , Bainha de Mielina/efeitos dos fármacos , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Proteínas do Tecido Nervoso/metabolismo , Peptidomiméticos/química , Ratos , Ratos Wistar , Células de Schwann/efeitos dos fármacos , Células de Schwann/ultraestrutura , Nervo Isquiático/lesões , Fator de Necrose Tumoral alfa/químicaRESUMO
Maternal anesthetic exposure during pregnancy is associated with an increased risk of cognitive impairment in offspring. The balance of cerebral iron metabolism is essential for the development of brain tissue. Iron deficiency affects the myelinogenesis and nerve tissue development, especially in fetus or infant, which has a key role in cognitive function. We aimed to investigate whether maternal sevoflurane (Sev) exposure caused cognitive impairment in offspring through inducing iron deficiency and inhibiting myelinogenesis. Pregnant mice (gestation stage day 14) were treated with 2% Sev for 6 h. Cognitive function of offspring mice was determined by the Morris water maze and Context fear conditioning test. Iron levels were assayed by Perl's iron staining and synchrotron imaging. Hippocampus and cortex tissues or cerebral microvascular endothelial cells of offspring mice (postnatal day 35) were harvested and subjected to Western blot and/or immunhistochemistry to assess ferritin, transferrin receptor 1(TfR1), Ferroportin-1 (FpN1), myelin basic protein (MBP), tight junction protein ZO-1, occludin, and claudin-5 levels. Beginning with postnatal day 30, the offspring were treated with iron therapy for 30 days, and the indicators above were tested. Our results showed Sev dramatically decreased the iron levels of brain and impaired cognitive function in offspring mice. Sev decreased the expression of heavy chain ferritin (FtH), light chain ferritin (FtL), MBP, ZO-1, occludin, claudin-5, and FpN1, and increased TfR1 in hippocampus and cortex or cerebral microvascular endothelial cells of offspring mice, indicating that Sev caused the iron deficiency and impaired the myelinogenesis in the brain of offspring. Interestingly, iron therapy prompted the myelinogenesis and improved impaired cognitive function at postnatal day 60. Our research uncovered a new mechanism which showed that iron deficiency induced by Sev and myelin formation disorder due to decreased iron of brain may be an important risk factor for cognitive impairment in offspring. It was necessary for offspring to be supplied iron supplement whose mother suffered exposure to sevoflurane during pregnancy.
Assuntos
Anemia Ferropriva/induzido quimicamente , Anestésicos Inalatórios/toxicidade , Disfunção Cognitiva/induzido quimicamente , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Sevoflurano/toxicidade , Administração por Inalação , Anemia Ferropriva/metabolismo , Anemia Ferropriva/patologia , Anestésicos Inalatórios/administração & dosagem , Animais , Disfunção Cognitiva/metabolismo , Disfunção Cognitiva/patologia , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Mielinizadas/patologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Efeitos Tardios da Exposição Pré-Natal/patologia , Sevoflurano/administração & dosagemRESUMO
Migraine is a strongly disabling disease characterized by a unilateral throbbing headache lasting for up to 72 h for each individual attack. There have been many theories on the pathophysiology of migraine throughout the years. Currently, the neurovascular theory dominates, suggesting clear involvement of the trigeminovascular system. The most recent data show that a migraine attack most likely originates in the hypothalamus and activates the trigeminal nucleus caudalis (TNC). Although the mechanisms are unknown, activation of the TNC leads to peripheral release of calcitonin gene-related protein (CGRP), most likely from C-fibers. During the past year monoclonal antibodies against CGRP or the CGRP receptor have emerged as the most promising targets for migraine therapy, and at the same time established the strong involvement of CGRP in the pathophysiology of migraine. The viewpoint presented here focuses further on the activation of the CGRP receptor on the sensory Aδ-fiber, leading to the sensation of pain. The CGRP receptor activates adenylate cyclase, which leads to an increase in cyclic adenosine monophosphate (cAMP). We hypothesize that cAMP activates the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, triggering an action potential sensed as pain. The mechanisms behind migraine pain on a molecular level, particularly their importance to cAMP, provide clues to potential new anti-migraine targets. In this article we focus on the development of targets related to the CGRP system, and further include novel targets such as the pituitary adenylate cyclase-activating peptide (PACAP) system, the serotonin 5-HT1F receptor, purinergic receptors, HCN channels, adenosine triphosphate-sensitive potassium channels (KATP), and the glutaminergic system.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Desenvolvimento de Medicamentos/métodos , Transtornos de Enxaqueca/tratamento farmacológico , Transtornos de Enxaqueca/metabolismo , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/metabolismo , AMP Cíclico/metabolismo , Humanos , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Terapia de Alvo Molecular , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Amielínicas/efeitos dos fármacos , Fibras Nervosas Amielínicas/metabolismo , Gânglio Trigeminal/efeitos dos fármacos , Gânglio Trigeminal/metabolismo , Núcleos do Trigêmeo/efeitos dos fármacos , Núcleos do Trigêmeo/metabolismoRESUMO
Estrogen replacement therapy (ERT) improves hippocampus-dependent cognition. This study investigated the impact of estrogen on hippocampal volume, CA1 subfield volume and myelinated fibers in the CA1 subfield of middle-aged ovariectomized rats. Ten-month-old bilaterally ovariectomized (OVX) female rats were randomly divided into OVXâ¯+â¯E2 and OVXâ¯+â¯Veh groups. After four weeks of subcutaneous injection with 17ß-estradiol or a placebo, the OVXâ¯+â¯E2 rats exhibited significantly short mean escape latency in a spatial learning task than that in the OVXâ¯+â¯Veh rats. Using stereological methods, we did not observe significant differences in the volumes of the hippocampus and CA1 subfields between the two groups. However, using stereological methods and electron microscopy techniques, the total length of myelinated fibers and the total volumes of myelinated fibers, myelin sheaths and myelinated axons in the CA1 subfields of OVXâ¯+â¯E2 rats were significantly 38.1%, 34.2%, 36.1% and 32.5%, respectively, higher than those in the OVXâ¯+â¯Veh rats. After the parameters were calculated according to different diameter ranges, the estrogen replacement-induced remodeling of myelinated fibers in CA1 was mainly manifested in the myelinated fibers with a diameter of <1.0⯵m. Therefore, four weeks of continuous E2 replacement improved the spatial learning capabilities of middle-aged ovariectomized rats. The E2 replacement-induced protection of spatial learning abilities might be associated with the beneficial effects of estrogen on myelinated fibers, particularly those with the diameters less than 1.0⯵m, in the hippocampal CA1 region of middle-aged ovariectomized rats.
Assuntos
Estradiol/farmacologia , Hipocampo/efeitos dos fármacos , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Aprendizagem Espacial/efeitos dos fármacos , Animais , Região CA1 Hipocampal/anatomia & histologia , Região CA1 Hipocampal/efeitos dos fármacos , Terapia de Reposição de Estrogênios , Feminino , Hipocampo/anatomia & histologia , Tamanho do Órgão/efeitos dos fármacos , Ovariectomia , Ratos , Ratos Sprague-DawleyRESUMO
AIMS: We investigated the effects of silodosin, an α1A-adrenoceptor (AR) antagonist, on bladder function, especially on non-voiding contractions (NVCs), in a male rat model of bladder outlet obstruction (BOO) by evaluating cystometry (CMG) findings and bladder mechanosensitive single-unit afferent activities (SAAs), related with microcontractions, which may be similar with NVCs and to be of myogenic origin, in the rat model. METHODS: BOO was created by partial ligation of the posterior urethra. At 4 days after surgery for BOO, an osmotic pump filled with silodosin (0.12 mg/kg/day) or its vehicle was subcutaneously implanted. At 10 days after surgery, CMG and SAAs measurements were taken under conscious and urethane-anesthetized conditions, respectively. The SAAs of Aδ- and C-fibers, which were identified by electrical stimulation of the pelvic nerve and by bladder distention, and intravesical pressure were recorded during constant bladder-filling with saline. Microcontractions were divided into three phases: "ascending," "descending," and "stationary." RESULTS: The silodosin-treated group showed a smaller number of NVCs in CMG measurements and lower SAAs of both Aδ- and C-fibers than the vehicle-treated group during bladder-filling. Moreover, in the vehicle-treated groups, the SAAs of both fibers for the ascending phase of microcontractions were significantly higher than those for the other two phases. On the contrary, no significant change was found between any of these three phases in the silodosin-treated group. CONCLUSION: The present results suggest that silodosin inhibits the SAAs of mechanosensitive Aδ- and C-fibers at least partly due to suppressing myogenic bladder contractions in male BOO rats.
Assuntos
Antagonistas de Receptores Adrenérgicos alfa 1/farmacologia , Indóis/farmacologia , Mecanorreceptores/efeitos dos fármacos , Neurônios Aferentes/efeitos dos fármacos , Obstrução do Colo da Bexiga Urinária/fisiopatologia , Bexiga Urinária/efeitos dos fármacos , Bexiga Urinária/inervação , Agentes Urológicos/farmacologia , Antagonistas de Receptores Adrenérgicos alfa 1/administração & dosagem , Animais , Implantes de Medicamento , Estimulação Elétrica , Indóis/administração & dosagem , Masculino , Contração Muscular/efeitos dos fármacos , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Amielínicas/efeitos dos fármacos , Ratos , Ratos Wistar , Agentes Urológicos/administração & dosagemRESUMO
Elevated levels of endogenous estrogens in the course of pathological states of ovaries, as well as xenoestrogens, may lead to hyperestrogenism. It has previously been demonstrated that long-term estradiol-17ß (E2) administration in adult gilts affected the population of sympathetic intraovarian nerve fibers. The aim of this study has been to determine the effect of long-term E2 exposure on the cholinergic innervation pattern of porcine ovaries. Intraovarian distribution and the density of nerve fibers immunoreactive (IR) to vesicular acetylocholine transporter (VAChT) and/or neuronal isoform of nitric oxide synthase (nNOS), vasoactive intestinal polypeptide (VIP), somatostatin (SOM) were determined. From day 4 of the first estrous cycle to day 20 of the second studied cycle, experimental gilts were intramuscularly injected with E2, while control gilts received corn oil. The ovaries were then collected and processed for double-labelling immunofluorescence. After E2 administration, the total number of fibers IR to VAChT, nNOS and VIP decreased significantly. The numbers of VAChT-, nNOS- and VIP-IR fibers within the ground plexus were significantly lower, while they were significantly higher around small or medium tertiary follicles. In the E2-affected ovaries, the numbers of nNOS- and VIP-IR fibers were significantly higher near secondary follicles and VAChT-IR in the vicinity of medullar blood vessels. In turn, around the latter structures there were significantly lowered populations of nNOS- and VIP-IR nerve fibers. These results suggest that the elevated E2 levels that occur during pathological states may affect the cholinergic innervation pattern of ovaries and their function(s).
Assuntos
Estradiol/farmacologia , Ovário/efeitos dos fármacos , Ovário/inervação , Sistema Nervoso Parassimpático/efeitos dos fármacos , Animais , Feminino , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Óxido Nítrico Sintase Tipo I/metabolismo , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/inervação , Somatostatina/metabolismo , Sus scrofa , Suínos , Peptídeo Intestinal Vasoativo/metabolismo , Proteínas Vesiculares de Transporte de Acetilcolina/metabolismoRESUMO
The effects of estrogen replacement therapy (ORT) on white matter and the myelin sheath ultrastructure in the white matter of middle-aged ovariectomized (OVX) rats were investigated in this study. Middle-aged rats were ovariectomized and divided into a placebo replacement (OVX + O) group and an estrogen replacement (OVX + E) group. Then, the Morris water maze, electron microscope techniques, and stereological methods were used to investigate the effects of ORT on spatial learning capacity, white matter volume and the myelin sheath ultrastructure in the white matter. We found that the spatial learning capacity of the OVX + E rats was significantly improved compared with that of the OVX + O rats. When compared with that of OVX + O rats, the total volume of the myelin sheaths in the white matter of the OVX + E rats was significantly increased by 27%, and the difference between the outer perimeter and inner perimeter of the myelin sheaths of the white matter in the OVX + E rats increased significantly by 12.6%. The myelinated fibers with mean diameters of 1.2-1.4 µm were significantly longer (46.1%) in the OVX + E rats; the difference between the mean diameter of myelinated fibers and the mean diameter of axons (0-0.4 µm) was significantly increased by 21.6% in the OVX + E rats. These results suggested that ORT had positive protective effects on the spatial learning ability and on the myelin sheath ultrastructure in the white matter of middle-aged OVX rats.
Assuntos
Estradiol/farmacologia , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/ultraestrutura , Fibras Nervosas Mielinizadas/ultraestrutura , Substância Branca/efeitos dos fármacos , Substância Branca/ultraestrutura , Animais , Terapia de Reposição de Estrogênios , Estrogênios/sangue , Feminino , Aprendizagem em Labirinto/efeitos dos fármacos , Menopausa , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Ovariectomia/efeitos adversos , Ratos , Ratos Sprague-Dawley , Estatísticas não ParamétricasRESUMO
OBJECTIVE: Traumatic spinal cord injury (SCI) causes apoptosis of myelin-forming oligodendrocytes (OLs) and demyelination of surviving axons, resulting in conduction failure. Remyelination of surviving denuded axons provides a promising therapeutic target for spinal cord repair. While cell transplantation has demonstrated efficacy in promoting remyelination and functional recovery, the lack of ideal cell sources presents a major obstacle to clinical application. The adult spinal cord contains oligodendrocyte precursor cells and multipotent neural stem/progenitor cells that have the capacity to differentiate into mature, myelinating OLs. However, endogenous oligodendrogenesis and remyelination processes are limited by the upregulation of remyelination-inhibitory molecules in the post-injury microenvironment. Multiple growth factors/molecules have been shown to promote OL differentiation and myelination. APPROACH: In this study we screened these therapeutics and found that 3, 3', 5-triiodothyronine (T3) is the most effective in promoting oligodendrogenesis and OL maturation in vitro. However, systemic administration of T3 to achieve therapeutic doses in the injured spinal cord is likely to induce hyperthyroidism, resulting in serious side effects. MAIN RESULTS: In this study we developed a novel hydrogel-based drug delivery system for local delivery of T3 to the injury site without eliciting systemic toxicity. SIGNIFICANCE: Using a clinically relevant cervical contusion injury model, we demonstrate that local delivery of T3 at doses comparable to safe human doses promoted new mature OL formation and myelination after SCI.
Assuntos
Implantes de Medicamento/administração & dosagem , Injeções Espinhais/métodos , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Regeneração Nervosa/efeitos dos fármacos , Oligodendroglia/efeitos dos fármacos , Traumatismos da Medula Espinal/fisiopatologia , Tri-Iodotironina/administração & dosagem , Animais , Diferenciação Celular/efeitos dos fármacos , Feminino , Hidrogéis/química , Fibras Nervosas Mielinizadas/patologia , Regeneração Nervosa/fisiologia , Oligodendroglia/patologia , Ratos , Ratos Sprague-Dawley , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/patologia , Resultado do TratamentoRESUMO
Estrogen induces oligodendrocyte remyelination in response to demyelination in the central nervous system. Our objective was to determine the effects of 17ß-estradiol (E2) on Schwann cell function and peripheral nerve remyelination after injury. Adult male C57BL/6J mice were used to prepare the sciatic nerve transection injury model and were randomly categorized into control and E2 groups. To study myelination in vitro, dorsal root ganglion (DRG) explant culture was prepared using 13.5-day-old mouse embryos. Primary Schwann cells were isolated from the sciatic nerves of 1- to 3-day-old Sprague-Dawley rats. Immunostaining for myelin basic protein (MBP) expression and toluidine blue staining for myelin sheaths demonstrated that E2 treatment accelerates early remyelination in the "nerve bridge" region between the proximal and distal stumps of the transection injury site in the mouse sciatic nerve. The 5-bromo-2'-deoxyuridine incorporation assay revealed that E2 promotes Schwann cell proliferation in the bridge region and in the primary culture, which is blocked using AKT inhibitor MK2206. The in vitro myelination in the DRG explant culture determined showed that the MBP expression in the E2-treated group is higher than that in the control group. These results show that E2 promotes Schwann cell proliferation and myelination depending on AKT activation.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Estradiol/farmacologia , Estradiol/uso terapêutico , Traumatismos dos Nervos Periféricos/tratamento farmacológico , Células de Schwann/efeitos dos fármacos , Animais , Células Cultivadas , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/fisiopatologia , Ratos , Ratos Sprague-DawleyRESUMO
Oxaliplatin-induced peripheral neuropathy (OIPN) occurs at extraordinarily high frequency, but no effective treatment for this disorder has been established. Goshajinkigan (GJG), a traditional Japanese medicine known as Kampo, is known to reduce OIPN in both basic and clinical studies. However, its molecular mechanisms remain largely unknown. Here, we elucidate the mechanisms underlying the therapeutic effects of GJG against OIPN and the therapeutic benefits of combining GJG with bushi, a herbal medicine derived from the processed Aconiti tuber. Oxaliplatin (4 mg/kg) was injected into mice twice a week for up to 4 and 3 weeks, respectively. OIPN was assessed using pain behavioral tests, such as those testing cold hypersensitivity, thermal hyperalgesia, and mechanical allodynia, as well as a reduction of the current perception threshold (CPT). GJG (0.3 or 1 g/kg) and bushi (0.1 or 0.3 g/kg) were orally administered 5 times a week for 4 weeks. Behavioral analysis was performed 24 h after the final dose. Oxaliplatin induced cold hypersensitivity and mechanical allodynia but not thermal hyperalgesia and reduced CPT of Aδ- and Aß-fibers but not C-fibers. All these effects were counteracted by GJG. Bushi, an ingredient of GJG that shows analgesic effect, reduced oxaliplatin-induced cold hypersensitivity but had no effect on oxaliplatin-induced mechanical allodynia. However, bushi significantly accentuated the effects of GJG when co-administered with GJG. GJG reduces OIPN by counteracting the sensitization of Aδ- and Aß-fibers and shows analgesic effects against cold hypersensitivity and mechanical allodynia. These effects are potentiated by bushi. The combination of GJG with bushi has high potential for preventing OIPN.
Assuntos
Medicamentos de Ervas Chinesas/administração & dosagem , Compostos Organoplatínicos/efeitos adversos , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/tratamento farmacológico , Extratos Vegetais/administração & dosagem , Animais , Antineoplásicos/efeitos adversos , Síndromes Periódicas Associadas à Criopirina/induzido quimicamente , Síndromes Periódicas Associadas à Criopirina/tratamento farmacológico , Modelos Animais de Doenças , Quimioterapia Combinada , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Masculino , Camundongos , Camundongos Endogâmicos ICR , Fibras Nervosas Mielinizadas/efeitos dos fármacos , OxaliplatinaRESUMO
Multiple sclerosis (MS) is an autoimmune neurodegenerative disease that involves activation of T cells, microglia, and astrocytes. There is a clear unmet medical need for MS, as current therapies reduce the relapse rate, but are unable to prevent the neurological deterioration. Leukemia inhibitory factor (LIF) is a proinflammatory cytokine that can also positively modulate the immune response, by inducing the inhibition of myelin-reactive TH17 differentiation, and by promoting oligodendrocyte-mediated myelination. The aim of this project was to find central nervous system (CNS)-permeable and orally available small molecules that upregulate production of endogenous LIF. We describe here the development of a phenotypic assay and screening of 1.7 million compounds to identify LIF enhancers using U87 MG cells. Five chemically tractable series of compounds and a few singletons were selected for further progression. Some of them were also active in a different LIF-expressing cell line and in primary rat astrocytes. Although further studies would be required to deconvolute the targets involved in LIF induction and to confirm activity of hits in more disease-relevant assays, our results have demonstrated the potential of the phenotypic approach to identify specific and chemically tractable small molecules that trigger the production of LIF in relevant cell lines.
Assuntos
Elementos Facilitadores Genéticos/genética , Fator Inibidor de Leucemia/genética , Esclerose Múltipla/tratamento farmacológico , Bibliotecas de Moléculas Pequenas/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Sistema Nervoso Central/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Imunidade Celular/efeitos dos fármacos , Esclerose Múltipla/genética , Esclerose Múltipla/patologia , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Mielinizadas/metabolismo , Oligodendroglia/efeitos dos fármacos , Ratos , Bibliotecas de Moléculas Pequenas/isolamento & purificação , Linfócitos T/efeitos dos fármacos , Células Th17/efeitos dos fármacosRESUMO
BACKGROUND: Sensory nerves innervating the airways play an important role in regulating various cardiopulmonary functions, maintaining homeostasis under healthy conditions and contributing to pathophysiology in disease states. Hypo-osmotic solutions elicit sensory reflexes, including cough, and are a potent stimulus for airway narrowing in asthmatic patients, but the mechanisms involved are not known. Transient receptor potential cation channel, subfamily V, member 4 (TRPV4) is widely expressed in the respiratory tract, but its role as a peripheral nociceptor has not been explored. OBJECTIVE: We hypothesized that TRPV4 is expressed on airway afferents and is a key osmosensor initiating reflex events in the lung. METHODS: We used guinea pig primary cells, tissue bioassay, in vivo electrophysiology, and a guinea pig conscious cough model to investigate a role for TRPV4 in mediating sensory nerve activation in vagal afferents and the possible downstream signaling mechanisms. Human vagus nerve was used to confirm key observations in animal tissues. RESULTS: Here we show TRPV4-induced activation of guinea pig airway-specific primary nodose ganglion cells. TRPV4 ligands and hypo-osmotic solutions caused depolarization of murine, guinea pig, and human vagus and firing of Aδ-fibers (not C-fibers), which was inhibited by TRPV4 and P2X3 receptor antagonists. Both antagonists blocked TRPV4-induced cough. CONCLUSION: This study identifies the TRPV4-ATP-P2X3 interaction as a key osmosensing pathway involved in airway sensory nerve reflexes. The absence of TRPV4-ATP-mediated effects on C-fibers indicates a distinct neurobiology for this ion channel and implicates TRPV4 as a novel therapeutic target for neuronal hyperresponsiveness in the airways and symptoms, such as cough.
Assuntos
Trifosfato de Adenosina/metabolismo , Neurônios Aferentes/metabolismo , Sistema Respiratório/inervação , Sistema Respiratório/metabolismo , Canais de Cátion TRPV/metabolismo , Animais , Sinalização do Cálcio , Tosse , Relação Dose-Resposta a Droga , Cobaias , Masculino , Camundongos , Camundongos Knockout , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Mielinizadas/metabolismo , Neurônios Aferentes/efeitos dos fármacos , Gânglio Nodoso/citologia , Gânglio Nodoso/efeitos dos fármacos , Gânglio Nodoso/metabolismo , Antagonistas do Receptor Purinérgico P2X/farmacologia , Canais de Cátion TRPV/agonistas , Nervo Vago/efeitos dos fármacos , Nervo Vago/fisiologiaRESUMO
Oxaliplatin, a widely used chemotherapeutic agent, induces peripheral neuropathy that manifests itself as two distinct phases: acute cold hyperesthesia and chronic peripheral hypoesthesia/dysesthesia. The latter is a serious dose-limiting side effect that can often lead to withdrawal of treatment. We have developed a rat model expressing both phases and used the model to investigate the action of goshajinkigan (GJG), a traditional Japanese herbal medicine, which was reported to ameliorate oxaliplatin-induced neuropathy in a placebo-controlled double-blind randomized phase II study. In this study, neuropathy was induced by injection of oxaliplatin twice weekly for 8 wks. The maximum level of cold hyperesthesia was observed at 4 wks with heat hypoesthesia developing later. Microscopy studies revealed atrophy of axons of myelinated sciatic nerve fibers in oxaliplatin-treated rats at 8 wks. Co-administration of GJG ameliorated both abnormal sensations as well as histological damage to the sciatic nerve. A pharmacokinetic study revealed numerous neuroprotective components of GJG that are rapidly absorbed into the blood. GJG and some of its components attenuated the generation of oxaliplatin-induced reactive oxygen species, which is a possible mechanism of oxaliplatin-induced neurotoxicity. The present study provides a useful animal model for oxaliplatin-induced neurotoxicity as well as a promising prophylactic agent.
Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Hipestesia/induzido quimicamente , Hipestesia/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Compostos Organoplatínicos/efeitos adversos , Animais , Antineoplásicos/farmacologia , Atrofia/induzido quimicamente , Atrofia/tratamento farmacológico , Axônios/efeitos dos fármacos , Modelos Animais de Doenças , Gânglios Espinais/efeitos dos fármacos , Medicina Herbária/métodos , Masculino , Medicina Tradicional do Leste Asiático/métodos , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Síndromes Neurotóxicas/tratamento farmacológico , Oxaliplatina , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/tratamento farmacológico , Fitoterapia/métodos , Ratos , Ratos Sprague-DawleyRESUMO
Mechanical allodynia, induced by normally innocuous low-threshold mechanical stimulation, represents a cardinal feature of neuropathic pain. Blockade or ablation of high-threshold, small-diameter unmyelinated group C nerve fibers (C-fibers) has limited effects on mechanical allodynia. Although large, myelinated group A fibers, in particular Aß-fibers, have previously been implicated in mechanical allodynia, an A-fiber-selective pharmacological blocker is still lacking. Here we report a new method for targeted silencing of A-fibers in neuropathic pain. We found that Toll-like receptor 5 (TLR5) is co-expressed with neurofilament-200 in large-diameter A-fiber neurons in the dorsal root ganglion (DRG). Activation of TLR5 with its ligand flagellin results in neuronal entry of the membrane-impermeable lidocaine derivative QX-314, leading to TLR5-dependent blockade of sodium currents, predominantly in A-fiber neurons of mouse DRGs. Intraplantar co-application of flagellin and QX-314 (flagellin/QX-314) dose-dependently suppresses mechanical allodynia after chemotherapy, nerve injury, and diabetic neuropathy, but this blockade is abrogated in Tlr5-deficient mice. In vivo electrophysiology demonstrated that co-application of flagellin/QX-314 selectively suppressed Aß-fiber conduction in naive and chemotherapy-treated mice. TLR5-mediated Aß-fiber blockade, but not capsaicin-mediated C-fiber blockade, also reduced chemotherapy-induced ongoing pain without impairing motor function. Finally, flagellin/QX-314 co-application suppressed sodium currents in large-diameter human DRG neurons. Thus, our findings provide a new tool for targeted silencing of Aß-fibers and neuropathic pain treatment.
Assuntos
Anestésicos Locais/farmacologia , Flagelina/farmacologia , Gânglios Espinais/efeitos dos fármacos , Hiperalgesia/genética , Lidocaína/análogos & derivados , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Neuralgia/genética , Neurônios/efeitos dos fármacos , Receptor 5 Toll-Like/genética , Adulto , Idoso , Animais , Antineoplásicos/toxicidade , Capsaicina/farmacologia , Neuropatias Diabéticas/complicações , Feminino , Gânglios Espinais/citologia , Gânglios Espinais/metabolismo , Humanos , Hiperalgesia/etiologia , Hiperalgesia/metabolismo , Lidocaína/farmacologia , Masculino , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Amielínicas/efeitos dos fármacos , Neuralgia/etiologia , Neuralgia/metabolismo , Proteínas de Neurofilamentos/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Paclitaxel/toxicidade , Traumatismos dos Nervos Periféricos/complicações , Fármacos do Sistema Sensorial/farmacologiaRESUMO
This study aimed to investigate the mechanism of nimodipine-mediated neural repair after facial nerve crush injury in rats. Adult Sprague-Dawley rats were divided into three groups: healthy controls, surgery alone, and surgery plus nimodipine. A facial nerve crush injury model was constructed. Immediately after surgery, the rats in the surgery plus nimodipine group were administered nimodipine, 6 mg/kg/day, for a variable numbers of days. The animals underwent electromyography (EMG) before surgery and at 3, 10, or 20 days after surgery. After sacrifice, nerve samples were stained with hematoxylin and eosin (H&E) and luxol fast blue. The EMG at 20 days revealed an apparent recovery of eletroconductivity, with the surgery plus nimodipine group having a higher amplitude and shorter latency time than the surgery only group. H&E staining showed that at 20 days, the rats treated with nimodipine had an obvious recovery of myelination and reduction in the number of infiltrating cells, suggesting less inflammation, compared with the rats in the surgery only group. Luxol fast blue staining was relatively even in the surgery plus nimodipine group, indicating a protective effect against injury-induced demyelination. Staining for S100 calcium-binding protein B (S-100ß) was not evident in the surgery alone group, but was evident in the surgery plus nimodipine group, indicating that nimodipine reversed the damage of the crush injury. After a facial nerve crush injury, treatment with nimodipine for 20 days reduced the nerve injury by mediating remyelination by Schwann cells. The protective effect of nimodipine may include a reduction of inflammation and an increase in calcium-binding S-100ß protein.
Assuntos
Traumatismos do Nervo Facial/tratamento farmacológico , Traumatismos do Nervo Facial/fisiopatologia , Compressão Nervosa/métodos , Fibras Nervosas Mielinizadas/fisiologia , Nimodipina/uso terapêutico , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/uso terapêutico , Proteínas de Ligação ao Cálcio/fisiologia , Eletromiografia/métodos , Masculino , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Nimodipina/farmacologia , Ratos , Ratos Sprague-DawleyRESUMO
PURPOSE: The aim of this study was to evaluate the relative effectiveness of stellate ganglion blockade (SGB) versus xenon light irradiation (XLI) for the treatment of neurosensory deficits resulting from orthognathic surgery as determined by a comparison of prospective measurements of electrical current perception thresholds (CPTs) and ranged CPTs (R-CPTs). MATERIALS AND METHODS: CPT and R-CPT in the mental foramen area were measured during electrical stimulation at 98 different sites on the body in patients who had undergone orthognathic surgery. After surgery, patients were assigned to the SGB group or the XLI group. CPT and R-CPT of the 2 groups were measured at stimulation frequencies of 2,000, 250, and 5 Hz before surgery, 1 week after surgery, and after 10 treatment sessions. Furthermore, the influence of surgical factors, such as genioplasty and a surgically exposed inferior alveolar nerve (IAN), was examined in the 2 groups. RESULTS: Patients' CPT and R-CPT values indicated a considerable amount of sensory disturbance in most cases after surgery. The change in magnitude of all CPT and R-CPT values for the SGB group decreased considerably compared with that for the XLI group after treatment. There was no correlation between CPT or R-CPT values and surgical factors (eg, genioplasty and exposure of the IAN). CONCLUSION: SGB of the IAN could be an effective method for treating neurosensory deficits after orthognathic surgery on the IAN.
Assuntos
Lasers de Gás/uso terapêutico , Terapia com Luz de Baixa Intensidade/métodos , Bloqueio Nervoso/métodos , Procedimentos Cirúrgicos Ortognáticos/efeitos adversos , Complicações Pós-Operatórias/terapia , Distúrbios Somatossensoriais/terapia , Gânglio Estrelado/efeitos dos fármacos , Adolescente , Adulto , Anestésicos Locais/administração & dosagem , Estimulação Elétrica/métodos , Feminino , Seguimentos , Mentoplastia/efeitos adversos , Humanos , Masculino , Nervo Mandibular/efeitos dos fármacos , Nervo Mandibular/fisiopatologia , Nervo Mandibular/efeitos da radiação , Maxila/cirurgia , Mepivacaína/administração & dosagem , Pessoa de Meia-Idade , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Mielinizadas/fisiologia , Fibras Nervosas Mielinizadas/efeitos da radiação , Osteotomia de Le Fort/efeitos adversos , Osteotomia Sagital do Ramo Mandibular/efeitos adversos , Complicações Pós-Operatórias/radioterapia , Estudos Prospectivos , Limiar Sensorial/fisiologia , Distúrbios Somatossensoriais/radioterapia , Adulto JovemAssuntos
Barorreflexo/fisiologia , Estradiol/farmacologia , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Neurônios Aferentes/efeitos dos fármacos , Pressorreceptores/efeitos dos fármacos , Receptores Acoplados a Proteínas G/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Barorreflexo/efeitos dos fármacos , Modelos Animais de Doenças , Estrogênios/farmacologia , Feminino , Neurônios Aferentes/metabolismo , Ovariectomia , Pressorreceptores/metabolismo , Pressorreceptores/fisiopatologia , RatosRESUMO
It is all known that dedifferentiated Schwann cells (SCs) play an important role in neural regeneration, and Notch signaling has complex and extensive regulatory functions in dedifferentiated SCs. So studies have focused on how to improve peripheral nerve repair by regulating proliferation and dedifferentiation in SCs with Notch signaling meloculars.We have found SCs can be activated when adding Recombinant rat jagged1/FC chimera (an activator of the Notch signaling system) in vivo. Compared with that of the control groups, at 4 weeks post-surgery nerve regeneration and functional rehabilitation in the Recombinant rat jagged1/FC chimera group were advanced significantly, and the expression of neurotrophic factors in the regenerated nerves was elevated largely. These results indicated that SCs activated by Notch signaling could promote nerve repair effectively in the early regenerative stage, suggesting the possible clinical application for the treatment of peripheral nerve defects.
Assuntos
Proteínas de Ligação ao Cálcio/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Proteínas de Membrana/farmacologia , Regeneração Nervosa/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/metabolismo , Receptor Notch1/metabolismo , Células de Schwann/efeitos dos fármacos , Nervo Isquiático/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Regulação da Expressão Gênica , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteína Jagged-1 , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Mielinizadas/metabolismo , Fator de Crescimento Neural/genética , Fator de Crescimento Neural/metabolismo , Regeneração Nervosa/genética , Traumatismos dos Nervos Periféricos/tratamento farmacológico , Traumatismos dos Nervos Periféricos/genética , Traumatismos dos Nervos Periféricos/patologia , Ratos , Ratos Sprague-Dawley , Receptor Notch1/agonistas , Receptor Notch1/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Células de Schwann/citologia , Células de Schwann/metabolismo , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/lesões , Proteínas Serrate-Jagged , Transdução de Sinais , Fatores de Transcrição HES-1RESUMO
Roles of vitamin D on the immune and nervous systems are increasingly recognized. Two previous studies demonstrated that ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) induced functional recovery and increased myelination in a rat model of peroneal nerve transection. The current report assessed whether cholecalciferol was efficient in repairing transected rabbit facial nerves. Animals were randomized into two groups of rabbits with an unilateral facial nerve surgery: the vitamin D group included animals receiving a weekly oral bolus of vitamin D3 (200 IU/kg/day), from day 1 post-surgery; the control group included animals receiving a weekly oral bolus of vehicle (triglycerides). Contralateral unsectioned facial nerves from all experimental animals were used as controls for the histological study. The facial functional index was measured every week while the inner diameter of myelin sheath and the G ratio were quantified at the end of the 3 month experiment. The current report indicates that cholecalciferol significantly increases functional recovery and myelination, after 12 weeks of treatment. To the best of our knowledge, this is the first study investigating the therapeutic benefit of vitamin D supplementation in an animal model of facial paralysis. It paves further the way for clinical trials based on the administration of this steroid in individuals with injured facial nerves.
Assuntos
Colecalciferol/farmacologia , Suplementos Nutricionais , Traumatismos do Nervo Facial/tratamento farmacológico , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Recuperação de Função Fisiológica/fisiologia , Animais , Modelos Animais de Doenças , Traumatismos do Nervo Facial/fisiopatologia , Masculino , Coelhos , Vitaminas/farmacologiaRESUMO
Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited sensory and motor peripheral neuropathy. It is caused by PMP22 overexpression which leads to defects of peripheral myelination, loss of long axons, and progressive impairment then disability. There is no treatment available despite observations that monotherapeutic interventions slow progression in rodent models. We thus hypothesized that a polytherapeutic approach using several drugs, previously approved for other diseases, could be beneficial by simultaneously targeting PMP22 and pathways important for myelination and axonal integrity. A combination of drugs for CMT1A polytherapy was chosen from a group of authorised drugs for unrelated diseases using a systems biology approach, followed by pharmacological safety considerations. Testing and proof of synergism of these drugs were performed in a co-culture model of DRG neurons and Schwann cells derived from a Pmp22 transgenic rat model of CMT1A. Their ability to lower Pmp22 mRNA in Schwann cells relative to house-keeping genes or to a second myelin transcript (Mpz) was assessed in a clonal cell line expressing these genes. Finally in vivo efficacy of the combination was tested in two models: CMT1A transgenic rats, and mice that recover from a nerve crush injury, a model to assess neuroprotection and regeneration. Combination of (RS)-baclofen, naltrexone hydrochloride and D-sorbitol, termed PXT3003, improved myelination in the Pmp22 transgenic co-culture cellular model, and moderately down-regulated Pmp22 mRNA expression in Schwannoma cells. In both in vitro systems, the combination of drugs was revealed to possess synergistic effects, which provided the rationale for in vivo clinical testing of rodent models. In Pmp22 transgenic CMT1A rats, PXT3003 down-regulated the Pmp22 to Mpz mRNA ratio, improved myelination of small fibres, increased nerve conduction and ameliorated the clinical phenotype. PXT3003 also improved axonal regeneration and remyelination in the murine nerve crush model. Based on these observations in preclinical models, a clinical trial of PTX3003 in CMT1A, a neglected orphan disease, is warranted. If the efficacy of PTX3003 is confirmed, rational polytherapy based on novel combinations of existing non-toxic drugs with pleiotropic effects may represent a promising approach for rapid drug development.