RESUMEN
BACKGROUND: Intermittent hypoxia induces increased ventilatory responses in a 5-HT-dependent manner. This study aimed to explore that effect of raphe magnus serotonin 1A receptor (5-HT1A) receptor on the increased ventilatory responses induced by intermittent hypoxia. METHODS: Stereotaxic surgery was performed in adult male rats, and acute and chronic intermittent hypoxia models were established after recovery from surgery. The experimental group received microinjections of 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) into the raphe magnus nucleus (RMg). Meanwhile, the control group received microinjections of artificial cerebrospinal fluid instead of 8-OH-DPAT. Ventilatory responses were compared among the different groups of oxygen status. 5-HT expressions in the RMg region were assessed by immunohistochemistry after chronic intermittent hypoxia. RESULTS: Compared with the normoxia group, the acute intermittent hypoxia group exhibited higher ventilatory responses (e.g., shorter inspiratory time and higher tidal volume, frequency of breathing, minute ventilation, and mean inspiratory flow) (P < 0.05). 8-OH-DPAT microinjection partly weakened these changes in the acute intermittent hypoxia group. Further, compared with the acute intermittent hypoxia group, rats in chronic intermittent hypoxia group exhibited higher measures of ventilatory responses after 1 day of intermittent hypoxia (P < 0.05). These effects peaked after 3 days of intermittent hypoxia treatment and then decreased gradually. Moreover, these changes were diminished in the experimental group. 5-HT expression in the RMg region increased after chronic intermittent hypoxia, which was consistent with the changing trend of ventilatory responses. While activation of the 5-HT1A receptor in the RMg region alleviated this phenomenon. CONCLUSIONS: The results indicate that RMg 5-HT1A receptor, via changing the expression level of 5-HT in the RMg region, is involved in the modulation of the increased ventilatory responses induced by intermittent hypoxia.
Asunto(s)
Hipoxia/metabolismo , Núcleo Magno del Rafe/metabolismo , Ventilación Pulmonar/efectos de los fármacos , Receptor de Serotonina 5-HT1A/metabolismo , Agonistas de Receptores de Serotonina/farmacología , Volumen de Ventilación Pulmonar/efectos de los fármacos , Animales , Modelos Animales de Enfermedad , Hipoxia/tratamiento farmacológico , Hipoxia/fisiopatología , Masculino , Núcleo Magno del Rafe/efectos de los fármacos , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: The pathogenesis of medication overuse headache (MOH) involves hyperexcitability of cortical and trigeminal neurons. Derangement of the brainstem modulating system, especially raphe nuclei may contribute to this hyperexcitability. The present study aimed to investigate the involvement of the nucleus raphe magnus (NRM) in the development of cortical and trigeminal hyperexcitability in a rat model of MOH. RESULTS: Chronic treatment with acetaminophen increased the frequency of cortical spreading depression (CSD) and the number of c-Fos-immunoreactive (Fos-IR) neurons in the trigeminal nucleus caudalis (TNC). In the control group, muscimol microinjected into the NRM increased significantly the frequency of CSD-evoked direct current shift and Fos-IR neurons in the TNC. This facilitating effect was not found in rats with chronic acetaminophen exposure. In a model of migraine induced by intravenous systemic infusion of nitroglycerin (NTG), rats with chronic exposure to acetaminophen exhibited significantly more frequent neuronal firing in the TNC and greater Fos-IR than those without the acetaminophen treatment. Muscimol microinjection increased neuronal firing in the TNC in control rats, but not in acetaminophen-treated rats. The number of Fos-IR cells in TNC was not changed significantly. CONCLUSION: Chronic exposure to acetaminophen alters the function of the NRM contributing to cortical hyperexcitability and facilitating trigeminal nociception.
Asunto(s)
Corteza Cerebral/fisiopatología , Cefaleas Secundarias/fisiopatología , Nocicepción/fisiología , Núcleo Magno del Rafe/fisiopatología , Núcleos del Trigémino/fisiopatología , Acetaminofén , Potenciales de Acción/efectos de los fármacos , Animales , Corteza Cerebral/efectos de los fármacos , Modelos Animales de Enfermedad , Masculino , Trastornos Migrañosos/etiología , Trastornos Migrañosos/fisiopatología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Nitroglicerina , Núcleo Magno del Rafe/efectos de los fármacos , Proteínas Proto-Oncogénicas c-fos/metabolismo , Distribución Aleatoria , Ratas Wistar , Núcleos del Trigémino/efectos de los fármacosRESUMEN
Restraint water-immersion stress (RWIS) consists of psychological and physical stimulation, and it has been utilized in the research of gastric mucosal damage. It has been shown by previous studies that the nucleus raphe magnus (NRM) is closely involved in the gastrointestinal function, but its functions on the stress-induced gastric mucosal injury (SGMI) have not been thoroughly elucidated to date. Consequently, in this research, we aim to measure the expression of astrocytic glial fibrillary acidic protein (GFAP), neuronal c-Fos, and phosphorylation extracellular signal regulated kinase 1/2 (p-ERK1/2) in the process of RWIS with immunohistochemistry and western blot methods. What is more, we detect the relation between astrocytes and neurons throughout the stress procedure and explore the regulation of the ERK1/2 signaling pathway on the activity of astrocytes and neurons after RWIS. The results indicated that all three proteins expression multiplied following peaked 3 h substantially. The SMGI, astrocyte and neuron activity were affected after the astrocytotoxin L-A-aminohexanedioic acid (L-AA) and c-fos antisense oligonucleotide (ASO) injections. After the injection of PD98059, the gastric mucosal injury, astrocyte and neuron activity significantly fell off. These results suggested that RWIS-induced activity of astrocytes and neurons in the NRM may play a significant part in gastric mucosa damage via the ERK1/2 signaling pathway.
Asunto(s)
Astrocitos/metabolismo , Mucosa Gástrica/fisiopatología , Sistema de Señalización de MAP Quinasas/fisiología , Neuronas/metabolismo , Núcleo Magno del Rafe/metabolismo , Animales , Flavonoides/farmacología , Mucosa Gástrica/patología , Proteína Ácida Fibrilar de la Glía/metabolismo , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Masculino , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Proteínas Proto-Oncogénicas c-fos/metabolismo , Ratas Wistar , Restricción Física/efectos adversos , Estrés Psicológico/fisiopatologíaRESUMEN
It has been established that the midbrain periaqueductal gray matter (PAG) and rostral ventro-medial medulla (RVM) are involved in the descending pain control system. The latter involves the midline nucleus raphe magnus (NRM) and adjacent reticular formation. These brain structures are is one of important parts of CNS circuit that controls nociceptive transmission at the level of spinal cord. Here we report that microinjection of commonly used non-steroidal anti-inflammatory drugs (NSAIDs), diclofenac, ketorolac, metamizol, and xefocam into the NRM produces strong antinociception which is mediated by the opioid mechanism. The experiments were carried out on experimental and control (saline) white albino male rats. Animals were implanted with a guide cannula in the NRM and tested for antinociception following microinjection of NSAIDs into the NRM in the tail flick (TF) and hot plate (HP) tests. The analysis of variance (ANOVA) with post-hoc Tukey-Kramer multiple comparison tests were used for statistical evaluation. The obtained data show that microinjection of these NSAIDs into the NRM produced antinociception as revealed by a latency increase in the tail-flick (TF) and hot plate (HP) latencies compared to the saline control microinjected into the same nucleus. Furthermore, we definitely showed that pre-treatment with opioid antagonist naloxone in the NRM diminishes NSAID-induced antinociception expressing in significant decrease in TF and HP latencies (P<0.001). The present findings support the concept that antinociceptive effects of NSAIDs are mediated via an endogenous opioid system possibly involving the descending pain modulatory circuit.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Naloxona/farmacología , Antagonistas de Narcóticos/farmacología , Nocicepción/efectos de los fármacos , Núcleo Magno del Rafe/efectos de los fármacos , Péptidos Opioides/metabolismo , Animales , Diclofenaco/farmacología , Dipirona/farmacología , Ketorolaco/farmacología , Masculino , Microinyecciones , Núcleo Magno del Rafe/fisiología , Piroxicam/análogos & derivados , Piroxicam/farmacología , Ratas , Tiempo de ReacciónRESUMEN
Our previous study demonstrated that persistent pain can epigenetically suppress the transcription of Gad2 [encoding glutamic acid decarboxylase 65 (GAD65)] and consequently impair the inhibitory function of GABAergic synapses in central pain-modulating neurons. This contributes to the development of persistent pain sensitization. Histone deacetylase (HDAC) inhibitors increased GAD65 activity considerably, restored GABA synaptic function, and rendered sensitized pain behavior less pronounced. However, the molecular mechanisms by which HDAC regulates GABAergic transmission through GAD65 under pain conditions are unknown. This work showed that HDAC inhibitor-induced increases in colocalization of GAD65 and synaptic protein synapsin I on the presynaptic axon terminals of the nucleus raphe magnus (NRM) were blocked by a TrkB receptor antagonist K252a [(9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid methyl ester], indicating that BDNF-TrkB signaling may be required in GAD65 modulation of GABA synaptic function. At the brain-derived neurotrophic factor (BDNF) promoter, HDAC inhibitors induced significant increases in H3 hyperacetylation, consistent with the increase in BDNF mRNA and total proteins. Although exogenous BDNF facilitated GABA miniature inhibitory postsynaptic currents and GAD65 accumulation in NRM neuronal synapses in normal rats, it failed to do so in animals subjected to persistent inflammation. In addition, blockade of the TrkB receptor with K252a has no effect on miniature inhibitory postsynaptic currents and synaptic GAD65 accumulation under normal conditions. In addition, the analgesic effects of HDAC inhibitors on behavior were blocked by NRM infusion of K252a. These findings suggest that BDNF-TrkB signaling is required for drugs that reverse the epigenetic effects of chronic pain at the gene level, such as HDAC inhibitors.
Asunto(s)
Analgésicos/farmacología , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Inhibidores de Histona Desacetilasas/farmacología , Núcleo Magno del Rafe/efectos de los fármacos , Dolor/metabolismo , Analgésicos/uso terapéutico , Animales , Factor Neurotrófico Derivado del Encéfalo/genética , Carbazoles/farmacología , Glutamato Descarboxilasa/metabolismo , Inhibidores de Histona Desacetilasas/uso terapéutico , Ácidos Hidroxámicos/farmacología , Alcaloides Indólicos/farmacología , Inflamación/metabolismo , Masculino , Núcleo Magno del Rafe/metabolismo , Dolor/tratamiento farmacológico , Dolor/fisiopatología , Regiones Promotoras Genéticas , Ratas Wistar , Receptor trkB/antagonistas & inhibidores , Receptor trkB/metabolismo , Transducción de Señal , Sinapsis/metabolismo , Sinapsinas/metabolismo , Vorinostat , Ácido gamma-Aminobutírico/metabolismoRESUMEN
The enhanced AMPA receptor phosphorylation at GluA1 serine 831 sites in the central pain-modulating system plays a pivotal role in descending pain facilitation after inflammation, but the underlying mechanisms remain unclear. We show here that, in the rat brain stem, in the nucleus raphe magnus, which is a critical relay in the descending pain-modulating system of the brain, persistent inflammatory pain induced by complete Freund adjuvant (CFA) can enhance AMPA receptor-mediated excitatory postsynaptic currents and the GluA2-lacking AMPA receptor-mediated rectification index. Western blot analysis showed an increase in GluA1 phosphorylation at Ser-831 but not at Ser-845. This was accompanied by an increase in distribution of the synaptic GluA1 subunit. In parallel, the level of histone H3 acetylation at bdnf gene promoter regions was reduced significantly 3 days after CFA injection, as indicated by ChIP assays. This was correlated with an increase in BDNF mRNA levels and BDNF protein levels. Sequestering endogenous extracellular BDNF with TrkB-IgG in the nucleus raphe magnus decreased AMPA receptor-mediated synaptic transmission and GluA1 phosphorylation at Ser-831 3 days after CFA injection. Under the same conditions, blockade of TrkB receptor functions, phospholipase C, or PKC impaired GluA1 phosphorylation at Ser-831 and decreased excitatory postsynaptic currents mediated by GluA2-lacking AMPA receptors. Taken together, these results suggest that epigenetic up-regulation of BDNF by peripheral inflammation induces GluR1 phosphorylation at Ser-831 sites through activation of the phospholipase C-PKC signaling cascade, leading to the trafficking of GluA1 to pain-modulating neuronal synapses.
Asunto(s)
Factor Neurotrófico Derivado del Encéfalo/fisiología , Inflamación/fisiopatología , Núcleo Magno del Rafe/fisiopatología , Dolor/fisiopatología , Receptores AMPA/fisiología , Animales , Factor Neurotrófico Derivado del Encéfalo/genética , Epigénesis Genética , Potenciales Postsinápticos Excitadores , Inflamación/genética , Masculino , Dolor/genética , Regiones Promotoras Genéticas , Proteína Quinasa C/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptor trkB/metabolismo , Receptores AMPA/química , Transducción de Señal , Transmisión Sináptica , Fosfolipasas de Tipo C/metabolismo , Regulación hacia ArribaRESUMEN
Catalepsy usually is caused by imbalance of dopamine (DA) and serotonin (5-HT) systems of brain. The aim of our work was to verify if this imbalance plays an important role in the mechanism of hereditary catalepsy in mice. Maintenance of DA, 5-HT and their main metabolites--5-hydroxyindoleacetic acid, 3,4-dihydroxyphenylacetic acid, homovanilic acid was determined in cortex, hypothalamus, hippocampus, striatum, substantia nigra and nuclei raphes in catalepsy-resistant AKR/J mice strain and catalepsy-prone CBA/LacJ mice strain and recombinant mice AKR/J.CBA-D13Mit76 (D13) strain. The latest strain was selected by transferring of a fragment of the chromosome 13 from CBA/LacJ carrying the main gene of hereditary catalepsy to AKR/J genome. There were no interstrain differences in concentration of biogenic amines and their metabolites in all brain regions. As a result of our work the hypothesis about the important role of 5-HT and/or DA systems of brain in the mechanism of hereditary catalepsy in mice was denied.
Asunto(s)
Ácido 3,4-Dihidroxifenilacético/metabolismo , Catalepsia/metabolismo , Dopamina/metabolismo , Ácido Homovanílico/metabolismo , Ácido Hidroxiindolacético/metabolismo , Serotonina/metabolismo , Animales , Catalepsia/genética , Catalepsia/fisiopatología , Corteza Cerebral/metabolismo , Corteza Cerebral/fisiopatología , Cuerpo Estriado/metabolismo , Cuerpo Estriado/fisiopatología , Cruzamientos Genéticos , Predisposición Genética a la Enfermedad , Hipocampo/metabolismo , Hipocampo/fisiopatología , Hipotálamo/metabolismo , Hipotálamo/fisiopatología , Masculino , Ratones Endogámicos AKR , Ratones Endogámicos CBA , Núcleo Accumbens/metabolismo , Núcleo Accumbens/fisiopatología , Núcleo Magno del Rafe/metabolismo , Núcleo Magno del Rafe/fisiopatología , Sustancia Negra/metabolismo , Sustancia Negra/fisiopatologíaRESUMEN
BACKGROUND: Nefopam is a centrally acting antinociceptive drug; however, the underlying mechanisms are not fully understood. This study investigated the supraspinal mechanisms of nefopam. METHODS: The effects of intraperitoneally administered nefopam were assessed in rats using the formalin test, and the mechanisms were investigated by intrathecal or intra-nucleus raphe magnus (NRM) pre-treatment with the serotonin (5-HT) receptor antagonist or 5-HT2 receptor antagonist. The change in extracellular 5-HT levels was measured by spinal cord microdialysis. RESULTS: Intraperitoneally administered nefopam showed antinociceptive effects in the rat formalin test, which were reversed by intrathecal pre-treatment with 5-HT receptor antagonist dihydroergocristine. Microdialysis study revealed that systemic nefopam significantly increased 5-HT level in the spinal dorsal horn. Pretreatment of cinanserin, a 5-HT2 receptor antagonist, into the NRM blocked the antinociceptive effects of intraperitoneally delivered nefopam. Direct injection of nefopam into the NRM mimicked the effects of systemic nefopam, and this effect was reversed by intra-NRM cinanserin pre-treatment. The increase in spinal level of 5-HT by systemic nefopam was attenuated by intra-NRM cinanserin pre-treatment. CONCLUSION: The antinociceptive effects of systemically administered nefopam are mediated by 5-HT2 receptors in the NRM, which recruit the descending serotonergic fibres to increase the release of 5-HT into the spinal dorsal horn. SIGNIFICANCE: This study revealed supraspinal mechanisms of nefopam-produced analgesia mediated by 5-HT2 receptors in the NRM recruiting the descending serotonergic fibres to increase the release of 5-HT into the spinal dorsal horn. These observations support a potential role for nefopam in multimodal analgesia based on its distinct mechanisms of action that are not shared by the other analgesics.
Asunto(s)
Nefopam , Serotonina , Ratas , Animales , Serotonina/farmacología , Nefopam/farmacología , Nefopam/uso terapéutico , Núcleo Magno del Rafe , Cinanserina/farmacología , Cinanserina/uso terapéutico , Dolor/tratamiento farmacológico , Analgésicos/farmacología , Analgésicos/uso terapéutico , Médula Espinal , Antagonistas de la Serotonina/farmacología , Asta Dorsal de la Médula EspinalRESUMEN
BACKGROUND: Pontine infarction is the major subtype of posterior circulation stroke, and diabetes is more common in pontine infarction patients than in anterior circulation stroke patients. Whether the prevalence of diabetes remains homogenous within the posterior circulation stroke population is unclear. The present study is aimed at investigating the prevalence of diabetes in pontine infarction and comparing it to other subtypes of posterior circulation stroke. METHODS: We conducted a multicenter case-control study. Patients with posterior circulation stroke were screened. The subjects were divided into pontine infarction and nonpontine infarction groups. RESULTS: From November 1, 2018, to February 28, 2021, a total of 6145 stroke patients were screened and 2627 patients had posterior circulation strokes. After excluding cardioembolic stroke, as well as its other determined and undetermined causes, 1549 patients with 754 pontine infarctions were included in the analysis. The prevalence of diabetes in the pontine infarction group was higher than that in the nonpontine infarction group (42.7% vs. 31.4%, P < 0.05). After adjusting for confounding factors, diabetes was an independent risk factor for pontine infarction (OR 1.63, 95% CI 1.27-2.09, P < 0.05). For small vessel occlusion, diabetes was also more common in the pontine infarction group (43.2% vs. 30.0%, P < 0.05). Multivariate analysis also showed that diabetes was an independent risk factor for pontine infarction (OR 1.80, 95% CI 1.32-2.46, P < 0.05). CONCLUSION: In comparison with the nonpontine infarction subtype of posterior circulation stroke, patients with pontine infarction had a higher prevalence of diabetes, and diabetes was an independent risk factor for pontine infarction.
Asunto(s)
Diabetes Mellitus/etiología , Núcleo Magno del Rafe/anomalías , Accidente Cerebrovascular/complicaciones , Anciano , Estudios de Casos y Controles , China/epidemiología , Correlación de Datos , Diabetes Mellitus/epidemiología , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Núcleo Magno del Rafe/irrigación sanguínea , Núcleo Magno del Rafe/lesiones , Prevalencia , Factores de Riesgo , Accidente Cerebrovascular/epidemiologíaRESUMEN
The dorsal immobility response (DIR) and the tonic immobility response (TIR) are cutaneo-motor reflexes typically triggered when a prey is seized. The neurochemical basis of the DIR appears to pass through the basal ganglia via dopaminergic fibers, while the neurochemical basis of the TIR appears to include a circuit comprising the amygdala, the periaqueductal gray (PAG), the dorsal raphe, and the nucleus magnus raphe (NMR) via glutamatergic, serotonergic, cholinergic, GABAergic, and opioid fibers. For the DIR, the basal ganglia also seem to be involved in regard to estradiol, while for the TIR, the HPA axis appears involved at the level of the amygdala and the oral pontine reticular nucleus.
Asunto(s)
Encéfalo/metabolismo , Pérdida de Tono Postural/fisiología , Amígdala del Cerebelo/metabolismo , Analgésicos Opioides/metabolismo , Animales , Ganglios Basales/metabolismo , Dopamina/metabolismo , Núcleo Dorsal del Rafe/metabolismo , Femenino , Sistema Hipotálamo-Hipofisario/metabolismo , Masculino , Ratones , Actividad Motora/fisiología , Núcleo Magno del Rafe/metabolismo , Sustancia Gris Periacueductal/metabolismo , Ratas , Esteroides/metabolismo , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Patients deprived of cigarettes exhibit increased pain sensitivity during perioperative periods, yet the underlying neuroanatomical and molecular bases of this hypersensitivity are unclear. The present study showed that both the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were significantly decreased in a rat model of nicotine withdrawal. These rats showed less tryptophan hydroxylase 2 (TPH2) positive neurons and reduced TPH2 expression in the nucleus raphe magnus (NRM), and thus resulted in decreased 5-hydroxytryptamine (5-HT) levels in cerebrospinal fluid. Intrathecal injection of 5-HT or NRM microinjection of TPH-overexpression adeno-associated virus alleviated nicotine withdrawal-induced hyperalgesia, whereas 5-HT receptor pharmacological blockade by methysergide (a 5-HT receptor antagonist) exacerbated hypersensitivity and diminished the difference between the two groups. Together, these data indicate that hyperalgesia after nicotine withdrawal is mediated by declined descending serotonergic pathways in the NRM. This provides a new perspective to improve the postoperative pain management of patients, especially the smokers.
Asunto(s)
Regulación hacia Abajo/fisiología , Hiperalgesia/metabolismo , Nicotina/efectos adversos , Núcleo Magno del Rafe/metabolismo , Neuronas Serotoninérgicas/metabolismo , Síndrome de Abstinencia a Sustancias/metabolismo , Animales , Regulación hacia Abajo/efectos de los fármacos , Hiperalgesia/tratamiento farmacológico , Inyecciones Espinales , Inyecciones Subcutáneas , Masculino , Nicotina/administración & dosificación , Núcleo Magno del Rafe/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Receptores de Serotonina/metabolismo , Neuronas Serotoninérgicas/efectos de los fármacos , Serotonina/administración & dosificación , Serotonina/metabolismo , Síndrome de Abstinencia a Sustancias/tratamiento farmacológicoRESUMEN
Within the hindbrain, serotonin (5-HT) functions as a modulator of the central glucagon-like peptide-1 (GLP-1) system. This interaction between 5-HT and GLP-1 is achieved via 5-HT2C and 5-HT3 receptors and is relevant for GLP-1-mediated feeding behavior. The central GLP-1 system is activated by various stressors, activates the hypothalamic pituitary adrenocortical (HPA) axis, and contributes to stress-related behaviors. Whether 5-HT modulates GLP-1's role in the stress response in unknown. We hypothesized that the serotonergic modulation of GLP-1-producing neurons (i.e., PPG neurons) is stimuli-specific and that stressed-induced PPG activity is one of the modalities in which 5-HT plays a role. In this study, we investigated the roles of 5-HT2C and 5-HT3 receptors in mediating the activation of PPG neurons in the nucleus tractus solitarius (NTS) following exposure to three different acute stressors: lithium chloride (LiCl), noncontingent cocaine (Coc), and novel restraint stress (RES). Results showed that increased c-Fos expression in PPG neurons following LiCl and RES-but not Coc-is dependent on hindbrain 5-HT2C and 5-HT3 receptor signaling. Additionally, stressors that depend on 5-HT signaling to activate PPG neurons (i.e., LiCl and RES) increased c-Fos expression in 5-HT-expressing neurons within the caudal raphe (CR), specifically in the raphe magnus (RMg). Finally, we showed that RMg neurons innervate NTS PPG neurons and that some of these PPG neurons lie in close proximity to 5-HT axons, suggesting RMg 5-HT-expressing neurons are the source of 5-HT input responsible for engaging NTS PPG neurons. Together, these findings identify a direct RMg to NTS pathway responsible for the modulatory effect of 5-HT on the central GLP-1 system-specifically via activation of 5-HT2C and 5-HT3 receptors-in the facilitation of acute stress responses.
Asunto(s)
Péptido 1 Similar al Glucagón/metabolismo , Neuronas/metabolismo , Proteínas Proto-Oncogénicas c-fos/metabolismo , Receptor de Serotonina 5-HT2C/metabolismo , Receptores de Serotonina 5-HT3/metabolismo , Estrés Psicológico/metabolismo , Animales , Cocaína , Cloruro de Litio , Masculino , Vías Nerviosas/metabolismo , Núcleo Magno del Rafe/metabolismo , Proglucagón/metabolismo , Núcleos del Rafe/metabolismo , Ratas , Rombencéfalo/metabolismo , Neuronas Serotoninérgicas/metabolismo , Serotonina/metabolismo , Antagonistas del Receptor de Serotonina 5-HT2 , Antagonistas del Receptor de Serotonina 5-HT3 , Núcleo Solitario/metabolismo , Estrés FisiológicoRESUMEN
Psychophysical stress can cause neural changes that increase nociception in the orofacial region, particularly the masseter muscle (MM). The nucleus raphe magnus (NRM), which is located in the brain stem, serves the crucial role of regulating nociception through descending modulatory pain control. However, it remains unclear if neural activities in the NRM are affected under psychophysical stress conditions. This study conducted experiments to assess (1) whether neural activity, indicated by Fos expression in an NRM that has experienced MM injury, is affected by the stress of repeated forced swim tests (FST); and (2) whether the selective serotonin reuptake inhibitor fluoxetine administered daily after an FST could affect the number of Fos-positive neurons in the NRM. Results revealed that the stress from repeated FSTs significantly increased the number of Fos-positive neurons in an NRM that had been affected by MM injury. Fluoxetine inhibited increases in the number of Fos-positive neurons in the NRM that occurred as a result of FSTs, but this was not observed in sham rats. These findings indicate that the stress from FSTs could increase nociceptive neural activity in an NRM that has experienced MM injury. This could be due, in part, to changes in serotonergic mechanisms.
Asunto(s)
Nocicepción , Núcleo Magno del Rafe , Animales , Músculo Masetero , Neuronas , Núcleos del Rafe , RatasRESUMEN
This study examined the effect of prolonged water deprivation, in rat, on 5-HT and TH- immuno-expression in Dorsal Raphe Nucleus (DRN), Substantia Nigra pars compacta (SNc), Ventral Tegmental Area (VTA), and Magnus Raphe Nucleus (MRN). In parallel, we evaluated the anxiety state and pain perception in dehydrated rats. Our Findings revealed that dehydrated rats exhibited more preference for the dark compartment, suggesting that prolonged water deprivation is associated to an anxiogenic effect. After one week, 5 H T IR in the DRN of dehydrated rates showed a significant decrease. This was reversed to a significant increase post week 2 of dehydration. Our findings also demonstrated that TH-IR in DRN, MRN, SNc and VTA neuronal systems is significantly and gradually enhanced after 1-and-2-week osmotic stress. In addition, our results proved that all dehydrated rats were characterized by a significant and proportional rise of the reaction time to the nociceptive response in the hot plate test, as water deprivation duration increased, suggesting that dehydration caused a significant decrease in pain perception. Finally, the data described here clearly showed the implication of serotonin and dopamine neurotransmitter systems in the resistance to osmotic stress. Therefore, in this study, such central impairments were traduced by a few peripheral outcomes manifested by changes in mood state and nociception.
Asunto(s)
Ansiedad/metabolismo , Percepción del Dolor/fisiología , Serotonina/metabolismo , Tirosina 3-Monooxigenasa/metabolismo , Privación de Agua/fisiología , Animales , Ansiedad/fisiopatología , Conducta Animal/fisiología , Núcleo Dorsal del Rafe/metabolismo , Núcleo Dorsal del Rafe/fisiopatología , Masculino , Núcleo Magno del Rafe/metabolismo , Núcleo Magno del Rafe/fisiopatología , Presión Osmótica/fisiología , Porción Compacta de la Sustancia Negra/metabolismo , Porción Compacta de la Sustancia Negra/fisiopatología , Ratas , Ratas Wistar , Área Tegmental Ventral/metabolismo , Área Tegmental Ventral/fisiopatologíaRESUMEN
BACKGROUND: Acupuncture has been recommended as an alternative therapy for migraine. Emerging evidence suggests that the 5-HT7 receptor (5-HT7R) plays a significant facilitatory role in descending modulation in migraine pathophysiology, and that activation of 5-HT7R in the descending pathway is involved in migraine central sensitisation. OBJECTIVE: To investigate the ability of electroacupuncture (EA) to ameliorate central sensitisation via modulation of 5-HT7R in the descending pain pathways using a rat model of migraine induced by repetitive dural electrical stimulation (DES). DESIGN: 64 male Sprague-Dawley rats were randomly divided into four groups: Normal group; DES group (receiving dural electrical stimulation only); DES+GB20 group (DES model group treated with EA at GB20); and DES+Sham group (DES model group treated with EA at a non-traditional (sham) acupuncture point). The presence of cutaneous allodynia was determined by measuring facial and hind-paw withdrawal latencies to electronic von-Frey. The expression of 5-HT7R in the descending pathways (periaqueductal grey, raphe magnus nucleus, and trigeminal nucleus caudalis) was assessed using immunofluorescence and Western blotting. RESULTS: Facial and hind-paw withdrawal thresholds were significantly increased in the DES+GB20 group compared with the untreated DES group. The expression of 5-HT7R was significantly decreased in the DES+GB20 group compared with the DES group (one-way analysis of variance (ANOVA), P<0.05). No significant differences in behaviour or expression were found between the rats in the DES+Sham group and the untreated DES group (one-way ANOVA, P>0.05). CONCLUSION: EA at GB20 may ameliorate central sensitisation in migraine by inhibiting the activation of 5-HT7 receptors in the descending pain pathway in a rat model of migraine.
Asunto(s)
Electroacupuntura , Trastornos Migrañosos/terapia , Receptores de Serotonina/metabolismo , Puntos de Acupuntura , Animales , Humanos , Masculino , Trastornos Migrañosos/genética , Trastornos Migrañosos/metabolismo , Núcleo Magno del Rafe/metabolismo , Sustancia Gris Periacueductal/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores de Serotonina/genéticaRESUMEN
Multiple sclerosis is among the most common causes of neurological disabilities in young adults. Over the past decade, several therapeutic strategies have emerged as having potential neuroprotective and neuroregenerative properties. We investigated the effect of intranasal administration of LINGO-1-directed siRNA-loaded chitosan nanoparticles on demyelination and remyelination processes in a rat model of demyelination. Adult male Wistar rats were randomly assigned to one of 6 groups (n = 10 each) and subjected to intrapontine stereotaxic injection of ethidium bromide (EB) to induce demyelination. EB-treated rats were either left untreated or received intranasal LINGO-1-directed siRNA-chitosan nanoparticles from day 1 to day 7 (demyelination group) or from day 7 to day 21 (remyelination group) after EB injection. Chitosan nanoparticle (50 µl) was given alone after EB stereotaxic injection for both demyelination and remyelination groups. Two additional groups received 10 µl of saline by stereotaxic injection, followed by intranasal saline as controls for demyelination and remyelination groups (n = 10/group). Behavioural testing was conducted for all rats, as well as terminal biochemical assays and pathological examination of pontine tissues were done. After EB injection, rats had compromised motor performance and coordination. Pathological evidence of demyelination was observed in pontine tissue and higher levels of caspase-3 activity were detected compared to control rats. With LINGO-1-directed siRNA-chitosan nanoparticle treatment, animals performed better than controls. Remyelination-treated group showed better motor performance than demyelination group. LINGO-1 downregulation was associated with signs of repair in histopathological sections, higher expression of pontine myelin basic protein (MBP) mRNA and protein and lower levels of caspase-3 activity indicating neuroprotection and remyelination enhancement.
Asunto(s)
Ataxia/terapia , Enfermedades Desmielinizantes/terapia , Proteínas de la Membrana/antagonistas & inhibidores , Nanopartículas/química , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Fármacos Neuroprotectores/administración & dosificación , ARN Interferente Pequeño/genética , Remielinización/genética , Administración Intranasal , Animales , Ataxia/inducido químicamente , Ataxia/genética , Ataxia/patología , Caspasa 3/genética , Caspasa 3/metabolismo , Quitosano/química , Enfermedades Desmielinizantes/inducido químicamente , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/patología , Modelos Animales de Enfermedad , Portadores de Fármacos , Composición de Medicamentos/métodos , Etidio/toxicidad , Regulación de la Expresión Génica , Masculino , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Proteína Básica de Mielina/agonistas , Proteína Básica de Mielina/genética , Proteína Básica de Mielina/metabolismo , Vaina de Mielina/metabolismo , Vaina de Mielina/patología , Nanopartículas/administración & dosificación , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Núcleo Magno del Rafe/efectos de los fármacos , Núcleo Magno del Rafe/metabolismo , Núcleo Magno del Rafe/patología , ARN Interferente Pequeño/metabolismo , Ratas , Ratas Wistar , Técnicas EstereotáxicasRESUMEN
The electrical stimulation of the dorsolateral columns of the periaquedutal grey matter (dlPAG) or deep layers of the superior colliculus (dlSC) evokes defensive behaviours followed by an antinociceptive response. Monoaminergic brainstem reticular nuclei are suggested to comprise the endogenous pain modulatory system. The aim of the present work was to investigate the role played by 5-HT2 subfamily of serotonergic receptors of the nucleus raphe magnus (NRM) and the gigantocellularis/paragigantocellularis pars α reticular nuclei (Gi/PGiα) in the elaboration of instinctive fear-induced antinociception elicited by electrical stimulation of dlPAG or of dlSC. The nociceptive thresholds were measured by the tail-flick test in Wistar rats. The 5-HT2A/2C-serotonergic receptors antagonist ritanserin was microinjected at different concentrations (0.05, 0.5 and 5.0µg/0.2µL) either in Gi/PGiα or in NRM. The blockade of 5-HT2 receptors in both Gi/PGiα and NRM decreased the innate fear-induced antinociception elicited by electrical stimulation of the dlSC or the dlPAG. These findings indicate that serotonin is involved in the hypo-algesia induced by unconditioned fear-induced behavioural responses and the 5-HT2A/2C-serotonergic receptor subfamily in neurons situated in the Gi/PGiα complex and NRM are critically recruited in pain modulation during the panic-like emotional behaviour.
Asunto(s)
Miedo/fisiología , Núcleo Magno del Rafe/metabolismo , Sustancia Gris Periacueductal/fisiología , Núcleos del Rafe/metabolismo , Receptor de Serotonina 5-HT2A/metabolismo , Receptor de Serotonina 5-HT2C/metabolismo , Colículos Superiores/fisiología , Animales , Condicionamiento Clásico , Estimulación Eléctrica , Masculino , Vías Nerviosas/fisiología , Dolor/patología , Dolor/fisiopatología , Dimensión del Dolor , Umbral del Dolor/fisiología , Ratas , Ratas Wistar , Ritanserina/farmacología , Antagonistas de la Serotonina/farmacologíaRESUMEN
BACKGROUND: While electroacupuncture (EA) pretreatment has been found to ameliorate migraine-like symptoms, the underlying mechanisms remain poorly understood. Emerging evidence suggests that the brainstem descending pain modulatory system, comprising the periaqueductal grey (PAG), raphe magnus nucleus (RMg), and trigeminal nucleus caudalis (TNC), may be involved in migraine pathophysiology. We hypothesised that EA would ameliorate migraine-like symptoms via modulation of this descending system. METHODS: We used a conscious rat model of migraine induced by repeated electrical stimulation of the dura. Forty male Sprague-Dawley rats were randomly assigned to one of four groups: an EA group, which received EA at GB20 following dural stimulation; a sham acupuncture (SA) group, which received manual acupuncture at a non-acupuncture point following dural stimulation; a Model group, which received dural stimulation but no acupuncture; and a Control group, which received neither dural stimulation nor acupuncture (electrode implantation only). HomeCageScan was used to measure effects on behaviour, and immunofluorescence staining was used to examine neural activation (c-Fos immunoreactivity) in the PAG, RMg, and TNC. RESULTS: Compared to the Model group, rats in the EA group showed a significant increase in exploratory, locomotor and eating/drinking behaviour (p<0.01) and a significant decrease in freezing-like resting and grooming behaviour (p<0.05). There was a significant increase in the mean number of c-Fos neurons in the PAG, RMg, and TNC in Model versus Control groups (p<0.001); however, this was significantly attenuated by EA treatment (p<0.001). There were no significant differences between the SA and Model groups in behaviour or c-Fos immunoreactivity. CONCLUSIONS: EA pretreatment ameliorates behavioural changes in a rat model of recurrent migraine, possibly via modulation of the brainstem descending pathways.
Asunto(s)
Puntos de Acupuntura , Electroacupuntura , Trastornos Migrañosos/terapia , Animales , Modelos Animales de Enfermedad , Ingestión de Alimentos , Humanos , Locomoción , Masculino , Trastornos Migrañosos/fisiopatología , Núcleo Magno del Rafe/fisiopatología , Sustancia Gris Periacueductal/fisiopatología , Ratas , Ratas Sprague-DawleyRESUMEN
The efficacy of opioids in patients with chronic neuropathic pain remains controversial. Although activation of δ-opioid receptors (DORs) in the brainstem reduces inflammation-induced persistent hyperalgesia, it is not effective under persistent neuropathic pain conditions and these clinical problems remain largely unknown. In this study, by using a chronic constriction injury (CCI) of the sciatic nerve in rats, we found that in the brainstem nucleus raphe magnus (NRM), DORs emerged on the surface membrane of central synaptic terminals on day 3 after CCI surgery and disappeared on day 14. Histone deacetylase (HDAC) inhibitors microinjected into the NRM in vivo increased the level of synaptosomal DOR protein and NRM infusion of DOR agonists producing an antinociceptive effect in a nerve growth factor (NGF) signaling-dependent manner. In vitro, in CCI rat slices incubated with HDAC inhibitors, DOR agonists significantly inhibited EPSCs. This effect was blocked by tyrosine receptor kinase A antagonists. Chromatin immunoprecipitation analysis revealed that NRM infusion of HDAC inhibitors in CCI rats increased the level of histone H4 acetylation at Ngf gene promoter regions. NGF was infused into the NRM or incubated CCI rat slices drove DORs to the surface membrane of synaptic terminals. Taken together, epigenetic upregulation of NGF activity by HDAC inhibitors in the NRM promotes the trafficking of DORs to pain-modulating neuronal synapses under neuropathic pain conditions, leading to δ-opioid analgesia. These findings indicate that therapeutic use of DOR agonists combined with HDAC inhibitors might be effective in chronic neuropathic pain managements.
Asunto(s)
Analgésicos/farmacología , Dolor Crónico/tratamiento farmacológico , Inhibidores de Histona Desacetilasas/farmacología , Neuralgia/tratamiento farmacológico , Receptores Opioides delta/metabolismo , Sinapsis/metabolismo , Animales , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Dolor Crónico/metabolismo , Modelos Animales de Enfermedad , Epigénesis Genética , Histonas/metabolismo , Ácidos Hidroxámicos/metabolismo , Masculino , Neuralgia/metabolismo , Núcleo Magno del Rafe/efectos de los fármacos , Núcleo Magno del Rafe/metabolismo , Ratas Wistar , Receptores Opioides delta/agonistas , Nervio Ciático/fisiopatología , Sinapsis/efectos de los fármacos , Factores de Tiempo , Técnicas de Cultivo de TejidosRESUMEN
OBJECTIVES: To investigate the effect of pure passive movement on both cortical and subcortical somatosensory evoked potentials (SEPs). METHODS: Median nerve SEPs were recorded in 8 patients suffering from Parkinson's disease (PD) and two patients with essential tremor. PD patients underwent electrode implantation in the subthalamic (STN) nucleus (3 patients) and pedunculopontine (PPTg) nucleus (5 patients), while 2 patients with essential tremor were implanted in the ventral intermediate nucleus (VIM) of the thalamus. In anesthetized patients, SEPs were recorded at rest and during a passive movement of the thumb of the stimulated wrist from the intracranial electrode contacts and from the scalp. Also the high-frequency oscillations (HFOs) were analyzed. RESULTS: Amplitudes of both deep and scalp components were decreased during passive movement, but the reduction was higher at cortical than subcortical level. Also the HFOs were reduced by movement. CONCLUSION: The different amount of the movement-related decrease suggests that the cortical SEP gating is not only the result of a subcortical somatosensory volley attenuation, but a further mechanism acting at cortical level should be considered. SIGNIFICANCE: Our results are important for understanding the physiological mechanism of the sensory-motor interaction during passive movement.