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OBJECTIVE: The study aimed to investigate the involvement of astrocytes in the medullary dorsal horn (MDH) in the orofacial hyperalgesia induced by experimental tooth movement (ETM) and related mechanism. MATERIALS AND METHODS: Experimental tooth movement was produced with nickel-titanium alloy closed-coil spring fixed between the left maxillary first molar and the left upper incisor. Fluorocitrate was administrated through medullary subarachnoid at 3 days after ETM. Pressure pain threshold (PPT) in masseter cutaneous area was measured. The expression of glial fibrillary acidic protein (GFAP) and c-Fos in MDH was measured using immunofluoroscence staining. The expression of interleukin-1ß (IL-1ß) and phosphorylated N-methyl-D-aspartic acid (NMDA) receptor subunit NR1 (p-NR1) was measured with Western blotting. RESULTS: Experimental tooth movement-induced orofacial hyperalgesia from 1 to 9 days as the PPT was significantly reduced (P < .05). Immunofluoroscence staining showed that the expression of c-Fos in MDH was dramatically upregulated at 1 day and 3 days after ETM, while GFAP expression with both immunofluoroscence staining and Western blotting was significantly enhanced at 3 days and 7 days after ETM. Western blotting analysis indicated that the expression of IL-1ß and p-NR1 in MDH was significantly enhanced at 3 days after ETM. Furthermore, we found that fluorocitrate administration at 3 days after ETM could markedly suppress the expression of c-Fos, GFAP, IL-1ß and p-NR1 and attenuate the reduction of PPT induced by ETM. CONCLUSION: Astrocyte activation in MDH is involved in the mechanical hyperalgesia, and the subsequent upregulated IL-1ß and overexpression of p-NR1 may participate in this process.
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Astrocitos , Hiperalgesia , Animales , Proteína Ácida Fibrilar de la Glía , Umbral del Dolor , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Robust activation of glial cells has been reported to occur particularly during the pathogenesis of bone cancer pain (BCP). Researchers from our group and others have shown that histone deacetylases (HDACs) play a significant role in modulating glia-mediated immune responses; however, it still remains unclear whether HDACs are involved in the activation of glial cells during the development of BCP. METHODS: BCP model was established by intra-tibia tumor cell inoculation (TCI). The expression levels and distribution sites of histone deacetylases (HDACs) in the spinal dorsal horn and dorsal root ganglia were evaluated by Western blot and immunofluorescent staining, respectively. Suberoylanilide hydroxamic acid (SAHA), a clinically used HDAC inhibitor, was then intraperitoneally and intrathecally injected to rescue the increased expression levels of HDAC1 and HDAC2. The analgesic effects of SAHA administration on BCP were then evaluated by measuring the paw withdrawal thresholds (PWTs). The effects of SAHA on activation of glial cells and expression of proinflammatory cytokines (TNF-α, IL-1ß, and IL-6) in the spinal dorsal horn and dorsal root ganglia of TCI rats were further evaluated by immunofluorescent staining and Western blot analysis. Subsequently, the effects of SAHA administration on tumor growth and cancer cell-induced bone destruction were analyzed by hematoxylin and eosin (HE) staining and micro-CT scanning. RESULTS: TCI caused rapid and long-lasting increased expression of HDAC1/HDAC2 in glial cells of the spinal dorsal horn and dorsal root ganglia. Inhibiting HDACs by SAHA not only reversed TCI-induced upregulation of HDACs but also inhibited the activation of glial cells in the spinal dorsal horn and dorsal root ganglia, and relieved TCI-induced mechanical allodynia. Further, we found that SAHA administration could not prevent cancer infiltration or bone destruction in the tibia, which indicated that the analgesic effects of SAHA were not due to its anti-tumor effects. Moreover, we found that SAHA administration could inhibit GSK3ß activity in the spinal dorsal horn and dorsal root ganglia, which might contributed to the relief of BCP. CONCLUSION: Our findings suggest that HDAC1 and HDAC2 are involved in the glia-mediated neuroinflammation in the spinal dorsal horn and dorsal root ganglia underlying the pathogenesis of BCP, which indicated that inhibiting HDACs by SAHA might be a potential strategy for pain relief of BCP.
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Dolor en Cáncer/metabolismo , Ganglios Espinales/efectos de los fármacos , Inhibidores de Histona Desacetilasas/farmacología , Neuroglía/efectos de los fármacos , Asta Dorsal de la Médula Espinal/efectos de los fármacos , Vorinostat/farmacología , Analgésicos/farmacología , Animales , Neoplasias Óseas/complicaciones , Femenino , Ganglios Espinales/metabolismo , Neuroglía/metabolismo , Ratas , Ratas Sprague-Dawley , Asta Dorsal de la Médula Espinal/metabolismoRESUMEN
Malocclusion is an important risk factor for temporomandibular disorder (TMD), a series of disorders characterized by dysfunction in the orofacial region involving the temporomandibular joint (TMJ) and jaw muscles. We recently showed that experimental unilateral anterior crossbite (UAC) produced masseter hyperactivity through a circuit involving the periodontal proprioception, trigeminal mesencephalic nucleus (Vme), and trigeminal motor nucleus (Vmo). Anxiety is a common complication in patients with TMD. The lateral habenula (LHb) is involved in emotional modulation and has direct projections to the Vme. Therefore, the present research examined whether UAC facilitates excitatory input from the LHb to the Vme and, subsequently, anxiety-like behaviors in rats. The LHb activation was evaluated by the electrophysiological recording, assessment of vesicular glutamate transporter-2 (VGLUT2) mRNA expression, and measurement of anxiety-like behaviors. The effects of LHb activity on Vme were evaluated by electrophysiological recording from Vme neurons and local changes in VGLUT2 protein density. UAC produced anxiety in modeled rats and increased neuronal activity in the LHb. VGLUT2 mRNA expression was also increased in the LHb. Further, VGLUT2-positive boutons were observed in close apposite upon parvalbumin (PV)-labeled Vme neurons. VGLUT2 protein expression was also increased in the Vme. Significantly, injection of VGLUT2-targeted shRNA into the LHb reduced the expression of VGLUT2 protein in the Vme, attenuated UAC-associated anxiety-like behaviors, and attenuated electrophysiological changes in the Vme neurons. In conclusion, we show that UAC activates the LHb neurons as well as the periodontal proprioceptive pathway to provide excitatory input to the Vme and produce anxiety in rats. These findings provide a rationale for suppressing activity of the LHb to attenuate both the physical and psychological effects of TMD.
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BACKGROUND: Previous studies presumed that the disturbed neurovascular coupling to be a critical risk factor of cognitive impairments in type 2 diabetes mellitus (T2DM), but distinct clinical manifestations were lacked. Consequently, we decided to investigate the neurovascular coupling in T2DM patients by exploring the MRI relationship between neuronal activity and the corresponding cerebral blood perfusion. METHODS: Degree centrality (DC) map and amplitude of low-frequency fluctuation (ALFF) map were used to represent neuronal activity. Cerebral blood flow (CBF) map was used to represent cerebral blood perfusion. Correlation coefficients were calculated to reflect the relationship between neuronal activity and cerebral blood perfusion. RESULTS: At the whole gray matter level, the manifestation of neurovascular coupling was investigated by using 4 neurovascular biomarkers. We compared these biomarkers and found no significant changes. However, at the brain region level, neurovascular biomarkers in T2DM patients were significantly decreased in 10 brain regions. ALFF-CBF in left hippocampus and fractional ALFF-CBF in left amygdala were positively associated with the executive function, while ALFF-CBF in right fusiform gyrus was negatively related to the executive function. The disease severity was negatively related to the memory and executive function. The longer duration of T2DM was related to the milder depression, which suggests T2DM-related depression may not be a physiological condition but be a psychological condition. CONCLUSION: Correlations between neuronal activity and cerebral perfusion maps may be a method for detecting neurovascular coupling abnormalities, which could be used for diagnosis in the future. Trial registry number: This study has been registered in ClinicalTrials.gov (NCT02420470) on April 2, 2015 and published on July 29, 2015.
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Amígdala del Cerebelo/fisiopatología , Disfunción Cognitiva/fisiopatología , Diabetes Mellitus Tipo 2/fisiopatología , Función Ejecutiva/fisiología , Neuroimagen Funcional/métodos , Sustancia Gris/fisiopatología , Hipocampo/fisiopatología , Acoplamiento Neurovascular/fisiología , Adulto , Amígdala del Cerebelo/diagnóstico por imagen , Biomarcadores , Disfunción Cognitiva/diagnóstico por imagen , Disfunción Cognitiva/etiología , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/diagnóstico por imagen , Femenino , Sustancia Gris/diagnóstico por imagen , Hipocampo/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética , Masculino , Recuerdo Mental/fisiología , Persona de Mediana EdadRESUMEN
Bone cancer pain (BCP) profoundly compromises the life quality of patients with bone metastases. Severe side effects of the drugs which were widely used and effective in the various stages of this condition results in a huge challenge for BCP treatment. Here, we investigated the antinociceptive effects of XPro1595, a soluble tumor necrosis factor (solTNF) inhibitor with considerable immunoregulatory efficacy, on BCP, as well as the underlying mechanisms within the spinal dorsal horn (SDH). Walker 256 mammary gland carcinoma cells were intratibially inoculated to induce BCP. Intrathecal administration of XPro1595 alleviated bone cancer-induced chronic pain in a dose-dependent manner, with an ED50 of 9.69 mg/kg. Bone cancer resulted in the activation of astrocytes and microglia in the SDH through the upregulation of mitogen-activated protein kinase (MAPK) pathways, which was accompanied by an over-expression of pro-inflammatory cytokines, including TNF-α, IL-1ß, and IL-6. XPro1595suppressed bone cancer-evoked glial activation and the consequent neuroinflammation. These inhibitory effects of XPro1595 were, at least partially, mediated by a reduction in the phosphorylation of p38 MAPK in spinal glial cells. In conclusion, inhibition of spinal glia by XPro1595 may have utility in the treatment of bone cancer-induced neuroinflammation, and our results further implicate XPro1595 as a new promising therapeutic agent for BCP.
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Neoplasias Óseas/tratamiento farmacológico , Dolor en Cáncer/tratamiento farmacológico , Neuroglía/efectos de los fármacos , Asta Dorsal de la Médula Espinal/efectos de los fármacos , Factor de Necrosis Tumoral alfa/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Astrocitos/patología , Neoplasias Óseas/metabolismo , Neoplasias Óseas/patología , Dolor en Cáncer/metabolismo , Dolor en Cáncer/patología , Citocinas/metabolismo , Femenino , Inyecciones Espinales/métodos , Microglía/efectos de los fármacos , Microglía/metabolismo , Microglía/patología , Neuroglía/metabolismo , Neuroglía/patología , Ratas , Ratas Sprague-Dawley , Asta Dorsal de la Médula Espinal/metabolismo , Asta Dorsal de la Médula Espinal/patología , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
The easily developed morphine tolerance in bone cancer pain (BCP) significantly hindered its clinical use. Increasing evidence suggests that histone deacetylases (HDACs) regulate analgesic tolerance subsequent to continuous opioid exposure. However, whether HDACs contribute to morphine tolerance in the pathogenesis of BCP is still unknown. In the current study, we explored the possible engagement of HDACs in morphine tolerance during the pathogenesis of BCP. After intra-tibia tumor cell inoculation (TCI), we found that the increased expression of HDACs was negatively correlated with the decreased expression of MOR in the DRG following TCI. The paw withdrawal threshold (PWT) and percentage maximum possible effects (MPEs) decreased rapidly in TCI rats when morphine was used alone. In contrast, the concomitant use of SAHA and morphine significantly elevated the PWT and MPEs of TCI rats compared to morphine alone. Additionally, we found that SAHA administration significantly elevated MOR expression in the DRG of TCI rats with or without morphine treatment. Moreover, the TCI-induced increase in the co-expression of MOR and HDAC1 in neurons was significantly decreased after SAHA administration. These results suggest that HDACs are correlated with the downregulation of MOR in the DRG during the pathogenesis of BCP. Inhibition of HDACs using SAHA can be used to attenuate morphine tolerance in BCP.
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BACKGROUND: Bone cancer pain (BCP) severely compromises the quality of life, while current treatments are still unsatisfactory. Here, we tested the antinociceptive effects of triptolide (T10), a substance with considerable anti-tumor efficacies on BCP, and investigated the underlying mechanisms targeting the spinal dorsal horn (SDH). METHODS: Intratibial inoculation of Walker 256 mammary gland carcinoma cells was used to establish a BCP model in rats. T10 was intrathecally injected, and mechanical allodynia was tested by measuring the paw withdrawal thresholds (PWTs). In mechanism study, the activation of microglia, astrocytes, and the mitogen-activated protein kinase (MAPK) pathways in the SDH were evaluated by immunofluorescence staining or Western blot analysis of Iba-1, GFAP, p-ERK, p-p38, and p-JNK. The expression and cellular localization of histone deacetylases (HDACs) 1 and 2 were also detected to investigate molecular mechanism. RESULTS: Intrathecal injection of T10 inhibited the bone cancer-induced mechanical allodynia with an ED50 of 5.874 µg/kg. This effect was still observed 6 days after drug withdrawal. Bone cancer caused significantly increased expression of HDAC1 in spinal microglia and neurons, with HDAC2 markedly increased in spinal astrocytes, which were accompanied by the upregulation of MAPK pathways and the activation of microglia and astrocytes in the SDH. T10 reversed the increase of HDACs, especially those in glial cells, and inhibited the glial activation. CONCLUSIONS: Our results suggest that the upregulation of HDACs contributes to the pathological activation of spinal glial cells and the chronic pain caused by bone cancer, while T10 help to relieve BCP possibly via inhibiting the upregulation of HDACs in the glial cells in the SDH and then blocking the neuroinflammation induced by glial activation.
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Analgésicos/uso terapéutico , Neoplasias Óseas/tratamiento farmacológico , Dolor en Cáncer/tratamiento farmacológico , Diterpenos/uso terapéutico , Inhibidores de Histona Desacetilasas/uso terapéutico , Neuroglía/efectos de los fármacos , Fenantrenos/uso terapéutico , Analgésicos/farmacología , Animales , Neoplasias Óseas/enzimología , Dolor en Cáncer/enzimología , Diterpenos/farmacología , Compuestos Epoxi/farmacología , Compuestos Epoxi/uso terapéutico , Femenino , Inhibidores de Histona Desacetilasas/farmacología , Histona Desacetilasas/metabolismo , Neuroglía/enzimología , Fenantrenos/farmacología , Ratas , Ratas Sprague-Dawley , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Resultado del Tratamiento , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/fisiologíaRESUMEN
Two neutral merocyanine-based near-infrared fluorescent probes were for the first time developed through rational engineering of the classical cationic cyanine scaffold IR-780 for in vivo imaging of amyloid-ß plaques. In vivo NIRF imaging revealed that the probe could penetrate the blood-brain barrier and efficiently differentiate the living transgenic and wild-type mice.
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Péptidos beta-Amiloides/análisis , Benzopiranos/química , Colorantes Fluorescentes/química , Indoles/química , Rayos Infrarrojos , Imagen Óptica , Placa Amiloide/diagnóstico por imagen , Espectrometría de Fluorescencia , Benzopiranos/síntesis química , Colorantes Fluorescentes/análisis , Colorantes Fluorescentes/síntesis química , Humanos , Indoles/síntesis química , Estructura MolecularRESUMEN
Combined the retrograde double tracing with immunofluorescence histochemical staining, we examined the neurons in the lateral parabrachial nucleus (LPB) sent collateral projections to the paraventricular thalamic nucleus (PVT) and central amygdaloid nucleus (CeA) and their roles in the nociceptive transmission in the rat. After the injection of Fluoro-gold (FG) into the PVT and tetramethylrhodamine-dextran (TMR) into the CeA, respectively, FG/TMR double-labeled neurons were observed in the LPB. The percentages of FG/TMR double-labeled neurons to the total number of FG- or TMR-labeled neurons were 6.18% and 9.09%, respectively. Almost all of the FG/TMR double-labeled neurons (95%) exhibited calcitonin gene-related peptide (CGRP) immunoreactivity. In the condition of neuropathic pain, 94% of these neurons showed FOS immunoreactivity. The present data indicates that some of CGRP-expressing neurons in the LPB may transmit nociceptive information toward the PVT and CeA by way of axon collaterals.