RESUMEN
BACKGROUND: Fibromyalgia (FM) is a syndrome involving chronic pain, fatigue, sleep difficulties, morning stiffness and muscle cramping lasting longer than 3 months. The epidemiological prevalence is approximately 3-5% in women and increases with age. Antagonism of acid-sensing ion channel 3 (ASIC3) reportedly attenuates acid saline-induced FM pain in mice. AIMS: Whether pre-treatment with electroacupuncture (EA) or APETx2 can attenuate mechanical hyperalgesia in this murine model remains unknown. METHODS: Accordingly, we examined the analgesic effect of EA in a murine model of FM pain induced by dual injections of acid saline and investigated whether EA or APETx2 can attenuate FM pain via the ASIC3 channel. RESULTS: EA significantly reduced mechanical hyperalgesia in this model. ASIC3 antagonism, induced by injecting APETx2, also significantly reduced mechanical hyperalgesia. The expression of ASIC3 in the dorsal root ganglia, spinal cord and thalamus was increased after FM model induction. Over-expression of these nociceptive channels was attenuated by pre-treatment with EA or an ASIC3 antagonist. CONCLUSION: Our data reveal that both EA and ASIC3 blockade significantly reduce FM pain in mice via the ASIC3, Nav1.7 and Nav1.8 signalling pathways. Moreover, our findings support the potential clinical use of EA for the treatment of FM pain.
Asunto(s)
Bloqueadores del Canal Iónico Sensible al Ácido/farmacología , Canales Iónicos Sensibles al Ácido/metabolismo , Electroacupuntura/métodos , Fibromialgia/terapia , Hiperalgesia/terapia , Manejo del Dolor/métodos , Bloqueadores del Canal Iónico Sensible al Ácido/administración & dosificación , Animales , Terapia Combinada , Modelos Animales de Enfermedad , Femenino , RatonesRESUMEN
BACKGROUND: The mechanisms underlying fibromyalgia (FM) pain are not understood. The US Food and Drug Administration has recommended three drugs for treating FM-namely, pregabalin, duloxetine and milnacipran; however, these medications are associated with severe side effects. OBJECTIVE: To create a mouse model of FM pain using dual injections of acidic saline to cause mechanical hyperalgesia and test whether ASIC3, Nav1.7 and Nav1.8 are involved in this process and whether electroacupuncture (EA) can reverse these phenomena. METHODS: The FM model was established by injecting acidic saline twice into 40 ICR mice. The mice were assigned to subgroups (n=8 each) treated with different EA frequencies (2, 15 and 50 Hz). ASIC3, Nav1.7 and Nav1.8 expression levels were measured by Western blotting and immunohistochemistry. RESULTS: Significant mechanical hyperalgesia was induced on day 8 in FM mice, which was reversed by 2, 15 and 50 Hz EA. ASIC3, Nav1.7 and Nav1.8 protein levels increased significantly in both the dorsal root ganglion and in the spinal cord of FM model mice. These changes were further attenuated by 2, 15 and 50 Hz EA. CONCLUSION: Reduced nociceptive ASIC3, Nav1.7 and Nav1.8 proteins are involved in the preventive effects of EA against FM, and this series of molecules may represent targets for FM treatment.
Asunto(s)
Canales Iónicos Sensibles al Ácido/metabolismo , Electroacupuntura , Fibromialgia/metabolismo , Fibromialgia/terapia , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Canal de Sodio Activado por Voltaje NAV1.8/metabolismo , Canales Iónicos Sensibles al Ácido/genética , Animales , Modelos Animales de Enfermedad , Fibromialgia/genética , Ganglios Espinales/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos ICR , Canal de Sodio Activado por Voltaje NAV1.7/genética , Canal de Sodio Activado por Voltaje NAV1.8/genética , Manejo del Dolor , Médula Espinal/metabolismoRESUMEN
Many scientists are seeking better therapies for treating fibromyalgia (FM) pain. We used a mouse model of FM to determine if ASIC3 and its relevant signaling pathway participated in FM pain. We demonstrated that FM-induced mechanical hyperalgesia was attenuated by electroacupuncture (EA). The decrease in fatigue-induced lower motor function in FM mice was also reversed by EA. These EA-based effects were abolished by the opioid receptor antagonist naloxone and the adenosine A1 receptor antagonist rolofylline. Administration of opioid receptor agonist endomorphin (EM) or adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) has similar results to EA. Similar results were also observed in ASIC3-/- or ASIC3 antagonist (APETx2) injected mice. Using western blotting, we determined that pPKA, pPI3K, and pERK were increased during a dual acidic injection priming period. Nociceptive receptors, such as ASIC3, Nav1.7, and Nav1.8, were upregulated in the dorsal root ganglion (DRG) and spinal cord (SC) of FM mice. Furthermore, pPKA, pPI3K, and pERK were increased in the central thalamus. These aforementioned mechanisms were completely abolished in ASIC3 knockout mice. Electrophysiological results also indicated that acid potentiated Nav currents through ASIC3 and ERK pathway. Our results highlight the crucial role of ASIC3-mediated mechanisms in the treatment of FM-induced mechanical hyperalgesia.