Electroacupuncture effects on the P2X4R pathway in microglia regulating the excitability of neurons in the substantia gelatinosa region of rats with spinal nerve ligation.

Electroacupuncture (EA) has been used to treat neuropathic pain induced by peripheral nerve injury (PNI) by applying an electrical current to acupoints with acupuncture needles. However, the mechanisms by which EA treats pain remain indistinct. High P2X4 receptor (P2X4R) expression levels demonstrate a notable increase in hyperactive microglia in the ipsilateral spinal dorsal horn following PNI. In order to demonstrate the possibility that EA analgesia is mediated in part by P2X4R in hyperactive microglia, the present study performed mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests in male Sprague­Dawley rats that had undergone spinal nerve ligation (SNL). The expression levels of spinal P2X4R were determined using reverse transcription­quantitative PCR, western blotting analysis and immunofluorescence staining. Furthermore, spontaneous excitatory postsynaptic currents (sEPSCs) were recorded using whole­cell patch clamp to demonstrate the effect of EA on synaptic transmission in rat spinal substantia gelatinosa (SG) neurons. The results of the present study demonstrated that EA increased the MWT and TWL and decreased overexpression of P2X4R in hyperactive microglia in SNL rats. Moreover, EA attenuated the frequency of sEPSCs in SG neurons in SNL rats. The results of the present study indicate that EA may mediate P2X4R in hyperactive spinal microglia to inhibit nociceptive transmission of SG neurons, thus relieving pain in SNL rats.

Atractylenolide III ameliorates cerebral ischemic injury and neuroinflammation associated with inhibiting JAK2/STAT3/Drp1-dependent mitochondrial fission in microglia.

BACKGROUND: Inflammation is a major contributor to stroke pathology, making it a promising strategy for intervention. Microglia, the resident macrophages in the brain, play essential roles in both the generation and resolution of neuroinflammation. In particular, mitochondrial homeostasis is critical for microglial function and its dysregulation is involved in the pathogenesis of ischemic stroke. Atractylenolide III (A III), a sesquiterpene lactone found in Atractylodes macrocephala Koidz, has been shown to have an inhibitory effect on inflammation. However, its effect specifically on neuroinflammation and microglial mitochondrial homeostasis following stroke remains elusive. HYPOTHESIS: We hypothesized that A III protects against brain ischemia through inhibition of neuroinflammation mediated by JAK2/STAT3/Drp1-dependent mitochondrial fission. METHODS: The neuroprotective and anti-neuroinflammatory effects of A III were investigated in vivo in mice with transient occlusion to the middle cerebral artery (MCAO) and in vitro in oxygen glucose deprivation-reoxygenation (OGDR)-stimulated primary microglia from mice. RESULTS: A III and AG490, an inhibitor of JAK2, treatment reduced brain infarct size, restored cerebral blood flow (CBF), ameliorated brain edema and improved neurological deficits in MCAO mice. Furthermore, A III and AG490 inhibited mRNA and protein expressions of proinflammatory (IL-1ß, TNF-α, and IL-6) and anti-inflammatory cytokines in both MCAO mice and OGDR-stimulated primary microglia. The JAK2/STAT3 pathway was effectively suppressed by A III, similar to the effect of AG490 treatment. In addition, A III and AG490 treatments significantly decreased Drp1 phosphorylation, translocation and mitochondrial fission in primary microglia stimulated with OGDR for 24 h. CONCLUSION: Our study demonstrated that A III was able to reduce complications associated with ischemia through inhibiting neuroinflammation, which was mediated in part by JAK2/STAT3-dependent mitochondrial fission in microglia.

KCC2-GABAA pathway correlates with the analgesic effect of electro-acupuncture in CCI rats.

Potassium-chloride cotransporter 2 (KCC2) has been indicated to serve a crucial role during chronic neuropathic pain (NP). Following the emergence of NP, γ­aminobutyric acid (GABA) A receptor­mediated signaling may be further impaired by the changes of KCC2 chloride anion gradient. In the present study, the authors investigate the effect of electro-acupuncture (EA) on the behavior and the expression of KCC2 and GABAA receptor γ2 subunit in the spinal cord of chronic constriction injury (CCI) model rats. A total of 60 adult male Sprague­Dawley rats were divided into four groups: Normal group, sham­CCI group, CCI group and CCI+EA group. The effect of EA was assessed via the values of mechanical withdrawal threshold and thermal withdrawal latency, which were significantly improved upon stimulation of the ST­36 and GB­34 acupoints. In addition, a marked reduction in both the mRNA and protein levels of KCC2 and GABAA receptor γ2 subunit was observed in the spinal cord following loose ligation of the sciatic nerve. The reductions in KCC2 and GABAA receptor γ2 subunit expression were reversed by EA treatment. These results support the notion that KCC2 and GABAA receptor γ2 subunit contribute to NP following peripheral nerve injury and extend the understanding of the analgesic effects of EA on NP.