大麻素CB1受体的激活抑制大鼠背根神经节神经元中HCN通道的功能。
Activation of cannabinoid CB1 receptors suppresses HCN channels function in dorsal root ganglion neurons of rats.
作者信息
Lei Xiaolu, Chen Meiyun, Liu Xingfeng, Yan Yan, Li Xupeng, Gong Fei, Yu Deqian, Liu Xiaohong
机构信息
Key Laboratory of Anesthesia and Organ Protestion of Ministry of Education (In Cultivation), Zunyi Medical University, Zunyi 563000, China; Key Laboratory of Anesthesia and Organ Protection of Guizhou Province, Zunyi Medical University, Zunyi 563000, China; Key Laboratory of Brain Science, Guizhou Institution of Higher Education, Zunyi Medical University, Zunyi 563000, China.
Laboratory Department of Sanmen County People's Hospital, Zhejiang 317100, China.
出版信息
Brain Res Bull. 2025 Sep;229:111425. doi: 10.1016/j.brainresbull.2025.111425. Epub 2025 Jun 11.
Cannabinoid receptor (CBR) and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are both critically involved in pain hypersensitivity induced by nerve injury. Both CBR and HCN channels are expressed in sensory neurons of the dorsal root ganglia (DRG). Studies have shown that HCN channel function is regulated by cAMP-PKA signaling, and the activation of cannabinoid receptor 1 (CB1R) can inhibit cAMP-PKA activity. However, it remains unclear whether the function of HCN channels is regulated by CB1R activity in DRG. In this study, we investigated the effect of ACEA, a selective agonist for CB1R, on HCN channel expression and function in the DRG of rats with chronic constriction injury (CCI) of the sciatic nerve. Mechanical allodynia was assessed by measuring the mechanical withdrawal threshold (MWT). HCN1/ HCN2 channel expression and cAMP level in lumbar 4, 5 and 6 (L4-6) DRG were detected by Western blot analysis and ELISA, respectively. As a result, MWT decreased significantly in CCI rats. HCN1/ HCN2 channel expression and cAMP level increased in the ipsilateral L4-6 DRG after CCI operation. Notably, intrathecal injection of ACEA (0.05 mg/kg) significantly decreased mechanical allodynia, HCN1/ HCN2 expression, and cAMP level in CCI rats, and this effect was blocked by the CB1R antagonist AM251. On the other hand, I mediated by HCN channels of DRG neurons was recorded by whole-cell patch-clamp to evaluate HCN channel activity. In this assay, ACEA (1 μM) significantly reduced the amplitude of I in DRG neurons (P < 0.01), while pretreatment with AM251 blocked the inhibitory effect of ACEA on I (P < 0.01). In addition, 8-Br-cAMP, a PKA activator, could reverse the effect of ACEA on I in DRG neurons (P < 0.01), indicating that CB1R activation suppresses the function of HCN channels by decreasing cAMP-PKA activity. In conclusion, these findings suggest that CB1R activation can inhibit the function of HCN channels by decreasing cAMP-PKA activity, resulting in decreased excitability of primary sensory neurons.
大麻素受体（CBR）和超极化激活的环核苷酸门控（HCN）通道均与神经损伤诱导的疼痛超敏反应密切相关。CBR和HCN通道均在背根神经节（DRG）的感觉神经元中表达。研究表明，HCN通道功能受cAMP-PKA信号传导调节，大麻素受体1（CB1R）的激活可抑制cAMP-PKA活性。然而，尚不清楚DRG中HCN通道的功能是否受CB1R活性调节。在本研究中，我们研究了CB1R的选择性激动剂ACEA对坐骨神经慢性压迫损伤（CCI）大鼠DRG中HCN通道表达和功能的影响。通过测量机械缩足阈值（MWT）评估机械性异常性疼痛。分别通过蛋白质免疫印迹分析和酶联免疫吸附测定法检测腰4、5和6（L4-6）DRG中的HCN1/HCN2通道表达和cAMP水平。结果，CCI大鼠的MWT显著降低。CCI手术后，同侧L4-6 DRG中的HCN1/HCN2通道表达和cAMP水平升高。值得注意的是，鞘内注射ACEA（0.05 mg/kg）可显著降低CCI大鼠的机械性异常性疼痛、HCN1/HCN2表达和cAMP水平，且这种作用被CB1R拮抗剂AM251阻断。另一方面，通过全细胞膜片钳记录DRG神经元HCN通道介导的I电流以评估HCN通道活性。在该实验中，ACEA（1 μM）显著降低了DRG神经元中I电流的幅度（P < 0.01），而用AM251预处理可阻断ACEA对I电流的抑制作用（P < 0.01）。此外，PKA激活剂8-溴-cAMP可逆转ACEA对DRG神经元中I电流的作用（P < 0.01），表明CB1R激活通过降低cAMP-PKA活性抑制HCN通道功能。总之，这些发现表明CB1R激活可通过降低cAMP-PKA活性抑制HCN通道功能，导致初级感觉神经元兴奋性降低。
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