Chen Rong, Li Meng, Ding Mingxing
College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
College of Animal Science and Technology, Tarim University, Alar, Xinjiang, 843300, China.
Heliyon. 2024 Oct 30;10(21):e39992. doi: 10.1016/j.heliyon.2024.e39992. eCollection 2024 Nov 15.
Inflammatory pain, an important form of common pain, negatively influences the quality of life. Pathway-selective optogenetic control is a popular tool in neuronal function research; however, attempts to modulate rodent behavior using pathway-selective optogenetics remain unverified. We developed a methodology for pathway-selective optogenetics in rats, focusing on the delivery of recombinant adeno-associated virus (rAAV) containing channelrhodopsin-2 (ChR2) injected at the "Zusanli" acupoints to the dorsal root ganglia (DRG) and toes, which is a part of the complex neuron network. Optogenetic stimulation of gamma-aminobutyric acid (GABA) projections to the "Zusanli" acupoints delivered several rAAV9-GAD1-ChR2-mcherry particles to the spinal cord horn (SCDH) and DRG and few rAAV9-GAD1-ChR2-mcherry particles to toes, thereby evoking an analgesic effect in complete Freund's adjuvant (CFA) rats similar to those of acupuncture. Furthermore, blue light stimulation (LED) and electroacupuncture (EA) reduced inflammatory pain in CFA rats, as evidenced by the changes in the paw edema, paw withdrawal latency (PWL), and paw withdrawal threshold (PWT) values. Further exploration of the mechanisms underlying this phenomenon revealed that optogenetic stimulation upregulates the decarboxylase-65 (GAD65) and decarboxylase-67 (GAD67) protein levels and downregulates the levels of GABA transporter-1 (GAT1) and GABA transporter-3 (GAT3) to alleviate inflammatory pain. The activation of the p38 mitogen-activated protein kinases (MAPK) and Wnt signal transduction pathways decreased the release of interleukin 6 (IL-6), interleukin 10 (IL-10), and tumor necrosis factor-α (TNFα). These findings indicate that optogenetic stimulation of the "Zusanli" acupoint alleviated inflammatory pain.
炎性疼痛是常见疼痛的一种重要形式,会对生活质量产生负面影响。通路选择性光遗传学控制是神经元功能研究中的一种常用工具;然而,利用通路选择性光遗传学调节啮齿动物行为的尝试仍未得到验证。我们开发了一种大鼠通路选择性光遗传学方法,重点是将含有通道视紫红质-2(ChR2)的重组腺相关病毒(rAAV)注射到“足三里”穴位,然后输送至背根神经节(DRG)和脚趾,这是复杂神经元网络的一部分。对投射到“足三里”穴位的γ-氨基丁酸(GABA)进行光遗传学刺激,将多个rAAV9-GAD1-ChR2-mcherry颗粒输送至脊髓背角(SCDH)和DRG,而输送至脚趾的rAAV9-GAD1-ChR2-mcherry颗粒较少,从而在完全弗氏佐剂(CFA)大鼠中诱发与针刺类似的镇痛效果。此外,蓝光刺激(LED)和电针(EA)减轻了CFA大鼠的炎性疼痛,爪部水肿、爪部撤离潜伏期(PWL)和爪部撤离阈值(PWT)值的变化证明了这一点。对这一现象潜在机制的进一步探索表明,光遗传学刺激上调了脱羧酶-65(GAD65)和脱羧酶-67(GAD67)的蛋白水平,下调了GABA转运体-1(GAT1)和GABA转运体-3(GAT3)的水平,从而减轻炎性疼痛。p38丝裂原活化蛋白激酶(MAPK)和Wnt信号转导通路的激活降低了白细胞介素6(IL-6)、白细胞介素10(IL-10)和肿瘤坏死因子-α(TNFα)的释放。这些发现表明,对“足三里”穴位进行光遗传学刺激可减轻炎性疼痛。