Gα q signaling in primary sensory neurons shifts opioid analgesia to NMDA receptor–driven tolerance and hyperalgesia

作者：Daozhong Jin, Hong Chen, Menghua Zhou, Yuying Huang, Shao-Rui Chen, Hui‐Lin Pan · 发表于：Science Signaling · 年份：2025 · DOI：10.1126/scisignal.adu8839 · 被引用次数：4 · 研究领域：Pain Mechanisms and Treatments、Neuroscience and Neuropharmacology Research、Neuropeptides and Animal Physiology

Opioids relieve pain by activating μ-opioid receptors (MORs), which inhibit communication between pain-sensing neurons (nociceptors) and the spinal cord. However, prolonged opioid use can paradoxically lead to increased pain sensitivity (hyperalgesia) and reduced analgesic efficacy (tolerance), partly because of the activation of NMDA-type glutamate receptors (NMDARs) at the central terminals of primary sensory neurons in the spinal cord. Here, we identified a critical role for the G protein Gα q in this paradox. Pharmacological inhibition of Gα q in rats reversed morphine-induced increases in NMDAR phosphorylation, synaptic trafficking, and activity at sensory neuron terminals and reduced morphine-induced excitatory nociceptive input to spinal dorsal horn neurons. Morphine enhanced Gα q coupling specifically to metabotropic glutamate receptor 5 (mGluR5) dimers in the spinal cord. Furthermore, targeted knockdown of Gα q in dorsal root ganglion neurons in mice normalized NMDAR-related changes and prevented NMDAR-mediated synaptic potentiation triggered by MOR activation. In addition, either pharmacological or genetic disruption of Gα q signaling enhanced morphine’s analgesic effects while reducing hyperalgesia and tolerance. These findings reveal that Gα q signaling contributes to opioid-induced NMDAR hyperactivity at nociceptor central terminals by promoting MOR-mGluR5 cross-talk. Targeting this pathway may improve the safety and efficacy of opioid-based pain management.