• Yu Zou, Xin He, Zhiwen Ye, Zhengyiqi Li, Qulian Guo, Wangyuan Zou, and Qianyi Peng.
• Department of Anesthesia, Xiangya Hospital Central South University, Changsha, Hunan Province, China.
• Reg Anesth Pain Med. 2024 Jan 17.

IntroductionLocal anesthetic-induced neurotoxicity contributes to perioperative nerve damage; however, the underlying mechanisms remain unclear. Here, we investigated the role of the paraventricular thalamus (PVT)-nucleus accumbens (NAc) projections in neurotoxicity induced by ropivacaine, a local anesthetic agent.MethodsRopivacaine (58 mg/kg, intraperitoneal administration) was used to construct the local anesthetic systemic toxicity (LAST) mice model. We first identified neural projections from the PVT to the NAc through the expression of a retrograde tracer and virus. The inhibitory viruses (rAAV-EF1α-DIO-hm4D(Gi)-mCherry-WPREs: AAV2/retro and rAAV-CaMKII-CRE-WPRE-hGh: AAV2/9) were injected into the mice model to assess the effects of the specific inhibition of the PVT-NAc pathway on neurological behaviors in the presence of clozapine-N-oxide. The inhibition of the PVT-NAc pathway was evaluated by immunofluorescence staining of c-Fos-positive neurons and Ca2+ signals in CaMKIIa neurons.ResultsWe successfully identified a circuit connecting the PVT and NAc in C57BL/6 mice. Ropivacaine administration induced the activation of the PVT-NAc pathway and seizures. Specific inhibition of NAc-projecting CaMKII neurons in the PVT was sufficient to inhibit the neuronal activity in the NAc, which subsequently decreased ropivacaine-induced neurotoxicity.ConclusionThese results reveal the presence of a dedicated PVT-NAc circuit that regulates local anesthetic-induced neurotoxicity and provide a potential mechanistic explanation for the treatment and prevention of LAST.© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.

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