• Mengfan He, Hanxi Wan, Peilin Cong, Xinyang Li, Chun Cheng, Xinwei Huang, Qian Zhang, Huanghui Wu, Li Tian, Ke Xu, and Lize Xiong.
• Shanghai Key Laboratory of Anaesthesiology and Brain Functional Modulation, Translational Research Institute of Brain and Brain-Like Intelligence, Clinical Research Centre for Anaesthesiology and Perioperative Medicine, Department of Anaesthesiology and Perioperative Medicine, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China.
• Br J Anaesth. 2024 Nov 26.

BackgroundAnaesthesia has been shown to impair social functioning, but the underlying mechanisms remain largely unknown. The volatile anaesthetic isoflurane potentially disrupts the methionine cycle and trans-sulphuration pathway, contributing to social deficits. Cystathionine-β-synthase (CBS), a key enzyme in this pathway, might be targeted by isoflurane. We investigated the CBS-isoflurane interaction and its role in neuronal function and social behaviour.MethodsMice aged 3-15 months were anaesthetised with 2 vol% isoflurane for 2 h, and social behaviours were tested 24 h after exposure. Alterations in neuronal activity were assessed using electrophysiological analysis in vivo. Pharmacological activators (S-adenosylmethionine [SAM]) or inhibitors (amino-oxyacetic acid [AOAA]), and adeno-associated virus (AAV) were used to modulate CBS activity. The binding site of isoflurane on CBS was determined using X-ray crystallography. A novel transgenic model with a point mutation knock-in was constructed to eliminate the CBS-isoflurane interaction.ResultsIsoflurane inhibited CBS activity (by 0.35-fold [0.07] vs 1.00-fold [0.05]; P<0.001), leading to neuronal hypoactivity in the anterior cingulate cortex (ACC) and social impairments in adult and elderly mice. SAM, AOAA, and AAV interventions demonstrated a causal link. Structural and functional analysis identified the lysine 273 (K273) in CBS to be involved in isoflurane inhibition. CBS K273A knock-in mice exhibited increased CBS activity compared with wild-type littermates after isoflurane exposure (2.2-fold [0.22] vs 1.0-fold [0.28]; P<0.001), with successful alleviation of ACC neuronal hypoactivity and social dysfunction.ConclusionsThese findings reveal a crucial role for CBS inhibition by isoflurane in anaesthesia-induced social impairment.Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.

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