Reactive astrocytes mediate postoperative surgery-induced anxiety through modulation of GABAergic signalling in the zona incerta of mice

Abstract

Background: Surgery can induce severe neuroinflammation and negative emotional symptoms, such as anxiety-like behaviour. We studied whether reactive astrocytes in the zona incerta (ZI) mediate surgery-induced anxiety in mice.

Methods: Laparotomy under isoflurane 1.5 vol% was used as a model in adult mice. The role of the ZI in surgery-induced anxiety was evaluated by behavioural tests, optical fibre recordings of neuronal activity, in vivo electrophysiological recordings, chemogenetics, and optogenetics.

Results: Operative mice showed increased anxiety-like behaviour. Immunostaining and optical calcium recording revealed that astrocytes were abnormally activated in the ZI. Pharmacologic (F_{3, 15}=5.837, P=0.044) or genetic manipulation (open field test: t_7.41=3.66, P=0.007; elevated plus maze [EPM]: t₁₀=2.70, P=0.022) of astrocyte activation in the ZI relieved anxiety-like behaviour in surgery-treated mice. Compared with the sham group, the surgery group showed increased extrasynaptic GABA concentrations and decreased GABA transporter-3 (GAT-3) expression, and inactivation of GABAergic neurones in the ZI. Upregulating GAT-3 in ZI astrocytes (OFT: t_10.83=2.91, P=0.014; EPM: t_9.15=3.55, P=0.006) or activating the GABAergic projection from ZI to the median raphe nucleus (ZI^GABA→median raphe nucleus) (EPM: entries: F_{1, 24}=3.45, P=0.027; time: F_{1, 25}=4.07, P=0.043) ameliorated surgery-induced anxiety.

Conclusions: Reactive astrocytes in the zona incerta mediate surgery-induced anxiety, possibly by regulating GAT-3-mediated GABA homeostasis and inactivating ZI^GABA→median raphe nucleus projections in mice.

Keywords: GABA transporter-3; anxiety; astrocyte; median raphe nucleus; surgery; zona incerta.