Monitoring Astrocytic Ca2+ Activity in Freely Behaving Mice

Han Qin; Wenjing He; Chuanyan Yang; Jin Li; Tingliang Jian; Shanshan Liang; Tunan Chen; Hua Feng; Xiaowei Chen; Xiang Liao; Kuan Zhang

doi:10.3389/fncel.2020.603095

Monitoring Astrocytic Ca²⁺ Activity in Freely Behaving Mice

Front Cell Neurosci. 2020 Dec 3:14:603095. doi: 10.3389/fncel.2020.603095. eCollection 2020.

Authors

Han Qin^{1

2}, Wenjing He¹, Chuanyan Yang³, Jin Li¹, Tingliang Jian¹, Shanshan Liang¹, Tunan Chen³, Hua Feng³, Xiaowei Chen¹, Xiang Liao², Kuan Zhang¹

Affiliations

¹ Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, China.
² Center for Neurointelligence, School of Medicine, Chongqing University, Chongqing, China.
³ Department of Neurosurgery and Key Laboratory of Neurotrauma, Southwest Hospital, Third Military Medical University, Chongqing, China.

Abstract

Monitoring astrocytic Ca²⁺ activity is essential to understand the physiological and pathological roles of astrocytes in the brain. However, previous commonly used methods for studying astrocytic Ca²⁺ activities can be applied in only anesthetized or head-fixed animals, which significantly affects in vivo astrocytic Ca²⁺ dynamics. In the current study, we combined optic fiber recordings with genetically encoded Ca²⁺ indicators (GECIs) to monitor astrocytic activity in freely behaving mice. This approach enabled selective and reliable measurement of astrocytic Ca²⁺ activity, which was verified by the astrocyte-specific labeling of GECIs and few movement artifacts. Additionally, astrocytic Ca²⁺ activities induced by locomotion or footshock were stably recorded in the cortices and hippocampi of freely behaving mice. Furthermore, this method allowed for the longitudinal study of astrocytic activities over several weeks. This work provides a powerful approach to record astrocytic activity selectively, stably, and chronically in freely behaving mice.

Keywords: Ca2+ signals; astrocytes; cortex; freely behaving mice; genetically encoded Ca2+ indicators; hippocampus; optic fiber.