title: Astrocytes contribute to the effects of etomidate on synaptic transmission in rat primary somatosensory cortex.
abstract: Little is known about the mechanisms of unconsciousness induced by general anesthetics. Previous studies have shown that the primary somatosensory cortex (S1) is a sensitive region to a variety of intravenous general anesthetics. Etomidate is a widely used intravenous anesthetic that can influence synaptic transmission. Recently, there are some evidences suggesting that astrocytes, a type of glia cell, also contribute to information transmission in the brain, and modulate synaptic function by releasing neuroactive substances. However, it is unknown whether astrocytes influence the effects of etomidate on information transmission in S1 pyramidal neurons. In the present study, the role of astrocytes in etomidate-induced unconsciousness was investigated by using the whole-cell patch clamp technique. We observed etomidate at clinically relevant concentrations inhibited the spontaneous postsynaptic currents (sPSCs) of rat S1 pyramidal neurons in a concentration-dependent manner, and the EC50 value of etomidate for inhibiting sPSCs from the concentration-effect curve was 6.9μM. Furthermore, in the presence of fluorocitrate, a glia-selective metabolism inhibitor that blocks the aconitase enzyme, both the amplitude and frequency of sPSCs in rat S1 pyramidal neurons were reduced, and the inhibitory effects of etomidate on sPSCs amplitude was strengthened without affecting the effects of etomidate on frequency. From these data, we deduce that etomidate suppresses synaptic activity via presynaptic and postsynaptic components. Furthermore, astrocytes participate in synaptic transmission and influence the effects of etomidate on postsynaptic receptors. This study provides new insight into the role of astrocytes in etomidate-induced unconsciousness.
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Yang
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China; Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China; Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China.
authors.forename: You
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China.
authors.forename: Mao-Sheng
authors.initials: MS
authors.lastname: Xu
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China; Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Dalian Road, 563003 Zunyi, Guizhou, China. Electronic address: yutianzymc@sina.com.
authors.forename: Tian
authors.initials: T
authors.lastname: Yu
mesh_terms: D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000502:physiology*; D005045:Etomidate / Q000008:administration & dosage*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000187:drug effects* / Q000502:physiology*; D055366:Synaptic Potentials / Q000187:drug effects*; D014474:Unconsciousness / Q000139:chemically induced
chemical_list: D018686:Anesthetics, Intravenous; D005045:Etomidate
keywords: Astrocytes; Electrophysiology; Etomidate; Patch clamp; Primary somatosensory cortex; Spontaneous postsynaptic currents