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Effects of Etomidate on GABAergic and Glutamatergic Transmission in Rat Thalamocortical Slices

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Abstract

Although accumulative evidence indicates that the thalamocortical system is an important target for general anesthetics, the underlying mechanisms of anesthetic action on thalamocortical neurotransmission are not fully understood. The aim of the study is to explore the action of etomidate on glutamatergic and GABAergic transmission in rat thalamocortical slices by using whole cell patch-clamp recording. We found that etomidate mainly prolonged the decay time of spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs), without changing the frequency. Furthermore, etomidate not only prolonged the decay time of miniature inhibitory postsynaptic currents (mIPSCs) but also increased the amplitude. On the other hand, etomidate significantly decreased the frequency of spontaneous glutamatergic excitatory postsynaptic currents (sEPSCs), without altering the amplitude or decay time in the absence of bicuculline. When GABAA receptors were blocked using bicuculline, the effects of etomidate on sEPSCs were mostly eliminated. These results suggest that etomidate enhances GABAergic transmission mainly through postsynaptic mechanism in thalamocortical neuronal network. Etomidate attenuates glutamatergic transmission predominantly through presynaptic action and requires presynaptic GABAA receptors involvement.

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Abbreviations

GABA:

γ-Aminobutyric acid

ACSF:

Artificial cerebrospinal fluid

S1BF:

The primary somatosensory barrel cortex

VPM:

The ventral posteromedial nucleus

sEPSCs:

Spontaneous excitatory postsynaptic currents

sIPSCs:

Spontaneous inhibitory postsynaptic currents

mEPSCs:

Miniature excitatory postsynaptic currents

mIPSCs:

Miniature inhibitory postsynaptic currents

VB:

The ventrobasal complex

RTN:

The reticular nucleus

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Acknowledgments

Supported by grants from the National Natural Science Foundation of China (NSFC, Grant No. 81060266 and 81571026). Thanks for Junwei Zeng (Zunyi Medical College, Zunyi, China) for carefully reading an early version of the manuscript.

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    Authors and Affiliations

    1. Department of Critical Care Medicine, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China

      Bao Fu

    2. Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China

      Yuan Wang

    3. Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian road 149, Zunyi, 563000, Guizhou, China

      Hao Yang & Tian Yu

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    1. Bao Fu
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    Correspondence to Tian Yu.

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    Bao Fu and Yuan Wang have contributed to the work equally and should be regarded as co-first authors.

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    Fu, B., Wang, Y., Yang, H. et al. Effects of Etomidate on GABAergic and Glutamatergic Transmission in Rat Thalamocortical Slices. Neurochem Res 41, 3181–3191 (2016). https://doi.org/10.1007/s11064-016-2042-6

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