Ethanol inhibits histaminergic neurons in mouse tuberomammillary nucleus slices via potentiating GABAergic transmission onto the neurons at both pre- and postsynaptic sites  

作　　者：Yu SUN Shi-yu JIANG Jian NI Yan-jia LUO Chang-rui CHEN Zong-yuan HONG Yuchio YANAGAWA Wei-min QU Lu WANG Zhi-li HUANG 

机构地区：[1]Department of Pharmacology, State Key Laboratory of Medical Neurobiology, and Shanghai Key Laboratory of Bioactive Small Molecules, School of Basic Medical Sciences Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China [2]Laboratory of Quantitative Pharmacology, Department of Pharmacology, Wannan Medical College, Wuhu 241002, China [3]Department of Genetic and Behavioral Neuroscience, Gunma Utliversity Graduate School of Medicine, Maebashi 371-8511, Japan

出　　处：《Acta Pharmacologica Sinica》2016年第10期1325-1336,共12页中国药理学报（英文版）

基　　金：Acknowledgements This work was supported in part by grants-in-aid for scientific research from the National Basic Research Program of China （No 2015CB856401）, the National Natural Science Foundation of China （No 31530035, 31571103, 81420108015, 31471064, 31421091, 81171255, and 31271164）, the Shanghai Committee of Science and Technology （No 14JC1400900 and 13dz2260700）, and the Key Laboratory Program of the Education Commission of Shanghai Municipality （No ZDSYS14005）.

摘　　要：Aim： Ethanol, one of the most frequently used and abused substances in our society, has a profound impact on sedation. However, the neuronal mechanisms underlying its sedative effect remain unclear. In this study, we investigated the effects of ethanol on histaminergic neurons in the tuberomammillary nucleus （TMN）, a brain region thought to be critical for wakefulness. Methods： Coronal brain slices （250 pm thick） containing the TMN were prepared from GAD67-GFP knock-in mice. GAD67-GFP was used to identify histaminergic neurons in the TMN. The spontaneous firing and membrane potential of histaminergic neurons, and GABAergic transmission onto these neurons were recorded using whole-cell patch-clamp recordings. Drugs were applied through superfusion.Results： Histaminergic and GAD67-expressing neurons in the TMN of GAD67-GFP mice were highly co-localized. TMN GFP-positive neurons exhibited a regular spontaneous discharge at a rate of 2-4 Hz without burst firing. Brief superfusion of ethanol （64, 190, and 560 mmol/L） dose-dependently and reversibly suppressed the spontaneous firing of the neurons in the TMN; when synaptic transmission was blocked by tetrodotoxin （1 μmol/L）, ethanol caused hyperpolarization of the membrane potential. Furthermore, superfusion of ethanol markedly increased the frequency and amplitude of spontaneous and miniature inhibitory postsynaptic currents （slPSCs and mlPSCs）, which were abolished in the presence of the GABAA receptor antagonist bicuculline （20 μmol/L）. Finally, ethanolmediated enhancement of slPSCs and mlPSCs was significantly attenuated when the slices were pretreated with the GABAB agonist baclofen （30 μmoVL）.Conclusion： Ethanol inhibits the excitability of histaminergic neurons in mouse TMN slices, possibly via potentiating GABAergic transmission onto the neurons at both pre- and postsynaptic sites.Aim： Ethanol, one of the most frequently used and abused substances in our society, has a profound impact on sedation. However, the neuronal mechanisms underlying its sedative effect remain unclear. In this study, we investigated the effects of ethanol on histaminergic neurons in the tuberomammillary nucleus （TMN）, a brain region thought to be critical for wakefulness. Methods： Coronal brain slices （250 pm thick） containing the TMN were prepared from GAD67-GFP knock-in mice. GAD67-GFP was used to identify histaminergic neurons in the TMN. The spontaneous firing and membrane potential of histaminergic neurons, and GABAergic transmission onto these neurons were recorded using whole-cell patch-clamp recordings. Drugs were applied through superfusion.Results： Histaminergic and GAD67-expressing neurons in the TMN of GAD67-GFP mice were highly co-localized. TMN GFP-positive neurons exhibited a regular spontaneous discharge at a rate of 2-4 Hz without burst firing. Brief superfusion of ethanol （64, 190, and 560 mmol/L） dose-dependently and reversibly suppressed the spontaneous firing of the neurons in the TMN; when synaptic transmission was blocked by tetrodotoxin （1 μmol/L）, ethanol caused hyperpolarization of the membrane potential. Furthermore, superfusion of ethanol markedly increased the frequency and amplitude of spontaneous and miniature inhibitory postsynaptic currents （slPSCs and mlPSCs）, which were abolished in the presence of the GABAA receptor antagonist bicuculline （20 μmol/L）. Finally, ethanolmediated enhancement of slPSCs and mlPSCs was significantly attenuated when the slices were pretreated with the GABAB agonist baclofen （30 μmoVL）.Conclusion： Ethanol inhibits the excitability of histaminergic neurons in mouse TMN slices, possibly via potentiating GABAergic transmission onto the neurons at both pre- and postsynaptic sites.

关 键 词：ETHANOL tuberomammillary nucleus histaminergic neurons GABA receptor IPSCs BICUCULLINE BACLOFEN TETRODOTOXIN 

分 类 号：R[医药卫生]