title: Ethanol inhibits histaminergic neurons in mouse tuberomammillary nucleus slices via potentiating GABAergic transmission onto the neurons at both pre- and postsynaptic sites.
abstract: OBJECTIVE
  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 μm 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 (sIPSCs and mIPSCs), which were abolished in the presence of the GABAAreceptor antagonist bicuculline (20 μmol/L). Finally, ethanol-mediated enhancement of sIPSCs and mIPSCs was significantly attenuated when the slices were pretreated with the GABABagonist baclofen (30 μmol/L).
  
  
  CONCLUSIONS
  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.
authors: 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.
authors: Yu
authors: Y
authors: Sun
authors: 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.|Laboratory of Quantitative Pharmacology, Department of Pharmacology, Wannan Medical College, Wuhu 241002, China.
authors: Shi-Yu
authors: SY
authors: Jiang
authors: 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.
authors: Jian
authors: J
authors: Ni
authors: 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.
authors: Yan-Jia
authors: YJ
authors: Luo
authors: 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.
authors: Chang-Rui
authors: CR
authors: Chen
authors: Laboratory of Quantitative Pharmacology, Department of Pharmacology, Wannan Medical College, Wuhu 241002, China.
authors: Zong-Yuan
authors: ZY
authors: Hong
authors: Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi 371-8511, Japan.
authors: Yuchio
authors: Y
authors: Yanagawa
authors: 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.
authors: Wei-Min
authors: WM
authors: Qu
authors: 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.
authors: Lu
authors: L
authors: Wang
authors: 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.
authors: Zhi-Li
authors: ZL
authors: Huang
mesh_terms: D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D018755:GABA Agonists / Q000494:pharmacology; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D006632:Histamine / Q000378:metabolism*; D007026:Hypothalamic Area, Lateral / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D055369:Miniature Postsynaptic Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D011963:Receptors, GABA-A / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*
chemical_list: D018755:GABA Agonists; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D000431:Ethanol; D006632:Histamine; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D001418:Baclofen