title: Low Doses of Ethanol Enhance LTD-like Plasticity in Human Motor Cortex.
abstract: Humans liberally use ethanol for its facilitating effects on social interactions but its effects on central nervous system function remain underexplored. We have recently described that very low doses of ethanol abolish long-term potentiation (LTP)-like plasticity in human cortex, most likely through enhancement of tonic inhibition [Lücke et al, 2014, Neuropsychopharmacology 39:1508-18]. Here, we studied the effects of low-dose ethanol on long-term depression (LTD)-like plasticity. LTD-like plasticity was induced in human motor cortex by paired associative transcranial magnetic stimulation (PASLTD), and measured as decreases of motor evoked potential input-output curve (IO-curve). In addition, sedation was measured by decreases in saccade peak velocity (SPV). Ethanol in two low doses (EtOH<10mM, EtOH<20mM) was compared to single oral doses of alprazolam (APZ, 1mg) a classical benzodiazepine, and zolpidem (ZLP, 10 mg), a non-benzodiazepine hypnotic, in a double-blinded randomized placebo-controlled crossover design in ten healthy human subjects. EtOH<10mM and EtOH<20mM but not APZ or ZLP enhanced the PASLTD-induced LTD-like plasticity, while APZ and ZLP but not EtOH<10mM or EtOH<20mM decreased SPV. Non-sedating low doses of ethanol, easily reached during social drinking, enhance LTD-like plasticity in human cortex. This effect is most likely explained by the activation of extrasynaptic α4-subunit containing gamma-aminobutyric type A receptors by low-dose EtOH, resulting in increased tonic inhibition. Findings may stimulate cellular research on the role of tonic inhibition in regulating excitability and plasticity of cortical neuronal networks.
authors.affiliation: Department of Neurology, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Fuhl
authors.affiliation: Department of Neurology, Goethe-University, Frankfurt am Main, Germany.|Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Müller-Dahlhaus
authors.affiliation: Department of Neurology, Goethe-University, Frankfurt am Main, Germany.|Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lücke
authors.affiliation: Department of Forensic Toxicology, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Stefan W
authors.identifier: http://orcid.org/0000-0002-1774-3201
authors.initials: SW
authors.lastname: Toennes
authors.affiliation: Department of Neurology, Goethe-University, Frankfurt am Main, Germany.|Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany.
authors.forename: Ulf
authors.identifier: http://orcid.org/0000-0001-8372-3615
authors.initials: U
authors.lastname: Ziemann
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000525:Alprazolam / Q000008:administration & dosage / Q000097:blood / Q000652:urine; D002492:Central Nervous System Depressants / Q000008:administration & dosage* / Q000097:blood / Q000652:urine; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004576:Electromyography; D000431:Ethanol / Q000008:administration & dosage* / Q000097:blood / Q000652:urine; D019054:Evoked Potentials, Motor / Q000187:drug effects; D006225:Hand / Q000502:physiology; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000097:blood / Q000652:urine; D009044:Motor Cortex / Q000187:drug effects* / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects* / Q000502:physiology*; D011725:Pyridines / Q000008:administration & dosage / Q000097:blood / Q000652:urine; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult; D000077334:Zolpidem
chemical_list: D002492:Central Nervous System Depressants; D006993:Hypnotics and Sedatives; D011725:Pyridines; D000431:Ethanol; D000077334:Zolpidem; D000525:Alprazolam