title: Histamine excites GABAergic cells in the rat substantia nigra and ventral tegmental area in vitro.
abstract: We have investigated the effect of histamine (HA) on spontaneous firing of dopaminergic (DA) and GABAergic neurons in the substantia nigra (SN) and the ventral tegmental area (VTA) of the rat in vitro. Single-unit extracellular recordings were obtained and drugs were bath applied. In both regions application of HA (10 and 100 microM) did not affect the firing frequency of DAergic cells, but increased the firing of GABAergic neurons. The histamine-induced excitation was blocked by the H(1) receptor antagonist mepyramine (1 microM), but was unaffected by application of the H(2) antagonist cimetidine (50 microM) or the H(3) antagonist thioperamide (10 microM). Our results suggest that histamine does not directly inhibit dopaminergic neurons in SN and VTA, but rather that this inhibition is mediated through histamine-induced excitation of GABAergic neurons.
authors.affiliation: Institute for Neurophysiology, Heinrich Heine University, D-40001, Duesseldorf, Germany. tatiana.korotkova@uni-duesseldorf.de
authors.forename: Tatiana M
authors.initials: TM
authors.lastname: Korotkova
authors.forename: Helmut L
authors.initials: HL
authors.lastname: Haas
authors.forename: Ritchie E
authors.initials: RE
authors.lastname: Brown
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D004298:Dopamine / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018756:GABA Antagonists / Q000494:pharmacology; D006632:Histamine / Q000378:metabolism* / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018079:Receptors, GABA / Q000187:drug effects / Q000378:metabolism; D011968:Receptors, Histamine / Q000187:drug effects / Q000378:metabolism; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D017557:Ventral Tegmental Area / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D018756:GABA Antagonists; D006633:Histamine Antagonists; D018079:Receptors, GABA; D011968:Receptors, Histamine; D005680:gamma-Aminobutyric Acid; D006632:Histamine; D004298:Dopamine