Synaptic localization of adrenergic disinhibition in the rat hippocampus.
Norepinephrine is an endogenous neurotransmitter that reduces synaptic inhibition onto pyramidal neurons in the hippocampus by an action at an alpha-adrenergic receptor. The physiological mechanism of this disinhibition was previously not known, except that it occurred at a site presynaptic to the inhibited pyramidal cell. In this paper we present evidence that adrenergic disinhibition is restricted to the early phase of the evoked inhibitory postsynaptic potential in area CA1 of the hippocampus. The locus of disinhibition does not appear to reside in the interneuronal terminal, axon, or cell body. Instead, adrenergic agonists appear to reduce evoked synaptic inhibition by depressing excitatory synapses that activate the interneuron.
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Department of Molecular and Cellular Physiology, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, California 94305-5426.
Cohen
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Madison
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D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010852:Picrotoxin / Q000494:pharmacology; D011712:Pyramidal Tracts / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D001418:Baclofen; D004744:Enkephalin, Methionine; D004837:Epinephrine; D007545:Isoproterenol; D009638:Norepinephrine; D010852:Picrotoxin; D011942:Receptors, Adrenergic, alpha; C022118:enkephalinamide-Met, Ala(2)-