title: GABAergic antagonists block the inhibitory effects of serotonin in the lateral amygdala: a mechanism for modulation of sensory inputs related to fear conditioning.
abstract: Neurons in the lateral amygdala (LA) receive glutamatergic sensory input from the auditory thalamus and auditory cortex, and these inputs can be modulated by serotonin (5-HT). In the present study, we examined whether serotonergic inhibition of glutamatatergic excitation in the LA occurs via activation of GABAergic interneurons. Single-unit extracellular activity in the LA was recorded in response to iontophoretically applied glutamate. Concurrent application of 5-HT reduced the number of glutamate-evoked action potentials in the majority of neurons tested. GABA antagonists were then iontophoresed with both glutamate and 5-HT. Of the neurons that were inhibited by 5-HT, concurrent application of the GABA antagonists significantly reversed this effect. Application of the GABA antagonists alone had little or no effect on basal neuronal activity. We conclude that the 5-HT-induced inhibition of glutamatergic activity occurs in part through activation of serotonergic receptors on GABAergic interneurons.
authors.affiliation: Center for Neural Science, New York University, New York, New York 10003, USA.
authors.forename: G E
authors.initials: GE
authors.lastname: Stutzmann
authors.forename: J E
authors.initials: JE
authors.lastname: LeDoux
mesh_terms: D000200:Action Potentials; D000679:Amygdala / Q000166:cytology / Q000502:physiology*; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology; D005239:Fear / Q000502:physiology; D018756:GABA Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D018698:Glutamic Acid / Q000008:administration & dosage / Q000494:pharmacology; D007395:Interneurons / Q000502:physiology; D007478:Iontophoresis; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D018756:GABA Antagonists; D012701:Serotonin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid