title: Enhanced retention in the passive-avoidance task by 5-HT(1A) receptor blockade is not associated with increased activity of the central nucleus of the amygdala.
abstract: The effect of blockade of 5-HT1A receptors was investigated on (1). retention in a mildly aversive passive-avoidance task, and (2). spontaneous single-unit activity of central nucleus of the amygdala (CeA) neurons, a brain site implicated in modulation of retention. Systemic administration of the selective 5-HT1A antagonist NAN-190 immediately after training markedly-and dose-dependently-facilitated retention in the passive-avoidance task; enhanced retention was time-dependent and was not attributable to variations in wattages of shock received by animals. Systemic administration of NAN-190 had mixed effects on spontaneous single-unit activity of CeA neurons recorded extracellularly in vivo; microiontophoretic application of 5-HT, in contrast, consistently and potently suppressed CeA activity. The present findings-that 5-HT1A receptor blockade by NAN-190 (1). enhances retention in the passive-avoidance task, and (2). does not consistently increase spontaneous neuronal activity of the CeA-provide evidence that a serotonergic system tonically inhibits modulation of retention in the passive-avoidance task through activation of the 5-HT1A receptor subtype at brain sites located outside the CeA.
authors.affiliation: Department of Psychology, Swarthmore College, Swarthmore, Pennsylvania 19081, USA. Aschnei1@Swarthmore.edu
authors.forename: Allen M
authors.initials: AM
authors.lastname: Schneider
authors.forename: Emily
authors.initials: E
authors.lastname: Wilkins
authors.forename: Aaron
authors.initials: A
authors.lastname: Firestone
authors.forename: E Carr
authors.initials: EC
authors.lastname: Everbach
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Naylor
authors.forename: Peter E
authors.initials: PE
authors.lastname: Simson
mesh_terms: D000200:Action Potentials; D000679:Amygdala / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D008297:Male; D010879:Piperazines / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D020318:Rats, Long-Evans; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D012153:Retention, Psychology / Q000187:drug effects* / Q000502:physiology*; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists / Q000494:pharmacology*
chemical_list: D010879:Piperazines; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists; D044282:Receptor, Serotonin, 5-HT1A; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine