Cortical 5-hydroxytryptamine2A-receptor mediated excitatory synaptic currents in the rat following repeated daily fluoxetine administration.
Down-regulation of 5-hydroxytryptamine(2A) (5-HT(2A)) receptors has been a consistent effect induced by most antidepressant drugs. The evidence for down-regulation of 5-HT(2A) receptor binding following subchronic treatment with fluoxetine and other selective serotonin reuptake inhibitors (SSRIs) is mixed. The question of 5-HT(2A) receptor sensitivity during chronic administration of antidepressants is important since activation of 5-HT(2A) receptors is associated with impulsivity. Continued activation of 5-HT(2A) receptors may functionally oppose activation of other non-5-HT(2A) receptors in the prefrontal cortex associated with the clinical efficacy of SSRI treatment. Therefore, the effects of repeated daily administration of fluoxetine (10 mg/kg, i.p. x 3 weeks) on pharmacologically characterized electrophysiological response mediated by 5-HT(2A) receptor activation, 5-HT-induced excitatory postsynaptic currents (EPSCs), in rat prefrontal cortical slices was examined. The concentration-response curve for 5-HT-induced EPSCs was unchanged following subchronic fluoxetine treatment. This subchronic fluoxetine treatment failed to modify electrophysiological responses to AMPA in layer V pyramidal cells as well. These findings would be consistent with the hypothesis that blockade of 5-HT(2A) receptors may enhance the effects of SSRIs or serotonin/norepinephrine reuptake inhibitors (SNRIs).
Marek
Gerard J
GJ
Discovery Biology, Eli Lilly and Company, Lilly Corporate Center, Mail Drop 0510, Indianapolis, IN 46285 USA. gerard_j_marek@lilly.com
D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D005473:Fluoxetine / Q000008:administration & dosage*; D066298:In Vitro Techniques; D008297:Male; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage*
D005473:Fluoxetine; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors