title: Clozapine functions through the prefrontal cortex serotonin 1A receptor to heighten neuronal activity via calmodulin kinase II-NMDA receptor interactions.
abstract: Aberrant dopamine release in the prefrontal cortex (PFC) is believed to underlie schizophrenia, but the mechanistic pathway through which a widely used antipsychotic, clozapine (Clz), evokes neurotransmitter-releasing electrical stimulation is unclear. We analyzed Clz-evoked regulation of neuronal activity in the PFC by stimulating axons in layers IV and V and recording the electrical effect in the post-synaptic pyramidal cells of layers II and III. We observed a Clz-evoked increase in population spike (PS), which was mediated by serotonin 1A receptor (5-HT(1A)-R), phospholipase Cβ, and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Immunoblotting demonstrated that the Clz-activation of CaMKII was 5-HT(1A)-R-mediated. Intriguingly, the NMDA receptor (NMDA-R) antagonist (±)2-amino-5-phosphonovaleric acid (APV) eliminated the Clz-mediated increase in PS, suggesting that the 5-HT(1A)-R, NMDA-R and CaMKII form a synergistic triad, which boosts excitatory post-synaptic potential (EPSP), thereby enhancing PS. In corroboration, Clz as well as NMDA augmented field EPSP (fEPSP), and WAY100635 (a 5-HT(1A)-R antagonist), APV, and a CaMKII inhibitor eliminated this increase. As previously shown, CaMKII binds to the NMDA-R 2B (NR2B) subunit to become constitutively active, thereby inducing α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor recruitment to the post-synaptic membrane and an increase in fEPSP. Co-immunoprecipitation demonstrated that Clz potentiates interactions among CaMKII, NR2B, and 5-HT(1A)-R, possibly in the membrane rafts of the post-synaptic density (PSD), because pretreatment with methyl-β-cyclodextrin (MCD), an agent that disrupts rafts, inhibited both co-immunoprecipitation as well as fEPSP. In summary, Clz functions in the PFC by orchestrating a synergism among 5-HT(1A)-R, CaMKII, and NMDA-R, which augments excitability in the PFC neurons of layers II/III.
authors: CSI/IBR Center for Developmental Neuroscience, The College of Staten Island, Staten Island, New York 10314, USA.
authors: Sudarshana
authors: S
authors: Purkayastha
authors: Jason
authors: J
authors: Ford
authors: Baishali
authors: B
authors: Kanjilal
authors: Souleymane
authors: S
authors: Diallo
authors: Joseph
authors: J
authors: Del Rosario Inigo
authors: Lorenz
authors: L
authors: Neuwirth
authors: Abdeslem
authors: A
authors: El Idrissi
authors: Zaghloul
authors: Z
authors: Ahmed
authors: Andrzej
authors: A
authors: Wieraszko
authors: Efrain C
authors: EC
authors: Azmitia
authors: Probal
authors: P
authors: Banerjee
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D003024:Clozapine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009474:Neurons / Q000187:drug effects*; D017397:Prefrontal Cortex / Q000166:cytology* / Q000378:metabolism; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D018490:Serotonin Agents / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D018683:Excitatory Amino Acid Agents; D016194:Receptors, N-Methyl-D-Aspartate; D018490:Serotonin Agents; D044282:Receptor, Serotonin, 5-HT1A; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D003024:Clozapine