To test this possibility, the Clz-evoked PS was studied in the presence of the D2 agonist PPHT (100 M). the 5-HT1A-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-HT1A-R antagonist), APV, and a CaMKII inhibitor eliminated this increase. As previously shown, CaMKII binds to the NMDA-R NR2B subunit to become constitutively active, thereby inducing -amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor recruitment to the postsynaptic membrane and an increase in fEPSP. Coimmunoprecipitation demonstrated that Clz potentiates interactions among CaMKII, NR2B, and 5-HT1A-R, possibly in the membrane rafts of the postsynaptic density, because pretreatment with methyl–cyclodextrin, an agent that disrupts rafts, inhibited both coimmunoprecipitation as well as fEPSP. In Benzocaine hydrochloride summary, clozapine functions in the PFC by orchestrating a synergism among 5-HT1A-R, CaMKII, and NMDA-R, which augments Benzocaine hydrochloride excitability in the PFC neurons of layers II/III. Keywords:5-HT1Areceptor, Schizophrenia, Prefrontal cortex, Clozapine, Signal transduction == Introduction == Since its introduction in the 1950s, clozapine (Clz) has been one of the main antipsychotic agents used to treat schizophrenia (Roth 2003). Previously, another family of antipsychotics, exemplified by haloperidol, was utilized. These earlier pharmacological agents targeted the dopamine D1 and D2 receptors and ameliorated the positive symptoms of schizophrenia while introducing a spectrum of side effects termed extrapyramidal effects. Clz revolutionized the treatment strategy by attenuating the positive and negative symptoms of schizophrenia without extrapyramidal effects (Roth 2003). Unlike earlier antipsychotics, Clz displayed high affinity for Benzocaine hydrochloride multiple receptors, including serotonin 1A (5-HT1A-R), muscarinic, and dopamine D4 receptors. Due to these differences, the earlier antipsychotics were named typical while Clz and several of its analogues as atypical antipsychotics (Duncanet al.1999). Although there is still some debate on the brain regions that are involved, generally, the frontal lobe, temporal lobe and limbic system (specifically the cingulate gyrus, amygdala, hippocampus and thalamus) are implicated in schizophrenia. The current literature reports many interrelationships between limbic-cortical structures within the medial temporal lobe, frontal lobe, and cingulate gyrus (Shentonet al.2001). Thus, aberrations in Benzocaine hydrochloride any of these areas are likely to affect other functional brain regions and it is improbable that abnormalities in any single neural structure would adequately explain the spectrum of symptoms associated with schizophrenia. Rather, aberrations in the neuronal circuits within different brain regions may contribute to schizophrenic pathophysiology (Csernansky & Bardgett 1998). In corroboration, fMRI studies have revealed deficits in working memory performance associated with increased or decreased activation of the dorsolateral prefrontal cortex (PFC). Additionally, a dorsolateral PFC dysfunction in schizophrenic patients during a working memory task has been linked to the characteristic symptoms of disorganization observed in this disorder (Pauluset al.2003). Although the receptor-binding profiles of Clz have been examined, the signaling cascade by which it modulates brain activity is unclear. The general consensus is that antipsychotics modulate dopamine release in the described brain centers, thereby normalizing emotional levels (Banticket al.2001,Ichikawaet al.2001). Intriguingly, atypical antipsychotics such as Clz and olanzapine enhance dopamine release in the medial PFC of wild type but not 5-HT1A-R(/) mice (Diaz-Mataixet al.2005), which implicates the 5-HT1A-R in Clz-mediated neuronal activity. It is also known that the PFC glutamatergic (pyramidal) neurons innervate and regulate the dopamine-releasing activity of neurons in the ventral tegmental area (VTA) (Gao 2007). Therefore, clozapine-mediated regulation of the PFC pyramidal neurons would also have a direct effect on dopamine release in the VTA. Based on this reasoning, we have performed a mechanistic study of Clz-evoked electrical activity in the pyramidal neurons of the PFC. Our results show that Clz stimulates a novel pathway involving the 5-HT1A-R and CaMKII, in synergism with the NMDA-R, which triggers an increase in PFC electrical activity. We demonstrate that this 5-HT1A-R-mediated cascade bolsters interactions between CaMKII and the NR2B subunit of the NMDA-R. As shown in earlier studies, such CaMKII-NR2B interactions cause permanent activation of CaMKII and phosphorylation-mediated recruitment of the AMPA receptors (AMPA-R) to the post-synaptic terminals (Fink & Meyer 2002), which could account for the clozapine-evoked electrical activity in the PFC. == Materials and Methods == == Antibodies and Reagents == Rabbit anti-P-CaMKII, Rabbit polyclonal to Sin1 mouse anti-CaMKII, rabbit anti-NR2B, anti-5-HT1A-R (H-119), and Protein G agarose were obtained from Santa Cruz Biotechnology (Santa Cruz, CA). For protein estimation, a Protein Assay kit based on the Lowry Method was obtained from BioRad (Hercules, CA). WAY100635 (a 5-HT1A-R antagonist), Clz, 8-OH-DPAT (a.