Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidermal growth factor (EGF) comprises a structurally related family of proteins containing heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor alpha (TGFalpha) that regulates the development of dopaminergic neurons as well as monoamine metabolism. We assessed the contribution of EGF to schizophrenia by measuring EGF family protein levels in postmortem brains and in fresh serum of schizophrenic patients and control subjects. EGF protein levels were decreased in the prefrontal cortex and striatum of schizophrenic patients, whereas the levels of HB-EGF and TGFalpha were not significantly different in any of the regions examined. Conversely, EGF receptor expression was elevated in the prefrontal cortex. Serum EGF levels were markedly reduced in schizophrenic patients, even in young, drug-free patients. Chronic treatment of animals with the antipsychotic drug haloperidol had no influence on EGF levels in the brain or serum. These findings suggest that there is abnormal EGF production in various central and peripheral tissues of patients with both acute and chronic schizophrenia. EGF might thus provide a molecular substrate for the pathologic manifestation of the illness, although additional studies are required to determine a potential link between impaired EGF signaling and the pathology/etiology of schizophrenia.
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PMID:Abnormal expression of epidermal growth factor and its receptor in the forebrain and serum of schizophrenic patients. 1219 10

Abnormality in cytokine signaling is implicated in the neuropathology of schizophrenia. Previously, we established an animal model for schizophrenia by administering epidermal growth factor (EGF) to neonatal rats. Here we investigated effects of the anthraquinone derivatives emodin (3-methyl-1,6,8-trihydroxyanthraquinone) and sennoside (bis-[D: -glucopyranosyl-oxy]-tetrahydro-4,4'-dihydroxy-dioxo[bianthracene]-2,2'-dicarboxylic acid) on behaviors of this model and EGF signaling. Subchronic oral administration of emodin (50 mg/kg) suppressed acoustic startle responses and abolished prepulse inhibition (PPI) deficits in this rodent model. ANCOVA revealed that emodin had distinct effects on PPI and startle responses. In contrast, sennoside (50 mg/kg) had no effects. Emodin attenuated weight gain initially during treatment but had no apparent effect on weight gain and locomotor activity thereafter. Application of emodin to neocortical cultures attenuated the phosphorylation of ErbB1 and ErbB2. We conclude that emodin can both attenuate EGF receptor signaling and ameliorate behavioral deficits. Therefore, emodin might be a novel class of a pro-drug for anti-psychotic medication.
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PMID:The anthraquinone derivative Emodin ameliorates neurobehavioral deficits of a rodent model for schizophrenia. 1830 53

The atypical antipsychotic drug clozapine is effective in treatment-refractory schizophrenia. The intracellular signaling pathways that mediate clozapine action remain unknown. A potential candidate is the mitogen-activated protein kinase extracellular signal-regulated kinase (MAPK-ERK) cascade that links G-protein-coupled receptor and ErbB growth factor signaling systems, thereby regulating synaptic plasticity and connectivity, processes impaired in schizophrenia. Here, we examined how clozapine differentially modulated phosphorylation of the MAPK isoforms, ERK1/ERK2 in primary murine prefrontal cortical neurons compared to the typical antipsychotic drug haloperidol. While clozapine and haloperidol acutely decreased cortical pERK1 activation, only clozapine but not haloperidol stimulated pERK1 and pERK2 with continued drug exposure. This delayed ERK increase however, did not occur via the canonical dopamine D(2)-Gi/o-PKA or serotonin 5HT(2A)-Gq-phospholipase-C-linked signaling pathways. Rather, epidermal growth factor (EGF) receptor signaling mediated clozapine-induced ERK activation, given dose-dependent reduction of pERK1 and pERK2 stimulation with the EGF receptor inhibitor, AG1478. Immunocytochemical studies indicated that clozapine treatment increased EGF receptor (Tyr1068) phosphorylation. In vivo mouse treatment studies supported the in vitro findings with initial blockade, subsequent activation, and normalization of the cortical ERK response over 24 h. Furthermore, in vivo clozapine-induced ERK activation was significantly reduced by AG1478. This is the first report that clozapine action on prefrontal cortical neurons involves the EGF signaling system. Since EGF receptor signaling has not been previously linked to antipsychotic drug action, our findings may implicate the EGF system as a molecular substrate in treatment-resistant schizophrenia.
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PMID:Clozapine-induced ERK1 and ERK2 signaling in prefrontal cortex is mediated by the EGF receptor. 1927 91

Recently, neurotrophic factors and cytokines have been shown to be associated in psychiatric disorders, such as schizophrenia, bipolar disorder, and depression. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the EGF family, serves as a neurotrophic molecular and plays a significant role in the brain. We generated mice in which HB-EGF activity is disrupted specifically in the ventral forebrain. These knockout mice showed (a) behavioral abnormalities similar to those described in psychiatric disorders, which were ameliorated by typical or atypical antipsychotics, (b) altered dopamine and serotonin levels in the brain, (c) decreases in spine density in neurons of the prefrontal cortex, (d) reductions in the protein levels of the NR1 subunit of the N-methyl-D-aspartate (NMDA) receptor and post-synaptic protein-95 (PSD-95), (e) decreases in the EGF receptor, and in the calcium/calmodulin-dependent protein kinase II (CaMK II) signal cascade. These results suggest the alterations affecting HB-EGF signaling could comprise a contributing factor in psychiatric disorder.
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PMID:Generation and characterization of conditional heparin-binding EGF-like growth factor knockout mice. 1982 4

Treatment resistance remains a major obstacle in schizophrenia, with antipsychotic drugs (APDs) being ineffective in about one third of cases. Poor response to standard therapy leaves the APD clozapine as the only effective treatment for many patients. The reason for the superior efficacy of clozapine is unknown, but as we have proposed previously it may involve modulation of neuroplasticity and connectivity through induction of interconnected mitogenic signalling pathways. These include the mitogen-activated protein kinase-extracellular signal regulated kinase (MAPK-ERK) cascade and epidermal growth factor (EGF)/ErbB systems. Clozapine, distinct from other APDs, induced initial inhibition and subsequent activation of the ERK response in prefrontal cortical (PFC) neurons in vitro and in vivo, an action mediated by the EGF receptor (ErbB1). Here we examine additionally the striatum of C57Bl/6 mice to determine if clozapine, olanzapine, and haloperidol differentially regulate the ERK1/2 pathway in a region or time-specific manner conditional on the EGF receptor. Following acute treatment, only clozapine caused delayed striatal ERK phosphorylation through EGF receptor phosphorylation (tyrosine 1068 site) and MEK that paralleled cortical ERK phosphorylation. Olanzapine induced initial pERK1-specific blockade and an elevation 24-h later in PFC but had no effect in the striatum. By contrast, haloperidol significantly stimulated pERK1 in striatum for up to 8 h, but exerted limited effect in PFC. Clozapine but not olanzapine or haloperidol recruited the EGF receptor to signal to ERK. These in-vivo data reinforce our previous findings that clozapine's action may be uniquely linked to the EGF signalling system, potentially contributing to its distinctive clinical profile.
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PMID:Clozapine induction of ERK1/2 cell signalling via the EGF receptor in mouse prefrontal cortex and striatum is distinct from other antipsychotic drugs. 2194 60

Treatment of the positive psychotic symptoms of schizophrenia with standard antipsychotic drugs (APDs) is ineffective in a proportion of cases. For these treatment resistant patients the alternative is the APD clozapine which is superior to other agents but carries serious side effects. Why clozapine is uniquely effective is unknown, but we have previously postulated may involve G-protein coupled receptor (GPCR) and epidermal growth factor (EGF) receptor (ErbB1) transactivation signaling to the mitogen-activated protein kinase-extracellular signal regulated kinase (MAPK-ERK) cascade. This was based upon clozapine induced initial down-regulation and delayed ErbB1 mediated activation of the cortical and striatal ERK response in vivo distinct from other APDs. This study investigated if modulation of the ErbB1-ERK1/2 pathway by clozapine, olanzapine and haloperidol affected expression of the ERK substrates p90RSK and c-Fos, factors that regulate transcription of proteins associated with neuroplasticity and synapse formation in C57Bl/6 mice. In cortex and striatum, acute clozapine treatment induced biphasic p90RSK phosphorylation via MEK that paralleled ERK phosphorylation independent of EGF receptor blockade. By contrast, olanzapine and haloperidol caused p90RSK phosphorylation that was not concomitant with ERK signaling over a 24-hour period. For c-Fos, clozapine elevated expression 24h after administration, a timeframe consistent with ERK activation at 8h. Alternatively, haloperidol stimulation of c-Fos levels limited to the striatum was in accord with direct transcriptional regulation through ERK. The unique spatio-temporal expression of downstream nuclear markers of the ErbB1-ERK pathway invoked by clozapine may contribute to its effectiveness in treatment resistant schizophrenia.
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PMID:Clozapine regulation of p90RSK and c-Fos signaling via the ErbB1-ERK pathway is distinct from olanzapine and haloperidol in mouse cortex and striatum. 2314 70

Receptor transactivation or crosstalk are terms referring to instances in which the signaling of a given receptor is regulated by a different class of receptor. The epidermal growth factor (EGF) and the dopaminergic systems in the brain are closely related to schizophrenia with respect to both etiology and treatment. Thus, we investigated the functional interactions between the EGF receptor (EGFR), which belongs to the receptor tyrosine kinase family, and the dopamine D2-like receptors (D2R, D3R, and D4R), which are members of the G protein-coupled receptor (GPCR) family. Among D2-like receptors, the signaling of D3R was selectively inhibited by EGFR stimulation. Moreover loss-of-function assays showed that tyrosine-phosphorylated GRK2 mediates this inhibition by acting on the second intracellular loop of D3R. Considering that both EGFR and D3R are closely related to schizophrenia, this study could provide new molecular insight into the etiology of the disorder.
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PMID:The EGF receptor inhibits the signaling of dopamine D3 receptor through the phosphorylation of GRK2 on tyrosine residues. 2857 29