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PloS One 2015The Auditory Steady-State Response (ASSR) in the electroencephalogram (EEG) is usually reduced in schizophrenia (SZ), particularly to 40 Hz stimulation. The gamma...
The Auditory Steady-State Response (ASSR) in the electroencephalogram (EEG) is usually reduced in schizophrenia (SZ), particularly to 40 Hz stimulation. The gamma frequency ASSR deficit has been attributed to N-methyl-D-aspartate receptor (NMDAR) hypofunction. We tested whether the NMDAR antagonist, phencyclidine (PCP), produced similar ASSR deficits in rats. EEG was recorded from awake rats via intracranial electrodes overlaying the auditory cortex and at the vertex of the skull. ASSRs to click trains were recorded at 10, 20, 30, 40, 50, and 55 Hz and measured by ASSR Mean Power (MP) and Phase Locking Factor (PLF). In Experiment 1, the effect of different subcutaneous doses of PCP (1.0, 2.5 and 4.0 mg/kg) on the ASSR in 12 rats was assessed. In Experiment 2, ASSRs were compared in PCP treated rats and control rats at baseline, after acute injection (5 mg/kg), following two weeks of subchronic, continuous administration (5 mg/kg/day), and one week after drug cessation. Acute administration of PCP increased PLF and MP at frequencies of stimulation below 50 Hz, and decreased responses at higher frequencies at the auditory cortex site. Acute administration had a less pronounced effect at the vertex site, with a reduction of either PLF or MP observed at frequencies above 20 Hz. Acute effects increased in magnitude with higher doses of PCP. Consistent effects were not observed after subchronic PCP administration. These data indicate that acute administration of PCP, a NMDAR antagonist, produces an increase in ASSR synchrony and power at low frequencies of stimulation and a reduction of high frequency (> 40 Hz) ASSR activity in rats. Subchronic, continuous administration of PCP, on the other hand, has little impact on ASSRs. Thus, while ASSRs are highly sensitive to NMDAR antagonists, their translational utility as a cross-species biomarker for NMDAR hypofunction in SZ and other disorders may be dependent on dose and schedule.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Biomarkers; Brain; Computer Simulation; Electrodes; Electroencephalography; Enzyme Inhibitors; Evoked Potentials, Auditory; Male; Phencyclidine; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Schizophrenia
PubMed: 26258486
DOI: 10.1371/journal.pone.0134979 -
The Journal of Biological Chemistry Aug 2016Human Cys-loop receptors are important therapeutic targets. High-resolution structures are essential for rational drug design, but only a few are available due to...
Human Cys-loop receptors are important therapeutic targets. High-resolution structures are essential for rational drug design, but only a few are available due to difficulties in obtaining sufficient quantities of protein suitable for structural studies. Although expression of proteins in E. coli offers advantages of high yield, low cost, and fast turnover, this approach has not been thoroughly explored for full-length human Cys-loop receptors because of the conventional wisdom that E. coli lacks the specific chaperones and post-translational modifications potentially required for expression of human Cys-loop receptors. Here we report the successful production of full-length wild type human α7nAChR from E. coli Chemically induced chaperones promote high expression levels of well-folded proteins. The choice of detergents, lipids, and ligands during purification determines the final protein quality. The purified α7nAChR not only forms pentamers as imaged by negative-stain electron microscopy, but also retains pharmacological characteristics of native α7nAChR, including binding to bungarotoxin and positive allosteric modulators specific to α7nAChR. Moreover, the purified α7nAChR injected into Xenopus oocytes can be activated by acetylcholine, choline, and nicotine, inhibited by the channel blockers QX-222 and phencyclidine, and potentiated by the α7nAChR specific modulators PNU-120596 and TQS. The successful generation of functional human α7nAChR from E. coli opens a new avenue for producing mammalian Cys-loop receptors to facilitate structure-based rational drug design.
Topics: Animals; Bungarotoxins; Escherichia coli; Escherichia coli Proteins; Humans; Isoxazoles; Lidocaine; Molecular Chaperones; Phencyclidine; Phenylurea Compounds; Recombinant Proteins; Xenopus; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 27385587
DOI: 10.1074/jbc.M116.729970 -
PloS One 2014Schizophrenia and similar psychoses induced by NMDA-type glutamate receptor antagonists, such as phencyclidine (PCP) and ketamine, usually develop after adolescence....
Schizophrenia and similar psychoses induced by NMDA-type glutamate receptor antagonists, such as phencyclidine (PCP) and ketamine, usually develop after adolescence. Moreover, adult-type behavioral disturbance following NMDA receptor antagonist application in rodents is observed after a critical period at around 3 postnatal weeks. These observations suggest that the schizophrenic symptoms caused by and psychotomimetic effects of NMDA antagonists require the maturation of certain brain neuron circuits and molecular networks, which differentially respond to NMDA receptor antagonists across adolescence and the critical period. From this viewpoint, we have identified a novel developmentally regulated phencyclidine-responsive transcript from the rat thalamus, designated as prt6, as a candidate molecule involved in the above schizophrenia-related systems using a DNA microarray technique. The transcript is a non-coding RNA that includes sequences of at least two microRNAs, miR132 and miR212, and is expressed strongly in the brain and testis, with trace or non-detectable levels in the spleen, heart, liver, kidney, lung and skeletal muscle, as revealed by Northern blot analysis. The systemic administration of PCP (7.5 mg/kg, subcutaneously (s.c.)) significantly elevated the expression of prt6 mRNA in the thalamus at postnatal days (PD) 32 and 50, but not at PD 8, 13, 20, or 24 as compared to saline-treated controls. At PD 50, another NMDA receptor antagonist, dizocilpine (0.5 mg/kg, s.c.), and a schizophrenomimetic dopamine agonist, methamphetamine (4.8 mg/kg, s.c.), mimicked a significant increase in the levels of thalamic prt6 mRNAs, while a D2 dopmamine receptor antagonist, haloperidol, partly inhibited the increasing influence of PCP on thalamic prt6 expression without its own effects. These data indicate that prt6 may be involved in the pathophysiology of the onset of drug-induced schizophrenia-like symptoms and schizophrenia through the possible dysregulation of target genes of the long non-coding RNA or microRNAs in the transcript.
Topics: Animals; Antipsychotic Agents; Base Sequence; Blotting, Northern; Cloning, Molecular; Dopamine Agonists; Dopamine Antagonists; Gene Expression Profiling; Gene Expression Regulation, Developmental; Hallucinogens; Male; Molecular Sequence Data; Oligonucleotide Array Sequence Analysis; Organ Specificity; Phencyclidine; RNA, Messenger; RNA, Untranslated; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Thalamus; Time Factors
PubMed: 24886782
DOI: 10.1371/journal.pone.0097955 -
Journal of Neurochemistry Feb 2013Decreased parvalbumin expression is a hallmark of the pathophysiology of schizophrenia and has been associated with abnormal cognitive processing and decreased network...
Decreased parvalbumin expression is a hallmark of the pathophysiology of schizophrenia and has been associated with abnormal cognitive processing and decreased network specificity. It is not known whether this decrease is due to reduced expression of the parvalbumin protein or degeneration of parvalbumin-positive interneurons (PV(+) interneurons). In this study, we examined PV(+) expression in two rat models of cognitive dysfunction in schizophrenia: the environmental social isolation (SI) and pharmacological neonatal phencyclidine (neoPCP) models. Using a stereological method, the optical fractionator, we counted neurons, PV(+) interneurons, and glial cells in the medial prefrontal cortex (mPFC) and hippocampus (HPC). In addition, we quantified the mRNA level of parvalbumin in the mPFC. There was a statistically significant reduction in the number of PV(+) interneurons (p = 0.021) and glial cells (p = 0.024) in the mPFC of neonatal phencyclidine rats, but not in SI rats. We observed no alterations in the total number of neurons, hippocampal PV(+) interneurons, parvalbumin mRNA expression or volume of the mPFC or HPC in the two models. Thus, as the total number of neurons remains unchanged following phencyclidine (PCP) treatment, we suggest that the decreased number of counted PV(+) interneurons represents a reduced parvalbumin protein expression below immunohistochemical detection limit rather than a true cell loss. Furthermore, these results indicate that the effect of neonatal PCP treatment is not limited to neuronal populations.
Topics: Age Factors; Animals; Animals, Newborn; Autoradiography; Brain; Cell Count; Cognition Disorders; Disease Models, Animal; Excitatory Amino Acid Antagonists; Gene Expression Regulation, Developmental; Male; Motor Activity; Neuroglia; Neurons; Parvalbumins; Phencyclidine; Phosphopyruvate Hydratase; RNA, Messenger; Rats; Schizophrenia; Social Isolation
PubMed: 23083323
DOI: 10.1111/jnc.12061 -
The Western Journal of Medicine Nov 1975Phencyclidine is now one of the most frequently used main ingredients of "street drug" preparations. Its effects are highly dose dependent and three varieties of acute...
Phencyclidine is now one of the most frequently used main ingredients of "street drug" preparations. Its effects are highly dose dependent and three varieties of acute intoxication have been seen clinically associated with different dosages and routes of administration. Most persons using phencyclidine smoke it sprinkled on parsley in low doses. The presence of horizontal and vertical nystagmus associated with hypertension in a patient who is agitated or comatose are diagnostic of a phencyclidine intoxicated state. Sensory isolation and intravenous administration of diazepam in the event of seizure activity have proved effective in the treatment of acute intoxicated states. Phencyclidine has pronounced behavioral toxicity and several deaths due to this agent have now been documented. It is unknown whether seizure activity or respiratory depression is the primary cause of death in pharmacological overdoses.
Topics: Diagnosis, Differential; Humans; Phencyclidine; Psychoses, Substance-Induced; Substance-Related Disorders
PubMed: 1210329
DOI: No ID Found -
Biological & Pharmaceutical Bulletin Sep 2009We investigated the involvement of glutamic acid in neural development by injecting phencyclidine (PCP) into neonatal ICR mice. Neonatal mice were injected with PCP at... (Comparative Study)
Comparative Study
We investigated the involvement of glutamic acid in neural development by injecting phencyclidine (PCP) into neonatal ICR mice. Neonatal mice were injected with PCP at 10 mg/kg or saline on postnatal days 7, 9 and 11, and their behavioral, anatomical and neurochemical changes were analyzed in adulthood. PCP-treated mice exhibited an increase in PCP-induced hyperactivity and impairments of spatial working memory and social interaction behavior. The impairment of social interaction behavior was significantly reversed by administration of clozapine, D-cycloserine, flumazenil, or SHC50911, a gamma-aminobutyrate B (GABA(B)) receptor antagonist. A decrease in the number of parvalbumin-positive cells and spine density in the frontal cortex, nucleus accumbens and hippocampus were evident in the brains of PCP-treated mice. Measurement of brain monoamine and their metabolite contents in adulthood indicated brain area-dependent and neurotransmitter-specific changes in monoamine metabolism. These findings suggest that neonatal treatment with PCP in mice leads to enhanced sensitivity to PCP and impairment of spatial working memory and social interaction behaviors in adulthood, which may be associated with reduced spine density and GABAergic interneurons and changes in monoamine metabolism. Furthermore, pharmacologic experiments suggest the potential applicability of neonatally PCP-treated mice as a useful animal model for new antipsychotic drug screening.
Topics: Aging; Animals; Animals, Newborn; Behavior, Animal; Biogenic Monoamines; Brain; Brain Chemistry; Interpersonal Relations; Male; Memory; Mice; Mice, Inbred ICR; Motor Activity; Phencyclidine; Schizophrenia
PubMed: 19721235
DOI: 10.1248/bpb.32.1576 -
Translational Psychiatry Feb 2015Increasing evidence points to a role for dysfunctional glutamate N-methyl-D-aspartate receptor (NMDAR) neurotransmission in schizophrenia. D-aspartate is an atypical...
Increasing evidence points to a role for dysfunctional glutamate N-methyl-D-aspartate receptor (NMDAR) neurotransmission in schizophrenia. D-aspartate is an atypical amino acid that activates NMDARs through binding to the glutamate site on GluN2 subunits. D-aspartate is present in high amounts in the embryonic brain of mammals and rapidly decreases after birth, due to the activity of the enzyme D-aspartate oxidase (DDO). The agonistic activity exerted by D-aspartate on NMDARs and its neurodevelopmental occurrence make this D-amino acid a potential mediator for some of the NMDAR-related alterations observed in schizophrenia. Consistently, substantial reductions of D-aspartate and NMDA were recently observed in the postmortem prefrontal cortex of schizophrenic patients. Here we show that DDO mRNA expression is increased in prefrontal samples of schizophrenic patients, thus suggesting a plausible molecular event responsible for the D-aspartate imbalance previously described. To investigate whether altered D-aspartate levels can modulate schizophrenia-relevant circuits and behaviors, we also measured the psychotomimetic effects produced by the NMDAR antagonist, phencyclidine, in Ddo knockout mice (Ddo(-)(/-)), an animal model characterized by tonically increased D-aspartate levels since perinatal life. We show that Ddo(-/-) mice display a significant reduction in motor hyperactivity and prepulse inhibition deficit induced by phencyclidine, compared with controls. Furthermore, we reveal that increased levels of D-aspartate in Ddo(-/-) animals can significantly inhibit functional circuits activated by phencyclidine, and affect the development of cortico-hippocampal connectivity networks potentially involved in schizophrenia. Collectively, the present results suggest that altered D-aspartate levels can influence neurodevelopmental brain processes relevant to schizophrenia.
Topics: Adult; Animals; Behavior, Animal; Brain; Case-Control Studies; D-Aspartate Oxidase; DNA Methylation; Disease Models, Animal; Excitatory Amino Acid Antagonists; Female; Functional Neuroimaging; Humans; Magnetic Resonance Imaging; Male; Mice; Mice, Knockout; Middle Aged; Motor Activity; Phencyclidine; Prefrontal Cortex; Prepulse Inhibition; Schizophrenia
PubMed: 25689573
DOI: 10.1038/tp.2015.2 -
Current Neuropharmacology 20173-Methoxyphencyclidine (3-MeO-PCP) and 3-methoxyrolicyclidine (3-MeOPCPy) are two new psychoactive substances (NPS). The aims of the present study were the elucidation...
New Psychoactive Substances 3-Methoxyphencyclidine (3-MeO-PCP) and 3-Methoxyrolicyclidine (3-MeO-PCPy): Metabolic Fate Elucidated with Rat Urine and Human Liver Preparations and their Detectability in Urine by GC-MS, "LC-(High Resolution)-MSn" and "LC-(High Resolution)-MS/MS".
BACKGROUND
3-Methoxyphencyclidine (3-MeO-PCP) and 3-methoxyrolicyclidine (3-MeOPCPy) are two new psychoactive substances (NPS). The aims of the present study were the elucidation of their metabolic fate in rat and pooled human liver microsomes (pHLM), the identification of the cytochrome P450 (CYP) isoenzymes involved, and the detectability using standard urine screening approaches (SUSA) after intake of common users' doses using gas chromatography-mass spectrometry (GC-MS), liquid chromatography-multi-stage mass spectrometry (LC-MSn), and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS).
METHODS
For metabolism studies, rat urine samples were treated by solid phase extraction or simple precipitation with or without previous enzymatic conjugate cleavage. After analyses via LC-HR-MSn, the phase I and II metabolites were identified.
RESULTS
Both drugs showed multiple aliphatic hydroxylations at the cyclohexyl ring and the heterocyclic ring, single aromatic hydroxylation, carboxylation after ring opening, O-demethylation, and glucuronidation. The transferability from rat to human was investigated by pHLM incubations, where Odemethylation and hydroxylation were observed. The involvement of the individual CYP enzymes in the initial metabolic steps was investigated after single CYP incubations. For 3-MeO-PCP, CYP 2B6 was responsible for aliphatic hydroxylations and CYP 2C19 and CYP 2D6 for O-demethylation. For 3-MeO-PCPy, aliphatic hydroxylation was again catalyzed by CYP 2B6 and O-demethylation by CYP 2C9 and CYP 2D6 Conclusions: As only polymorphically expressed enzymes were involved, pharmacogenomic variations might occur, but clinical data are needed to confirm the relevance. The detectability studies showed that the authors' SUSAs were suitable for monitoring the intake of both drugs using the identified metabolites.
Topics: Animals; Chromatography, Liquid; Cytochrome P-450 Enzyme System; Female; Gas Chromatography-Mass Spectrometry; Humans; Liver; Male; Metabolic Networks and Pathways; Microsomes, Liver; Phencyclidine; Psychotropic Drugs; Rats; Rats, Wistar; Time Factors; Urine
PubMed: 27758707
DOI: 10.2174/1570159X14666161018151716 -
The International Journal of... Oct 2006N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine (PCP) and ketamine can evoke psychotic symptoms in normal individuals and schizophrenic patients.... (Comparative Study)
Comparative Study
N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine (PCP) and ketamine can evoke psychotic symptoms in normal individuals and schizophrenic patients. Here, we have examined the effects of PCP (5 mg/kg) and ketamine (25 mg/kg) on the efflux of serotonin (5-HT) in the medial prefrontal cortex (mPFC) and their possible blockade by the antipsychotics, clozapine, olanzapine and haloperidol, as well as ritanserin (5-HT2A/2C receptor antagonist) and prazosin (alpha1-adrenoceptor antagonist). The systemic administration, but not the local perfusion, of the two NMDA receptor antagonists markedly increased the efflux of 5-HT in the mPFC. The atypical antipsychotics clozapine (1 mg/kg) and olanzapine (1 mg/kg), and prazosin (0.3 mg/kg), but not the classical antipsychotic haloperidol (1 mg/kg), reversed the PCP- and ketamine-induced increase in 5-HT efflux. Ritanserin (5 mg/kg) was able to reverse only the effect of PCP. These findings indicate that an increased serotonergic transmission in the mPFC is a functional consequence of NMDA receptor hypofunction and this effect is blocked by atypical antipsychotic drugs.
Topics: Analysis of Variance; Animals; Antipsychotic Agents; Benzodiazepines; Brain Chemistry; Clozapine; Dose-Response Relationship, Drug; Drug Interactions; Excitatory Amino Acid Antagonists; Haloperidol; Ketamine; Male; Microdialysis; Olanzapine; Phencyclidine; Prefrontal Cortex; Rats; Rats, Wistar; Serotonin; Time Factors
PubMed: 16316487
DOI: 10.1017/S1461145705005900 -
The International Journal of... Jul 2012Administration of phencyclidine (PCP) is acknowledged to generate a model of psychosis in animals. With the identification of genetic susceptibility factors for...
Administration of phencyclidine (PCP) is acknowledged to generate a model of psychosis in animals. With the identification of genetic susceptibility factors for schizophrenia and bipolar disorder, great efforts have been made to generate genetic animal models for major mental illnesses. As these disorders are multifactorial, comparisons among drug-induced (non-genetic) and genetic models are becoming an important issue in biological psychiatry. A major barrier is that the standard mouse strain used in the generation of genetic models is C57BL/6, whereas almost all studies with PCP-induced models have utilized other strains. To fill this technical gap, we systematically compared the behavioural changes upon PCP administration in different mouse strains, including C57BL/6N, C57BL/6J, ddY, and ICR. We observed strain differences in PCP-induced hyperlocomotion and enhanced immobility in the forced swim test (ddY>>C57BL/6N and 6J>ICR). In contrast, there was no strain difference in the impairment of recognition memory in the novel object recognition memory test after withdrawal of chronic PCP administration. This study provides practical guidance for comparing genetic with PCP-induced models of psychosis in C57BL/6. Furthermore, such strain differences may provide a clue to the biological mechanisms underlying PCP-induced endophenotypes possibly relevant to major mental illnesses.
Topics: Analysis of Variance; Animals; Animals, Outbred Strains; Behavior, Animal; Dose-Response Relationship, Drug; Exploratory Behavior; Frontal Lobe; Hallucinogens; Hyperkinesis; Male; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Motor Activity; Phencyclidine; Species Specificity; Swimming; Time Factors
PubMed: 21733237
DOI: 10.1017/S146114571100085X