Bacopa monnieri (Brahmi) improved novel object recognition task and increased cerebral vesicular glutamate transporter type 3 in sub-chronic phencyclidine rat model of schizophrenia.

Reduced vesicular glutamate transporter 1 (VGLUT1) and 2 (VGLUT2) indicate glutamatergic hypofunction leading to cognitive impairment in schizophrenia. However, VGLUT3 involvement in cognitive dysfunction has not been reported in schizophrenia. Brahmi (Bacopa monnieri) might be a new treatment and prevention for cognitive deficits in schizophrenia by acting on cerebral VGLUT3 density. We aimed to study cognitive enhancement- and neuroprotective-effects of Brahmi on novel object recognition and cerebral VGLUT3 immunodensity in sub-chronic (2 mg/kg, Bid, ip) phencyclidine (PCP) rat model of schizophrenia. Rats were assigned to three groups for cognitive enhancement effect study: Group 1, Control; Group 2, PCP administration; Group 3, PCP+Brahmi. A neuroprotective-effect study was also carried out. Rats were again assigned to three groups: Group 1, Control; Group 2, PCP administration; Group 3, Brahmi+PCP. Discrimination ratio (DR) representing cognitive ability was obtained from a novel object recognition task. VGLUT3 immunodensity was measured in the prefrontal cortex, striatum and cornu ammonis fields 1-3 (CA1-3) using immunohistochemistry. We found reduced DR in the PCP group, which occurred alongside VGLUT3 reduction in all brain areas. PCP+Brahmi showed higher DR score with increased VGLUT3 immunodensity in the prefrontal cortex and striatum. Brahmi+PCP group showed a higher DR score with increased VGLUT3 immunodensity in the prefrontal cortex, striatum and CA1-3. We concluded that reduced cerebral VGLUT3 was involved in cognitive deficit in PCP-administrated rats. Receiving Brahmi after PCP restored cognitive deficit by increasing VGLUT3 in the prefrontal cortex and striatum. Receiving Brahmi before PCP prevented cognitive impairment by elevating VGLUT3 in prefrontal cortex, striatum and CA1-3. Therefore, Brahmi could be a new frontier of restoration and prevention of cognitive deficit in schizophrenia.

Hippocampal Proteomic and Metabonomic Abnormalities in Neurotransmission, Oxidative Stress, and Apoptotic Pathways in a Chronic Phencyclidine Rat Model.

Schizophrenia is a neuropsychiatric disorder affecting 1% of the world's population. Due to both a broad range of symptoms and disease heterogeneity, current therapeutic approaches to treat schizophrenia fail to address all symptomatic manifestations of the disease. Therefore, disease models that reproduce core pathological features of schizophrenia are needed for the elucidation of pathological disease mechanisms. Here, we employ a comprehensive global label-free liquid chromatography-mass spectrometry proteomic (LC-MS(E)) and metabonomic (LC-MS) profiling analysis combined with the targeted proteomics (selected reaction monitoring and multiplex immunoassay) of serum and brain tissues to investigate a chronic phencyclidine (PCP) rat model in which glutamatergic hypofunction is induced through noncompetitive NMDAR-receptor antagonism. Using a multiplex immunoassay, we identified alterations in the levels of several cytokines (IL-5, IL-2, and IL-1ß) and fibroblast growth factor-2. Extensive proteomic and metabonomic brain tissue profiling revealed a more prominent effect of chronic PCP treatment on both the hippocampal proteome and metabonome compared to the effect on the frontal cortex. Bioinformatic pathway analysis confirmed prominent abnormalities in NMDA-receptor-associated pathways in both brain regions, as well as alterations in other neurotransmitter systems such as kainate, AMPA, and GABAergic signaling in the hippocampus and in proteins associated with neurodegeneration. We further identified abundance changes in the level of the superoxide dismutase enzyme (SODC) in both the frontal cortex and hippocampus, which indicates alterations in oxidative stress and substantiates the apoptotic pathway alterations. The present study could lead to an increased understanding of how perturbed glutamate receptor signaling affects other relevant biological pathways in schizophrenia and, therefore, support drug discovery efforts for the improved treatment of patients suffering from this debilitating psychiatric disorder.

Dietary Intake of Sulforaphane-Rich Broccoli Sprout Extracts during Juvenile and Adolescence Can Prevent Phencyclidine-Induced Cognitive Deficits at Adulthood.

Oxidative stress and inflammation play a role in cognitive impairment, which is a core symptom of schizophrenia. Furthermore, a hallmark of the pathophysiology of this disease is the dysfunction of cortical inhibitory γ-aminobutyric acid (GABA) neurons expressing parvalbumin (PV), which is also involved in cognitive impairment. Sulforaphane (SFN), an isothiocyanate derived from broccoli, is a potent activator of the transcription factor Nrf2, which plays a central role in the inducible expressions of many cytoprotective genes in response to oxidative stress. Keap1 is a cytoplasmic protein that is essential for the regulation of Nrf2 activity. Here, we found that pretreatment with SFN attenuated cognitive deficits, the increase in 8-oxo-dG-positive cells, and the decrease in PV-positive cells in the medial prefrontal cortex and hippocampus after repeated administration of phencyclidine (PCP). Furthermore, PCP-induced cognitive deficits were improved by the subsequent subchronic administration of SFN. Interestingly, the dietary intake of glucoraphanin (a glucosinolate precursor of SFN) during the juvenile and adolescence prevented the onset of PCP-induced cognitive deficits as well as the increase in 8-oxo-dG-positive cells and the decrease in PV-positive cells in the brain at adulthood. Moreover, the NRF2 gene and the KEAP1 gene had an epistatic effect on cognitive impairment (e.g., working memory and processing speed) in patients with schizophrenia. These findings suggest that SFN may have prophylactic and therapeutic effects on cognitive impairment in schizophrenia. Therefore, the dietary intake of SFN-rich broccoli sprouts during the juvenile and adolescence may prevent the onset of psychosis at adulthood.

Neuroprotective effects of Bacopa monnieri (Brahmi) on novel object recognition and NMDAR1 immunodensity in the prefrontal cortex, striatum and hippocampus of sub-chronic phencyclidine rat model of schizophrenia.

BACKGROUND: Cognitive impairment is a major problem, which eventually develops in schizophrenia. It contributes to the patients 'functional disability and cannot be attenuated by antipsychotic drugs. Bacopa monnieri (Brahmi), a neuroprotective herbal medicine in the elderly, might be a novel neuroprotective agent for prevention of cognitive deficit in schizophrenia. OBJECTIVE: To study neuroprotective effects ofBrahmi on novel object recognition task and cerebral glutamate/N-methyl-D- aspartate receptor subtype 1 (NMDAR1) immunodensity in sub-chronic phencyclidine (PCP) rat model ofschizophrenia. MATERIAL AND METHOD: Rats were assigned to three groups; Group-A: Control, Group-B: PCP administration and Group- C: Brahmi + PCP. Discrimination ratio (DR) representing cognitive ability was obtainedfrom novel object recognition task. NMDAR1 immunodensity was measured in prefrontal cortex, striatum, cornu ammonis fields I (CA 1) and 2/3 (CA2/3) and dentate gyrus (DG) using immunohistochemistry. RESULTS: DR was significantly reduced in PCP group compared with control. This occurred alongside NMDAR1 up-regulation in CA2/3 and DG but not in prefrontal cortex, striatum or CA1. Brahmi + PCP group showed an increased DR score up to normal which occurred alongside a significantly decreased NMDARI immunodensity in CA2/3 and DG compared with PCP group. CONCLUSION: Cognitive deficit observed in rats receiving PCP was mediated by NMDAR1 up-regulation in CA2/3 and DG Interestingly, receiving Brahmi before PCP administration can restore this cognitive deficit by decreasingNMDAR1 in these brain areas. Therefore, Brahmi could be a novel neuroprotective agentfor the prevention ofcognitive deficit in schizophrenia.

Repeated asenapine treatment produces a sensitization effect in two preclinical tests of antipsychotic activity.

Among several commonly used atypical antipsychotic drugs, olanzapine and risperidone cause a sensitization effect in the conditioned avoidance response (CAR) and phencyclidine (PCP)-induced hyperlocomotion paradigms--two well established animal tests of antipsychotic drugs, whereas clozapine causes a tolerance effect. Asenapine is a novel antipsychotic drug recently approved for the treatment of schizophrenia and manic disorders. It shares several receptor binding sites and behavioral features with other atypical antipsychotic drugs. However, it is not clear what type of repeated effect (sensitization or tolerance) asenapine would induce, and whether such an effect is transferrable to other atypicals. In this study, male adult Sprague-Dawley rats were first repeatedly tested with asenapine (0.05, 0.10 or 0.20 mg/kg, sc) for avoidance response or PCP (3.20 mg/kg, sc)-induced hyperlocomotion daily for 5 consecutive days. After 2-3 days of retraining/drug-free recovery, they were then challenged with asenapine (0.10 mg/kg, sc), followed by olanzapine (0.50 mg/kg, sc) and clozapine (2.50 mg/kg, sc). During the 5-day drug test period (the induction phase), repeated asenapine treatment progressively increased its inhibition of avoidance response and PCP-induced hyperlocomotion in a dose-dependent fashion. On the asenapine and olanzapine challenge tests (the expression phase), rats previously treated with asenapine still showed significantly lower avoidance response and lower PCP-induced hyperlocomotion than those previously treated with vehicle. An increased reactivity to clozapine challenge in prior asenapine-treated rats was also found in the PCP-induced hyperlocomotion test. These findings suggest that asenapine is capable of inducing a sensitization effect and a cross-sensitization to olanzapine and clozapine (to a lesser extent). Because the behavioral profile of asenapine in both tests is similar to that of olanzapine, but different from that of clozapine, we suggest that asenapine resembles olanzapine to a greater extent than clozapine in its therapeutic and side effect profiles.

Chronic cannabinoid exposure reduces phencyclidine-induced schizophrenia-like positive symptoms in adult rats.

RATIONALE: Chronic cannabis use can induce psychotic states that resemble schizophrenia. Yet, schizophrenic patients often smoke cannabis as a form of self-medication to counter the aversive symptoms of schizophrenia. We recently demonstrated an ameliorating effect of cannabinoid self-administration (SA) on negative and cognitive schizophrenia-like symptoms induced experimentally by the non-competitive N-methyl-D-aspartate receptor antagonist phencyclidine (PCP). Whether cannabinoid SA alleviates or exacerbates schizophrenia-like positive symptoms is still unclear. OBJECTIVES: This follow-up study aimed to evaluate the effect of self-administered cannabinoid on PCP-induced schizotypic positive symptoms in adult rats. METHODS: Male rats were trained to self-administer either the cannabinoid CB1 receptor agonist WIN 55,212-2 (WIN; 12.5 µg/kg/infusion) or its vehicle (Veh) intravenously. The effects of acute and chronic intermittent intraperitoneal administration of PCP (2.5 mg/kg) on motor parameters were then tested in Veh-SA and WIN-SA. RESULTS: Cannabinoid SA significantly attenuated the psychotomimetic effects of PCP exposure observed in control rats. Following acute PCP administration, WIN-SA animals displayed more frequent rearing and lower anxiety-like profile than Veh-SA rats. WIN-SA rats also exhibited lower behavioural sensitisation to chronic PCP treatment as demonstrated by reduced hyperlocomotion in response to an acute PCP challenge. In addition, parallel experiments performed in experimenter-administered rats that received WIN at comparable SA doses confirmed the ameliorating effects of cannabinoid exposure on PCP-induced schizotypic behaviours, indicating that motivational effects were not responsible for the ameliorative effects of cannabinoids. CONCLUSIONS: Our results indicate that cannabis may exert protective effects on positive schizotypic symptoms in adult animals such as hypermotility and anxiety state.

Time course of the attenuation effect of repeated antipsychotic treatment on prepulse inhibition disruption induced by repeated phencyclidine treatment.

Antagonism of prepulse inhibition (PPI) deficits produced by psychotomimetic drugs has been widely used as an effective tool for the study of the mechanisms of antipsychotic action and identifying potential antipsychotic drugs. Many studies have relied on the acute effect of a single administration of antipsychotics, whereas patients with schizophrenia are treated chronically with antipsychotic drugs. The clinical relevance of acute antipsychotic effect in this model is still an open question. In this study, we investigated the time course of repeated antipsychotic treatment on persistent PPI deficit induced by repeated phencyclidine (PCP) treatment. After a baseline test with saline, male Sprague-Dawley rats were repeatedly injected with either vehicle, haloperidol (0.05mg/kg), clozapine (5.0 or 10.0mg/kg), olanzapine (2.0mg/kg), risperidone (1.0mg/kg) or quetiapine (10mg/kg), followed by PCP (1.5mg/kg, sc) and tested for PPI once daily for 6 consecutive days. A single injection of PCP disrupted PPI and this effect was maintained with repeated PCP injections throughout the testing period. Acute clozapine, but not other antipsychotic drugs, attenuated acute PCP-induced PPI disruption at both tested doses. With repeated treatment, clozapine and quetiapine maintained their attenuation, while risperidone enhanced its effect with a significant reduction of PCP-induced disruption toward the end of treatment period. In contrast, repeated haloperidol and olanzapine treatments were ineffective. The PPI effects of these drugs were more conspicuous at a higher prepulse level (e.g. 82dB) and were dissociable from their effects on startle response and general activity. Overall, the repeated PCP-PPI model appears to be a useful model for the study of the time-dependent antipsychotic effect, and may help identify potential treatments that have a quicker onset of action than current antipsychotics.

T-817MA, a novel neurotrophic compound, ameliorates phencyclidine-induced disruption of sensorimotor gating.

RATIONALE: Neurodegenerative changes have been suggested to provide a basis for the pathophysiology of schizophrenia. T-817MA (1-{3-[2-(1-benzothiophen-5-yl) ethoxy] propyl} azetidin-3-ol maleate) is a novel compound with neuroprotective and neurite-outgrowth effects, as elicited in rat primary cultured neurons. OBJECTIVES: We examined the effect of T-817MA on phencyclidine (PCP)-induced disruption of prepulse inhibition (PPI), a measure of sensorimotor gating, in male Wistar rats. MATERIALS AND METHODS: In chronic experiments, male Wistar rats were injected intermittently with PCP (2.0 mg/kg, i.p., three times per week) or vehicle (saline, 2.0 ml/kg) for 1 month. T-817MA (0.21 or 0.07 mg/ml, p.o.) or distilled water was administered throughout the study period. In an acute experiment, T-817MA (8.4 mg/kg, p.o.) or distilled water was administered, followed by treatment with PCP (2.0 mg/kg, i.p.) or vehicle (saline, 2.0 ml/kg), before PPI measurements. RESULTS: Intermittent administration of PCP for 1 month induced persistent disruption of PPI. Coadministration of T-817MA at 0.21 mg/ml but not 0.07 mg/ml completely blocked PCP-induced disruption of PPI, whereas T-817MA (0.21 mg/ml) by itself did not show a significant effect on PPI in control rats. On the other hand, single administration of T-817MA did not affect PPI disruption by acute treatment with PCP. CONCLUSIONS: These results suggest that T-817MA is effective in ameliorating sensorimotor gating deficits caused by chronic PCP treatment, possibly via neuroprotective actions. Our findings provide a novel therapeutic approach for patients with schizophrenia.

Moderate body hypothermia alleviates behavioral and EEG manifestations of audiogenic seizures in metaphit-treated rats.

We investigated the effects of hypothermia on the incidence and EEG signs of audiogenic seizures in rats treated with metaphit (1-[1(3isothiocyanatophenyl)-cyclohexyl] piperidine), an experimental model of generalized reflex epilepsy. After i.p. injection with metaphit (10 mg/kg) Wistar rats were exposed to audiogenic stimulation at hourly intervals during the time course of the experiment. After intermittent use of an ice pack 8 h after the metaphit treatment, when seizure was fully developed, the body temperature was reduced to 30 +/- 0.5 degrees C in one half of the rats, and maintained at 37 +/- 0.5 degrees C in the other half. Saline-injected rats served as a control group. In the hypothermia group, the incidence of audiogenic seizures induced by metaphit was completely suppressed during the 3 consecutive testing times, while no signs of epileptiform activity were noted in EEG tracings. The termination of hypothermic treatment resulted in the recovery of seizure susceptibility, and during audiogenic stimulation, bursts of spiking activity were recorded in the EEGs of metaphit-treated rats. These findings indicate that moderate body hypothermia is an effective anticonvulsant treatment for audiogenic seizures in metaphit-treated rats.

Long-term effects of developmental PCP administration on sensorimotor gating in male and female rats.

RATIONALE: Acutely administered N-methyl-D-asparate (NMDA) antagonists are used to model schizophrenia, as measured by impairments in sensorimotor gating reflected in decreases in prepulse inhibition of the startle response (PPI). Aspects of acute NMDA receptor antagonism limit the applications of these models. OBJECTIVE: The aim of this paper is to determine the long-term effects of developmental phencyclidine (PCP) treatment on sensorimotor gating in both male and female rats. MATERIALS AND METHODS: Male and female Sprague Dawley rats were injected with PCP (10 mg/kg s.c.) on postnatal days (PN) 7, 9, and 11 and were tested for PPI on PN 32-34. The groups were then divided and some of the animals received a single dose of PCP (10 mg/kg s.c.) on PN 45. The animals were tested again for PPI at approximately 1, 4, and 6 weeks after the treatment. RESULTS: There were no significant effects of neonatal-only treatment. One week after the PN 45 treatment, animals that were treated as neonates and as adolescents (PCP/PCP) were significantly impaired in PPI in both sexes. Male and female PCP/PCP rats also had significant increases in acoustic startle response 4 weeks posttreatment, which subsequently declined. PPI impairments in both sexes recovered over time and the adolescent-only treated females showed significant increases (improvement) in PPI approximately 6 weeks posttreatment. CONCLUSION: These data suggest that treatment with an NMDA receptor antagonist during adolescence or early adulthood can produce a relatively long-term impairment of PPI (approximately 1 week) and that this effect is more pronounced in male animals.

The effects of delta sleep-inducing peptide on incidence and severity in metaphit-induced epilepsy in rats.

The effects of delta sleep-inducing peptide (DSIP) on metaphit- (1-(1(3-isothiocyanatophenyl)-cyclohexyl) (piperidine)-) induced audiogenic seizures in adult male Wistar rats were studied. The animals were divided into four experimental groups: 1. saline injected; 2. metaphit administered (10 mg x kg (-1)); 3. metaphit administered plus DSIP injected (dose range 0.1-1 mg x kg (-1)) and 4. DSIP injected (1 mg x kg (-1)). Upon treatment, the rats were exposed to sound stimulation ( 100 +/- 3 dB, 60 s) at hourly intervals and the incidence and severity (running, clonus and tonus) of seizures were analyzed. In most animals, metaphit led to EEG abnormalities and elicited epileptiform activity recorded as spikes, polyspikes and spike-wave complex and increased power spectra. Time-course studies revealed the peak of convulsive activity 7-12 h after the injection in metaphit-treated rats. DSIP acted as an anticonvulsant and the most potent anticonvulsive dose of 1 mg x kg (-1)significantly increased power spectra of deltawaves (2-11 h) in comparison with the saline-control group and decreased the incidence and duration of convulsive response, as well as mean seizure grade of metaphit-induced convulsions. These results suggest that DSIP should be considered as having potential anticonvulsant activity in this animal model.

APH, an N-methyl-D-aspartate receptor antagonist, blocks the metaphit-induced audiogenic seizures in rats.

The effect of the competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, (+/-)2-amino-7-phosphonoheptanoic acid (APH) on electrocorticographic (ECoG) activity and behavior was studied in the model of epilepsy induced by systemic application of metaphit (1-(1-(3-isothiocyanatophenyl)-cyclohexyl)-piperidine). Male Wistar rats were injected with metaphit intraperitoneally (10 mg/kg, i.p.), and exposed to intense audio stimulation (electric bell generating 100 +/- 3 dB at animal level for 60 s) 1 h after administration and at 1-h intervals thereafter. ECoG tracings showed appearance of paroxysmal activity in form of spikes, spike-wave complexes and ECoG seizures. Audiogenic seizures consisted of wild running followed by clonic and tonic convulsions. Each behavioral seizure response had a characteristic ECoG correlate. The incidence and severity of seizures increased with time, reaching a peak 8-12 h after metaphit administration, and then gradually decreased until 31 h, when no animal responded to sound stimulation. APH was injected intracerebroventricularly (0.005, 0.01, 0.02, 0.03 and 0.05 mumol icv in 5 microL of sterile saline) after the 8th hour of audiogenic testing (AGS). APH inhibited seizures in a dose-dependent manner. The minimum dose which blocked seizures in all animals was 0.03 mumol. However, ECoG signs of seizure susceptibility were not suppressed by APH. After varying periods of time, behavioral seizures reappeared. It seems that APH blocks epileptiform propagation, but has less influence on the epileptogenic activity caused by metaphit.

Factors in the lethality of i.v. phencyclidine in conscious dogs.

1. Pretreatment were pancuronium prevented convulsions and hyperthermia, but had no effect on acidemia or changes in cardiovascular parameters after intravenous (i.v.) infusion of phencyclidine (PCP). 2. While dogs survived higher amounts of PCP, they failed to regain spontaneous respiratory function. 3. Mechanical ventilation alone increased the mean lethal dose/time of PCP and reduced the effects of PCP on arterial systolic pressure, cardiac output, and PCO2. 4. EKG showed ventricular arrhythmias, which progressed to death. 5. Phenytoin pretreatment plus respiratory assistance increased the lethal dose and reduced PCP effects on cardiovascular parameters, body temperature, and cardiac rhythm. 6. Blocking of convulsions prevented hyperthermia and acidemia; respiratory support reduced circulatory effects, but respired dogs then died, at higher doses, from a primary myocardial toxicity of PCP.

In vitro and in vivo evaluation of cis-methyl-phencyclidine (CIS-MPCP) as a potential antagonist of phencyclidine (PCP).

In four preparations/tests (isolated nerve, ventricular strip, rotarod, and mouse acute lethality), cis-N-phenyl-4-methyl-cyclohexyl piperidine (cis-MPCP) was consistently less active than PCP and trans-MPCP. As expected, cis-MPCP, at 10(-4)M, which did not depress the action potential evoked on frog sciatic nerves, reduced by half both the nerve block and prolongation of relative refractory period caused by PCP. However, cis-MPCP at 10(-6)M, which by itself had little effect, failed to reduce the positive inotropic effect of PCP on the field-stimulated rat ventricular strip. Cis-MPCP also failed to decrease the ataxic effect of 6 mg/kg PCP (ED80) in the mouse rotarod test. Finally, at a dose that was neither ataxic nor lethal to mice (20 mg/kg), cis-MPCP failed to reduce the 24-hour LD50 of PCP. These data suggest that the actions of PCP are mediated through a multiple receptor system.

Teratogenic potential of phencyclidine in the mouse.

Pregnant CD-1 mice were given phencyclidine by gavage on days 6-15 of gestation, at dose levels of 60, 80, 100, and 120 mg/kg/day. The mice were killed on day 18 and the offspring were examined for external, visceral, and skeletal alterations. There was a significant increase in the average percent of malformed fetuses per litter only at the 120 mg/kg/day dose level (6.1% versus 1.2% for the control), a dose level which resulted in the death of 8 of 18 dams before scheduled sacrifice. At dose levels less than 120 mg/kg/day, the incidence of malformations was not significantly higher than the control value, in spite of the presence of overt maternal toxicity. Because a significant number of malformations was not seen at dose levels which were not highly toxic to the dams, it was concluded that phencyclidine was not demonstrated to be a teratogen in the mouse.