Chronic phencyclidine induces inflammatory responses and activates GSK3ß in mice.

Use of phencyclidine (PCP) in rodents can mimic some aspects of schizophrenia. However, the underlying mechanism is still unclear. Growing evidence indicates that neuroinflammation plays a significant role in the pathophysiology of schizophrenia. In this study, we focused on inflammatory responses as target of PCP for inducing schizophrenia-like symptoms. 3-month-old C57BL/6J mice received daily injections of PCP (20 mg/kg, i.p.) or saline for one week. PCP-injected mice produced schizophrenia-like behaviours including impaired spatial short-term memory assessed by the Y-maze task and sensorimotor gating deficits in a prepulse inhibition task. Simultaneously, chronic PCP administration induced astrocyte and microglial activation in both the cortex and hippocampus. Additionally, the proinflammatory cytokine interleukin-1ß was significantly up-regulated in PCP administrated mice. Furthermore, PCP treatment decreased ratio of the phospho-Ser9 epitope of glycogen synthase kinase-3ß (GSK3ß) over total GSK3ß, which is indicative of increased GSK3ß activity. These data demonstrate that chronic PCP in mouse produces inflammatory responses and GSK3ß activation.

Therapeutic effects of quetiapine on memory deficit and brain ß-amyloid plaque pathology in a transgenic mouse model of Alzheimer's disease.

Our previous study has shown the preventive effects of quetiapine, an atypical antipsychotic drug, on memory impairment and brain pathological changes in a mouse model of Alzheimer's disease (AD). The aim of the present study was to evaluate the therapeutic effects of quetiapine on memory deficit and neuropathology in an amyloid precursor protein (APP)/presenilin-1 (PS1) double transgenic mouse model of AD. The APP/PS1 mice started to have detectable brain ß-amyloid (Aß) at 3 months of age. Non-transgenic and transgenic mice were treated with quetiapine (0, 2.5, or 5 mg/(kg day)) in drinking water from the age of 4 months. After 8 months of continuous quetiapine administration, memory deficit was reversed and brain Aß plaque pathology was attenuated in the AD mice. Quetiapine also decreased the soluble Aß peptide levels in brain and cerebrospinal fluid (CSF), and attenuated the decreased synaptic protein levels in the AD mice. Furthermore, quetiapine normalized the abnormal activity of glycogen synthase kinase-3ß (GSK-3ß), an AD-involved kinase, in the AD mice. These results suggest that quetiapine can treat and alleviate the neuropathology in an APP/PS1 transgenic mouse model of AD, and indicate that quetiapine may have therapeutic effects in the treatment of AD.

Quetiapine modulates conditioned anxiety and alternation behavior in Alzheimer's transgenic mice.

Quetiapine, an atypical antipsychotic drug, is effective in treating the behavioral and psychological symptoms in Alzheimer's disease (AD). However, it is presently unclear whether quetiapine has beneficial effects on memory and whether the effects of quetiapine on psychological symptoms are associated with its effect on memory in AD. The present study was designed to examine the effect of chronic administration of quetiapine on the conditioned (generalized) anxiety that is related to learning experience of open arm exposure in the elevated T-maze (ETM) test in an amyloid precursor protein (APP)/presenilin 1 (PS1) double transgenic mouse model of AD. In a 2nd experiment, the effect of quetiapine on memory per se was investigated in a Y-maze test in AD mice. Non-transgenic and transgenic mice were treated with quetiapine in drinking water from the age of 2 months. After continuous treatment with quetiapine (5 mg/kg/day) for 10 months, mice were tested for conditioned anxiety on the ETM task. After ETM testing, the expression of brain-derived neurotrophic factor (BDNF), a neuroprotective protein, was examined by immunohistochemistry in the basolateral amygdala (BLA) and hippocampus. In the 2nd experiment, the effect of quetiapine (2.5 or 5 mg/kg/day) on the short-term memory in AD mice was tested in a Y-maze test. After 10 months of administration, quetiapine prevented the decrease of conditioned anxiety and cerebral BDNF in AD mice. In addition, quetiapine also prevented memory impairment in the Y-maze test in AD mice. These findings suggest that the therapeutic mechanism of quetiapine on anxiety in AD may be associated with its beneficial effect on memory and its neuroprotective effect on cerebral BDNF expression.

Antipsychotics promote the differentiation of oligodendrocyte progenitor cells by regulating oligodendrocyte lineage transcription factors 1 and 2.

AIMS: Oligodendrocyte/myelin abnormalities may be an important component of the pathogenesis found in schizophrenia. The aim of this current study was to examine the possible effects of the antipsychotic drugs (APDs) haloperidol (HAL), olanzapine (OLA), and quetiapine (QUE) on the development of oligodendroglial lineage cells. MAIN METHODS: CG4 cells, an oligodendrocyte progenitor cell line, were treated with various concentrations of HAL, OLA, or QUE for specific periods. The proliferation and differentiation of the CG4 cells were measured. The regulation of CG4 cell differentiation by oligodendrocyte lineage transcription factors 1 and 2 (Olig1 and Olig2) was examined. KEY FINDINGS: The APDs used in this study had no effect on the proliferation of CG4 cells. The APDs elevated the expression of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), a specific marker of oligodendrocytes, and promoted the CG4 cells to differentiate into CNP positive oligodendrocytes. QUE and OLA increased the expression of both Olig1 and Olig2 whereas HAL only increased the expression of Olig2. SIGNIFICANCE: Our findings suggest that oligodendrocyte development is a target of HAL, OLA, and QUE and provide further evidence of the important role of oligodendrocytes in the pathophysiology and treatment of schizophrenia. They also indicate that the expression level of oligodendrocyte/myelin-related genes could be profoundly affected by APDs, which should be considered in future studies aiming to measure the oligodendrocyte/myelin-related gene expressions in schizophrenia patients.

Sensorimotor gating and memory deficits in an APP/PS1 double transgenic mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with cognitive deterioration and neuropsychiatric symptoms. Sensorimotor gating deficit has been identified in neuropsychiatric diseases. The aim of the present study was to evaluate the possible sensorimotor gating deficit and its correlation to memory impairment and cerebral ß-amyloid (Aß) plaque deposits in an amyloid precursor protein (APP)/presenilin-1 (PS1) double transgenic mouse model of AD. The sensorimotor gating in 3-, 7- and-22-month-old non-transgenic and transgenic mice was evaluated in a prepulse inhibition (PPI) task. Results revealed that the PPI was lower in the 7- and 22-month-old transgenic mice compared with the age-matched control, while the response to startle pulse-alone in the transgenic and non-transgenic mice was comparable. Congo red staining showed that Aß neuropathology of transgenic mice aggravated with age, and the 3-month-old transgenic mice started to have minimum brain Aß plaques, corresponding to the early stage of AD phenotype. Furthermore, memory impairment in the 7-month-old transgenic mice was detected in a water maze test. These results suggest that the sensorimotor gating is impaired with the progressing of AD phenotype, and its deficit may be correlated to cerebral Aß neuropathology and memory impairment in the APP/PS1 transgenic mouse model of AD.

Myelination deficit in a phencyclidine-induced neurodevelopmental model of schizophrenia.

Increasing evidence supports an important role of oligodendrocytes and myelination in the pathogenesis of schizophrenia. Oligodendrocytes are the myelin-producing cells in the central nervous system. To test the myelination dysfunction hypothesis of schizophrenia, possible myelination dysfunction was evaluated in a phencyclidine (PCP)-induced neurodevelopmental model of schizophrenia. On postnatal day (PND) 2, rat pups were treated with a total 14 subcutaneous daily injections of PCP (10mg/kg) or saline. PCP-injected rats showed schizophrenia-like behaviors including hyper-locomotor activity on PND 30 and prepulse inhibition deficit on PND 31. Cerebral myelination was measured by the expression of myelin basic protein (MBP), and cerebral mature oligodendrocytes were measured by the expression of glutathione S-transferase (GST)-π in rats. The results indicate that the expressions of MBP on PND 16, 22 and 32 and GST-π on PND 22 decreased in the frontal cortex of PCP-injected rats. Our results suggest that there was myelination impairment in the phencyclidine-induced schizophrenia animal model, and indicate that myelination may play an important role in the pathogenesis of schizophrenia.