Sung Woo Park

Decreased Serum Brain-Derived Neurotrophic Factor Levels in Elderly Korean with Dementia

Objective The primary purpose of this study was to investigate the differences in the serum brain-derived neurotrophic factor (BDNF) level between elderly Korean people over 65 years with and without dementia. Methods 171 individuals over 65 years were enrolled in this study. Screening for cognitive impairments was carried out using the Mini-Mental Status Examination-Korean version (MMSE-KC). One hundred thirty-two subjects scored below 1.5 standard deviations (SD) of the mean MMSE-KC score, and these were evaluated using the Consortium to Establish a Registry for Alzheimers Disease, Korean version (CERAD-K) and the Geriatric Depression Scale (GDS). The Clinical Dementia Rating Scale (CDRS) and the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) diagnostic criteria were used for further evaluation. Subjects with a CDRS score of 1 or higher were classified as having Alzheimers disease (AD), and subjects with a CDRS score of 0.5 were classified as having a mild cognitive impairment (MCI). Subjects with a CDRS score of 0 were classified as having aging-associated cognitive decline (AACD). Serum BDNF levels were analyzed using the enzyme-linked immunosorbent assay (ELISA) method. Results The serum BDNF levels were significantly lower in the subjects with MCI and AD compared with the healthy controls (p<0.01). A significant correlation was found between the total MMSE-KC score and serum BDNF level (r=0.295; p<0.01). However, no significant correlation was observed between the severity of MMSE-KC and the total GDS score. A significant difference was found in the total score of GDS between the AACD group and subjects with AD (p<0.05). Conclusion This study suggested that BDNF might be involved in the pathophysiology of cognitive decline in elderly people.

Effect of treadmill exercise on the BDNF-mediated pathway in the hippocampus of stressed rats.

A growing body of evidence suggests that exercise enhances hippocampal plasticity and function through BDNF up-regulation, which is potentiated by antidepressant treatment. However, little is known about the molecular mechanisms mediating the effect of exercise. The present study investigated the effect of treadmill exercise on PI3K/Akt signaling, which mediates synaptic plasticity in the hippocampus of stressed rats. Rats were subjected to immobilization stress 2h/day for 7 days. The rats were run on the treadmill at a speed of 15m/min, 30min/day, for 5 days. Western blotting was used to assess changes in the levels of phospho-tyr(490)-Trk receptor, phospho-ser(473)-Akt, phospho-ser(9)-GSK-3β, phospho-ser(2448)- mTOR, and phosphor-thr(389)-p70S6K, and in BDNF and various synaptic proteins. Immobilization stress significantly decreased BDNF expression and phosphorylation of Trk receptor, Akt, GSK-3β, mTOR, and p70S6K in the hippocampus of rats; furthermore, synaptophysin, PSD-95, neuroligin 1, and β-neurexin were decreased. Treadmill exercise significantly attenuated the decreased expression of these proteins. Moreover, exercise significantly increased PI3K/Akt signaling in the absence of immobilization stress. These results suggest that treadmill exercise reverses stress-induced changes in the rat hippocampus via an increase in PI3K/Akt signaling and may induce a functional reconnection of hippocampal synapses that mediate antidepressant actions.

Effects of antipsychotic drugs on BDNF, GSK-3β, and β-catenin expression in rats subjected to immobilization stress.

Brain-derived neurotrophic factor (BDNF), glycogen synthase kinase-3β (GSK-3β), and β-catenin have been reported to be altered in patients with schizophrenia and have been targeted by antipsychotic drugs. Atypical antipsychotics, but not typical antipsychotics, exert neuroprotective effects by regulating these proteins. In this study, we analyzed the effects of the atypical antipsychotic drugs olanzapine and aripiprazole and a typical antipsychotic drug, haloperidol, on the expression of BDNF, phosphorylated GSK-3β, and β-catenin in the hippocampus of rats subjected to immobilization stress. Rats were subjected to immobilization stress 6h/day for 3 weeks. The effects of olanzapine (2 mg/kg), aripiprazole (1.5 mg/kg), and haloperidol (1.0 mg/kg) were determined on BDNF, serine⁹-phosphorylated GSK-3β, and β-catenin expression by Western blotting. Immobilization stress significantly decreased the expression of BDNF, phosphorylated GSK-3β, and β-catenin in the hippocampus. Chronic administration of olanzapine and aripiprazole significantly attenuated the decreased expression of these proteins in the hippocampus of rats caused by immobilization stress, and significantly increased the levels of these proteins even without the immobilization stress. However, chronic haloperidol had no such effect. These results suggest that olanzapine and aripiprazole may exert beneficial effects by upregulating BDNF, phosphorylated GSK-3β, and β-catenin in patients with schizophrenia.

Differential effects of aripiprazole and haloperidol on BDNF-mediated signal changes in SH-SY5Y cells ☆

Recent studies have suggested that first and second generation antipsychotics (FGAs and SGAs) have different neuroprotective effects. However, the molecular mechanisms of SGAs are not fully understood, and investigations into changes in intracellular signaling related to their neuroprotective effects remain scarce. In the present study, we compared the SGA aripiprazole with the FGA haloperidol in SH-SY5Y human neuroblastoma cells via brain-derived neurotrophic factor (BDNF)-mediated signaling, notably BDNF, glycogen synthase kinase-3beta (GSK-3beta), and B cell lymphoma protein-2 (Bcl-2). We examined the effects of aripiprazole (five and 10 microM) and haloperidol (one and 10 microM) on BDNF gene promoter activity in SH-SY5Y cells transfected with a rat BDNF promoter fragment (-108 to +340) linked to the luciferase reporter gene. The changes in BDNF, p-GSK-3beta, and Bcl-2 levels were measured by Western blot analysis. The haloperidol was not associated with a significant difference in BDNF promoter activity. In contrast, aripiprazole was associated with increased BDNF promoter activity only with a dose of 10 microM (93%, p<0.01). Treatment with aripiprazole at 10 microM increased the levels of BDNF by 85%, compared with control levels (p<0.01), whereas haloperidol had no effect. Moreover, cells treated with aripirazole effectively increased the levels of GSK-3beta phosphorylation and Bcl-2 at doses of five and 10 microM (30% and 58% and 31% and 80%, respectively, p<0.05 or p<0.01). However, haloperidol had no effects on p-GSK-3 beta and Bcl-2 expression. This study showed that aripiprazole, but not haloperidol, appeared to offer neuroprotective effects on human neuronal cells. The actions of signaling systems associated with BDNF may represent key targets for both aripiprazole and haloperidol, but the latter may be associated with distinct effects. These differences might be related to the different therapeutic effects of FGAs and SGAs in patients with schizophrenia.

Differential effects of antidepressant drugs on mTOR signalling in rat hippocampal neurons

Recent studies suggest that ketamine produces antidepressant actions via stimulation of mammalian target of rapamycin (mTOR), leading to increased levels of synaptic proteins in the prefrontal cortex. Thus, mTOR activation may be related to antidepressant action. However, the mTOR signalling underlying antidepressant drug action has not been well investigated. The aim of the present study was to determine whether alterations in mTOR signalling were observed following treatment with antidepressant drugs, using ketamine as a positive control. Using Western blotting, we measured changes in the mTOR-mediated proteins and synaptic proteins in rat hippocampal cultures. Dendritic outgrowth was determined by neurite assay. Our findings demonstrated that escitalopram, paroxetine and tranylcypromine significantly increased levels of phospho-mTOR and its down-stream regulators (phospho-4E-BP-1 and phospho-p70S6K); fluoxetine, sertraline and imipramine had no effect. All drugs tested increased up-stream regulators (phospho-Akt and phospho-ERK) levels. Increased phospho-mTOR induced by escitalopram, paroxetine or tranylcypromine was significantly blocked in the presence of specific PI3K, MEK or mTOR inhibitors, respectively. All drugs tested also increased hippocampal dendritic outgrowth and synaptic proteins levels. The mTOR inhibitor, rapamycin, significantly blocked these effects on escitalopram, paroxetine and tranylcypromine whereas fluoxetine, sertraline and imipramine effects were not affected. The effects of escitalopram, paroxetine and tranylcypromine paralleled those of ketamine. This study presents novel in vitro evidence indicating that some antidepressant drugs promote dendritic outgrowth and increase synaptic protein levels through mTOR signalling; however, other antidepressant drugs seem to act via a different pathway. mTOR signalling may be a promising target for the development of new antidepressant drugs.

Protective effects of atypical antipsychotic drugs against MPP+-induced oxidative stress in PC12 cells

Recent studies have suggested that some atypical antipsychotic drugs may have protective properties against oxidative stress. To confirm these findings, we investigated the protective effects of atypical antipsychotic drugs such as olanzapine, aripiprazole, and ziprasidone on oxidative stress induced by the N-methyl-4-phenylpyridinium (MPP(+)) ion in PC12 cells. Haloperidol, a typical antipsychotic drug, was used for comparison. We determined the antioxidant effects of atypical antipsychotic drugs using a number of measures, including cell viability, the formation of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and Bax levels. MPP(+) treatment induced significant loss of cell viability, the formation of ROS, reduction of SOD activity, and up-regulation of Bax expression. However, olanzapine, aripiprazole and ziprasidone reversed these effects caused by MPP(+) treatment, but ziprasidone did not influence cell viability. In contrast, haloperidol did not affect all these effects. Moreover, haloperidol strongly increased the expression of Bax under MPP(+)-free conditions. Olanzapine, aripiprazole, and ziprasidone, but not haloperidol, may exert antioxidant effects through modulating ROS levels, SOD activity, and Bax expression to provide protective effects against MPP(+)-induced oxidative stress in PC12 cells. These results suggest that some atypical antipsychotic drugs have a useful therapeutic effect by reducing oxidative stress in schizophrenic patients.

Differential effects of ziprasidone and haloperidol on immobilization stress-induced mRNA BDNF expression in the hippocampus and neocortex of rats

Recent in vivo and in vitro experiments have demonstrated that second-generation antipsychotic drugs (SGAs) might have neuroprotective effects. Ziprasidone is a SGA that is efficacious in the treatment of schizophrenia. In this study, we sought to analyze the effects of ziprasidone on the expression of the neuroprotective protein brain-derived neurotrophic factor (BDNF) in the rat hippocampus and neocortex, with or without immobilization stress. The effect of ziprasidone (2.5mg/kg) on the expression of BDNF mRNA was determined by in situ hybridization in tissue sections from the rat hippocampus and neocortex. Haloperidol (1.0mg/kg) was used for comparison. Haloperidol strongly decreased the expression of BDNF mRNA in both the hippocampal and cortical regions, with or without immobilization stress (p<0.01). In contrast, the administration of ziprasidone significantly attenuated the immobilization stress-induced decrease in BDNF mRNA expression in the rat hippocampus and neocortex (p<0.01). Ziprasidone exhibited differential effects on BDNF mRNA expression in the rat hippocampus and neocortex. These results suggest that ziprasidone might have a neuroprotective effect by recovering stress-induced decreases in BDNF mRNA expression.

Effects of olanzapine on brain-derived neurotrophic factor gene promoter activity in SH-SY5Y neuroblastoma cells.

PURPOSE Atypical antipsychotics have neuroprotective effects, which may be one of the mechanisms for their success in the treatment of schizophrenia. Growing evidence suggest that brain-derived neurotrophic factor (BDNF) is abnormally regulated in patients with schizophrenia, and its expression can be up-regulated by atypical antipsychotics. Atypical antipsychotic drugs may positively regulate transcription of the BDNF gene, but the molecular mechanism of atypical antipsychotic drug action on BDNF gene activity has not been investigated. The aim of the present study was to explore the possible involvement of some intracellular signaling pathways in olanzapine action on BDNF promoter activity. METHODS We examined the effects of olanzapine on BDNF gene promoter activity in SH-SY5Y cells transfected with a rat BDNF promoter fragment (-108 to +340) linked to the luciferase reporter gene. The changes in glycogen synthase kinase-3beta (GSK-3beta) and cAMP response element (CRE) binding protein (CREB) phosphorylation were measured by Western blot analysis. RESULTS Olanzapine treatment (10-100 microM) increased basal BDNF gene promoter activity in a dose-dependent manner and increased protein levels at high dose, and inhibitors of protein kinase A (PKA), H-89 (10 microM), phosphatidylinositol 3-kinase (PI3K), wortmannin (0.01 microM), PKC (protein kinase C), GF109203 (10 microM), calcium/calmodulin kinase II (CaMKII), and KN-93 (20 microM) partially attenuated the stimulatory effect of olanzapine on BDNF promoter activity. In line with these results, a Western blot study showed that olanzapine (100 microM) increased phosphorylated levels of GSK-3beta and CREB, which are notable downstream effectors of the PKA, PI3K, PKC, and CaMKII signaling pathways. CONCLUSIONS These results demonstrate that the up-regulation of olanzapine on BDNF gene transcription is linked with enhancement of CREB-mediated transcription via PKA, PI3K, PKC, and CaMKII signaling pathways, and olanzapine may exert neuroprotective effects through these signaling pathways in neuronal cells.

Genetic association of BDNF val66met and GSK-3β-50T/C polymorphisms with tardive dyskinesia

Aims:  Neurodegenerative processes may be involved in the pathogenesis of tardive dyskinesia (TD), and a growing body of evidence suggests that brain‐derived neurotrophic factor (BDNF) plays a role in both the antipsychotic effects and the pathogenesis of TD. BDNF and glycogen synthase kinase (GSK)‐3β are important in neuronal survival, and thus abnormal regulation of BDNF and GSK‐3β may contribute to TD pathophysiology. This study investigated the relationship between two polymorphisms, val66met in the BDNF coding region and ‐50T/C in the GSK‐3β promoter, and susceptibility to TD among a matched sample of patients having schizophrenia with TD (n = 83), patients with schizophrenia without TD (n = 78), and normal control subjects (n = 93).

Effects of antipsychotic drugs on the expression of synaptic proteins and dendritic outgrowth in hippocampal neuronal cultures

Recent evidence has suggested that atypical antipsychotic drugs regulate synaptic plasticity. We investigated whether some atypical antipsychotic drugs (olanzapine, aripiprazole, quetiapine, and ziprasidone) altered the expression of synapse‐associated proteins in rat hippocampal neuronal cultures under toxic conditions induced by B27 deprivation. A typical antipsychotic, haloperidol, was used for comparison. We measured changes in the expression of various synaptic proteins including postsynaptic density protein‐95 (PSD‐95), brain‐derived neurotrophic factor (BDNF), and synaptophysin (SYP). Then we examined whether these drugs affected the dendritic morphology of hippocampal neurons. We found that olanzapine, aripiprazole, and quetiapine, but not haloperidol, significantly hindered the B27 deprivation‐induced decrease in the levels of these synaptic proteins. Ziprasidone did not affect PSD‐95 or BDNF levels, but significantly increased the levels of SYP under B27 deprivation conditions. Moreover, olanzapine and aripiprazole individually significantly increased the levels of PSD‐95 and BDNF, respectively, even under normal conditions, whereas haloperidol decreased the levels of PSD‐95. These drugs increased the total outgrowth of hippocampal dendrites via PI3K signaling, whereas haloperidol had no effect in this regard. Together, these results suggest that the up‐regulation of synaptic proteins and dendritic outgrowth may represent key effects of some atypical antipsychotic drugs but that haloperidol may be associated with distinct actions. Synapse 67:224–234, 2013.