Chronic Treatment of Fluoxetine Increases Expression of NCAM140 in the Rat Hippocampus

OBJECTIVES: Most of the mechanisms reported for antidepressant drugs are the enhancement of neurite outgrowth and neuronal survival in the rat hippocampus. Neural cell adhesion molecule 140(NCAM140) has been implicated as having a role in cell-cell adhesion, neurite outgrowth, and synaptic plasticity. In this report, we have performed to elucidate a correlation among chronic antidepressant treatments, NCAM140 expression, and activation of phosphorylated cyclicAMP responsive element binding protein(pCREB) which is a downstream molecule of NCAM140-mediated intracellular signaling pathway in the rat hippocampus. METHODS: Fluoxetine(10mg/kg) was injected acutely(daily injection for 5days) or chronically(daily injection for 14days) in adult rats. RNA and protein were extracted from the rat hippocampus, respectively. Real-time RTPCR was performed to analyze the expression pattern of NCAM140 gene and western blot analyses for the activation of the phosphorylation ratio of CREB. RESULTS: Chronic fluoxetine treatments increased NCAM140 expression 1.3 times higher than control in rat hippocampus. pCREB immunoreactivity in the rat hippocampus with chronic fluoxetine treatment was increased 4.0 times higher than that of control. CONCLUSION: Chronic fluoxetine treatment increased NCAM140 expression and pCREB activity in the rat hippo-campus. Our data suggest that NCAM140 and pCREB may play a role in the clinical efficacy of antidepressants promoting the neurite outgrowth and neuronal survival.

Fluoxetine-induced Changes on Activity of Tryptophan Hydroxylase at RBL-2H3 Cells / 대한정신약물학회지

OBJECTIVES: The aim of the present study is to explore the effect of fluoxetine on transcription, translation and activity of tryptophan hydroxylase (TPH), and intracellular level of serotonin. METHODS: The expression level of the TPH mRNA and the protein, the TPH enzyme activity, and the intracellular level of serotonin were explored at the fluoxetine-treated RBL-2H3 cells. Real-time RT-PCR and immunoblotting analysis confirmed changes in the expression of TPH mRNA and protein. The activity of TPH was measured using [3H]tryptophan. The intracellular level of serotonin was measured by HPLC. RESULTS: The TPH activity was gradually increased on time from 24hr to 72hr. The real-time RT-PCR also revealed that the TPH mRNA was increased at 12, 24 and 72hr in the fluoxetine-treated RBL-2H3 cells. The immunoblotting analysis also revealed that the TPH protein was decreased at 72hr in the fluoxetine-treated RBL-2H3 cells. The intracellular level of serotonin was increased at 48hr after treatment of fluoxetine. CONCLUSION: Fluoxetine induced the increases of the TPH mRNA, the TPH enzyme activity and intracellular level of serotonin, and the decrease of the TPH protein expression at the RBL- 2H3 cells.

Characterization of Differentially Expressed Genes upon Chronic Fluoxetine Treatment in Rat C6 Glioma Cells / 대한정신약물학회지

OBJECTIVE: The aim of this study was to identify diffrentially regulated genes after the treatment of fluoxetine in rat C6 glioma cells using cDNA microarray chip techniques and real-time RT-PCR. METHODS: Cells were incubated for 24 hours, and for 72 hours with or without 10 uM fluoxetine. Total RNAs extracted from cells were reversely transcribed to cDNA. These cDNA were used to carry out cDNA microarray chip. A part of the up-/down-regulated genes in cDNA microarray result were confirmed by real-time RT-PCR. RESULTS: 1) Genes in fluoxetinetreated cells for 72 hours (chronic treatment) were more regulated than that in fluoxetine-treated cells for 24 hours (acute treatment). 2) The expression level of Gs gene in fluoxetine-treated cells for 24 hours hardly altered, but that of Gs in fluoxetine-treated cells for 72 hours significantly increased. The expression of Gi2 also decreased in 72 hours in relation to 24 hours after the administration of fluoxetine. 3) The expression level of NCAM140 gene in fluoxetine-treated cells was higher than that in control cells. CONCLUSION: We identified genes (Gs, Gi2 and NCAM140) related to neural plasticity and intracellular signal transduction cascade from our result. This implies that fluoxetine may inhibit atrophy or death of impaired neural cells by promoting neurite outgrowth.

Screening of Differentially Expressed Genes between PC12 Cells and A123.7 Cells

The cAMP-dependent protein kinase(PKA) is an intracellular enzyme with serine-threonine kinase activity that plays a key role in cell growth, differentiation, and apoptosis in eukaryotes. In order to understand the PKA signal transduction pathway regulating cell life cycle and identify its role, we focused on the characterization of up-/down-regulated genes by PKA using the differential display polymerase chain reaction. Seven differentially expressed sequence tags(DEST) have been obtained. Among these DESTs, 2DESTs were homologous to the sequence of genes from BLAST search result. KC1-5 DEST that was up-regulated in A123.7 cells was highly corresponded to mouse apoptosis-related gene(MA-3) or mouse mRNA for topoisomerase inhibitor suppressed(TIS). MA-3 was induced in various types of apoptosis, specially in NGF-deprived apoptotic PC12 cells, TIS was down-regulated in the RVC lymphoma cells incubated with topoisomerase inhibitor that induces DNA strand breakages. PG1-1DEST that was highly expressed in PC12 cells was corresponded to transposon Tn103'-end. Tnansposon Tn10 was up-regulated in differentiated myeloblastic ML-1 cells by 12-O-tetradecanoylphorbol-13-acetate. This study illuminates that MA-3/TIS was down-regulated by PKA activity, and transposon Tn10 was up-regulated by it.