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

Abstract

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.