Long-term Treatment with Olanzapine Increases the Number of Sox2 and Doublecortin Expressing Cells in the Adult Subventricular Zone

BACKGROUND & OBJECTIVE: Continuously active neurogenic regions in the adult brain are located in the subventricular zone (SVZ) of the lateral ventricles and subgranular zone of the hippocampal dentate gyrus. Neurogenesis is modulated by many factors such as growth factors, neurotransmitters and hormones. Neuropsychiatric drugs, especially antidepressants, mood stabilizers and antipsychotics may also affect the origin of neuronal cells. METHOD: The purpose of this study was to determine the effects of chronic olanzapine treatment on adult rat neurogenesis at the level of the SVZ. The number of neuroblasts was evaluated using immunohistochemical and fluorescent detection of sex determining region Y-box 2 and doublecortin expressing cells. RESULTS & CONCLUSION: The results indicate that olanzapine has proneurogenic effects on the adult rat SVZ, as the mean number of sex determining region Y-box 2 and doublecortin-positive cells increased significantly, while there was a similar tendency in the subgranular zone. Collectively, these results suggest that long-term treatment with olanzapine may stimulate neurogenic stem cell formation in the SVZ which supports adult neurogenesis.