Effects of venlafaxine and chronic unpredictable stress on behavior and hippocampal neurogenesis of rat dams.

OBJECTIVE: Epidemiological studies strongly support the theory that stressful life events play an important role in the etiology of depression. The mechanism of chronic stress induced depression involves a number of systems. Chronic stress represents a serious health issue especially during pregnancy and lactation. In this sensitive period, stress can lead to changes in emotion and cognitive behavior both of the mothers and the offspring. It is thus necessary to properly manage stress events during gestation. Venlafaxine belongs to the group of serotonin and noradrenaline re-uptake inhibitor drugs. It is used for the treatment of depression, anxiety disorders and other mood disorders. During pregnancy, however, the use of venlafaxine is questionable due to the lack of experimental and clinical studies. Therefore the aim of this study was to evaluate the effect of chronic unpredictable stress and/or venlafaxine treatment on maternal and open field behavior of dams. Moreover, hippocampal neurogenesis was investigated either.

METHODS: Female Wistar rats were subjected to 2-week chronic unpredictable stress induced by random stressors and treated with venlafaxine orally at a dose of 5 mg/kg twice a day. Maternal behavior was evaluated within 5-min observations twice a day. Mothers were also tested in the open field 8 weeks after chronic unpredictable stress procedure in a single 15-min session. Hippocampal neurogenesis was investigated by immunohistochemistry essay using DCX staining.

RESULTS: Results of the present study showed altered maternal and open field behavior of the dams. Stressed dams had lowered hippocampal neurogenesis, while venlafaxine treatment reversed this lowering.

CONCLUSIONS: These results suggest that stress and antidepressant therapy can have significant impact on behavior and hippocampal neurogenesis in rat dams.