Behavioral and neurodevelopmental effects of stressful and ambivalent early life events

There are clinical and epidemiological evidence for the negative effects of early adverse life events on neurobiological and psychosocial development of children, and they are risk factors for the development of psychiatric disorders in adulthood. The purpose of this study was to investigate the effects of different early adverse life events on adulthood anxiety and depression levels, as well as memory functions and neurogenesis in rats. With this purpose, rats were grouped in four: (1) Control group (n=12), rats which were raised with standard care; (2) Mild stress group (n=16), rats which were raised by using Early Handling model; (3) Severe stress group (n=13), rats which were raised by using Early Deprivation model; (4) Ambivalent mother group (n=17), rats which spent 3 hours/day with a ?fake mother?. In adulthood, their behavioral analysis and ultrasonic vocalization recordings were made, their anxiety and depression levels, and their memory functions were evaluated by using Elevated Plus Maze, Forced Swim Test, and New Object Recognition Test. For neurodevelopmental analysis, their BDNF levels in prefrontal cortex, dentate gyrus and cerebellum were evaluated by using Western Blott and ELISA. According to behavioral analysis and anxiety model, female rats in severe stress and ambivalent mother groups had significantly lower anxiety levels than control and mild stress groups. Regardless of gender, rats in severe stress and ambivalent mother groups had significantly lower levels of depressive like behavior. There were no statistically significant differences between four groups with regard to memory functions and BDNF levels. In contrary to our hypothesis, these results show that in rats early severe stressful events and being raised by an ambivalent mother decrease anxiety and depression levels in adulthood. Future research conducted by using different modifications of the ?fake mother? model, which does not exist in previous literature and was used first in this research, would increase the reliability and validity of this model.