Personality traits and vulnerability to stress-induced emotional, cognitive and neural alterations in rodents
Research in humans has identified several psychosocial factors associated with both resilience to stress and stress-induced depression. In rodents, emerging evidence indicates that certain behavioral traits, such as anxiety, are also associated with the development of depression-like alterations after exposure to chronic stress. However, single traits cannot explain the wide variability observed in the vulnerability to stress in outbred populations, which led us to hypothesize that a combination of different behavioral traits might provide a better characterization of the individual’s vulnerability to be affected by prolonged stress. Hippocampal neurogenesis has been highlighted as a cellular mechanism involved in the reductions on hippocampal volume observed in the adult hippocampus under conditions of stress and depression. In our studies we investigate whether a behavioral characterization of rats’ relevant behavioral traits could help characterizing individuals showing a differential vulnerability to develop anxiety- and depression-like alterations, as well as changes in hippocampal neurogenesis, following chronic stress. Rats are characterized by means of a battery of behavioral tasks selected for their utility to evidence animal’s relevant behavioral traits. A factorial analysis identified three principal factors related to (i) anxiety, (ii) exploration/locomotion, and (iii) impulsivity traits, and a cluster analyses revealed three predominant profiles. Subsequently, half of the animals in each cluster are submitted to chronic unpredictable stress for 28 days. Our results indicate that both the direction and intensity of the impact of stress on behaviour are dependent on personality traits and correspond to different patterns of neurogenesis impairment.