Long-term programming of enhanced aggression by peripuberty stress in female rats

Abstract

Summary Human literature has linked adverse early life experiences with an increased risk to develop violent behaviors in both boys and girls. We have previously shown that male rats submitted to stress during the peripuberty period display as adults abnormal aggressive behavior against both male intruders and female partners. In the present study, we examined whether the same stress protocol would affect the development of aggressive behaviors in female rats. We evaluated the behavior of these peripuberty stressed female rats when confronted, at adulthood, with either female or male intruders, and during their cohabitation with male partners. Given that estrus cycle influences mood and aggressive behaviors, female aggressive behavior was assessed at different estrus cycle phases: estrus and diestrus, and during pregnancy and lactancy. Additionally, we evaluated postpartum plasma levels of vasopressin, oxytocin and corticosterone, hormones associated with aggression and the regulation of social behavior. Compared to control females, females submitted to stressful events during puberty exhibited higher and more sustained rates of aggression during adulthood independently on the estrus cycle or the sex of the intruder, and they had higher levels of plasma vasopressin. Significant correlations between plasma levels of vasopressin and corticosterone and aggressive behavior were also found. Strikingly, our results showed opposite intragroup correlations suggesting a different role of these hormones on aggression depending on life experiences. We provide here an animal model, devoid of cultural influences strongly supporting a role for biological factors in the development of aggressive behaviors following exposure to stressful events at puberty in females. #

Staphylococcal enterotoxin B administration during pregnancy imprints the increased CD4:CD8 T-cell ratio in the peripheral blood from neonatal to adult offspring rats

“…Pregnant adverse stimulus including physico-chemical and biological factors during fetal development may induce long-term structural and functional effects and yield programming/imprinting effects to cause diseases (Kaplan et al, 2011;Ruchat et al, 2013;Cordero et al, 2013;Vickers, 2014;Kilcoyne et al, 2014;Krow-Lucal et al, 2014). The present study revealed that prenatal exposure to SEB significantly increases the CD4:CD8 T-cell ratio through the decrease of CD8 T cells and the increase of CD4 T cells in the peripheral blood of both neonatal and adult offspring rats.…”

Effects of aging on stress-related responses of serotonergic neurons in the dorsal raphe nucleus of male rats

“…Adverse experiences in early life such as neonatal maternal separation cause long-lasting behavioral and psychological effects, and the effects of neonatal experience can remain detectable in the aged (Akers et al., 2008, Arborelius and Eklund, 2007). Neonatal and pubertal stress experiences have no small effect on the development and maturation of the HPA axis, and cause organizational effects resulting in changes in emotional function and the stress response (Cordero et al., 2013, Romeo, 2010, Romeo, 2003). Our findings showed the long-term influence of stress experience in young adulthood on stress responses in old age.…”

Peripubertal stress-induced behavioral changes are associated with altered expression of genes involved in excitation and inhibition in the amygdala

“…For this reason, we did not explicitly include a cohort exposed to stress during the intermediate period comprising P34 and P36, which corresponds to the onset of puberty in female rats. However, as female rats exposed to the Full Peripubertal Stress also develop increased aggression, 59 it will be important in future studies to investigate potential sex differences linked to the timing and chronicity of stress exposure during the developmental periods under study.…”