Background: Studies have shown that both maternal and non-maternal environmental influences affect the development of the hypothalamic-pituitary-adrenal (HPA) axis. It remains unclear how these influences jointly interact to program offspring HPA function. Here, we test the hypothesis that non-maternal environmental effects on offspring HPA function depend contextually on maternal self-stress regulation. Methods: To examine individual differences in maternal self-stress regulation, mothers basal circulating and evoked corticosterone (CORT) response were measured shortly after weaning. The effects of the non-maternal environment were assessed by employing both the neonatal and the early adulthood novelty exposure procedures. The neonatal novelty exposure procedure occurred from post-natal day 1-20. Half the pups in a cohort of rat families were exposed to a novel, non-home environment daily for 3-min (Novel, N=49 males), while their siblings remained in the home cage (Home, N=45 males). From post- natal day 54-63, a subset of each neonatal group was exposed to early adulthood novelty exposure, in which the pups were exposed to a novel, non-home environment for 3-min iii daily (Novel, N=49), while their siblings remained in their home cage (Home, N=45). Offspring self-stress regulation was measured in mid-adulthood (13 months of age). Results: Compared to their Home siblings, neonatal Novel rats displayed a significantly higher initial evoked CORT response following a stressor. More importantly, maternal self-stress regulation interacted with this observed neonatal novelty exposure effect such that greater novelty-induced enhancement was found among offspring of mothers who were able to mount a larger evoked CORT response. Conclusions: These findings support the maternal modulation hypothesis suggesting that the effects of early non-maternal environmental novelty on offspring HPA function is modulated by the context set by individual differences in maternal physiology. These results offer converging evidence with previously reported interaction effects found in spatial memory, behavioral inhibition, and early growth.
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maternal, exposure to novelty, stress
Dinces, Sarah. "Maternal modulation of the experience of novelty on offspring hormonal stress reactivity." (2013). http://digitalrepository.unm.edu/psy_etds/35