Impact of peripartum stress on postpartum maternal behavior and associated endocrine and neurobiological substrates
Date
2022
Authors
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Publisher
University of Delaware
Abstract
The purpose of this study is to measure the impact of perinatal stress on postpartum maternal behaviors and assess changes in the biological substrates associated with maternal care. We utilized a limited bedding and nesting (LBN) condition to simulate a stressful environment that mimics the stressors a new mother might experience when lacking adequate resources to care for her infant, which is a common risk factor for postpartum depression (Gifford et al., 2021). We measured the frequency of various maternal care behaviors throughout the postpartum period. We collected fecal samples to indirectly measures circulating levels of estradiol and corticosterone. We also collected brain tissues to examine hormone receptor expression in the medial preoptic area (MPOA), a brain structure necessary for maternal behavior. Our results revealed a significant effect of stress, such that LBN dams exhibited significantly decreased arched-back nursing across postnatal days (P)0 - P9 (p< 0.003), with an associated increase in simple blanket nursing across P0-P9 (p < 0.003). We found no differences in the expression of progesterone receptor, estrogen receptor (ER)-ꞵ, or oxytocin receptor in the MPOA on P2 or on P9. We found a main effect of postpartum condition on the expression of ER-ɑ in the MPOA, which was also confirmed by analysis of ER-ɑ immunohistochemistry. Specifically, and interestingly, postpartum females (both control and LBN dams) had decreased expression of ER-ɑ mRNA (p < 0.0001) and protein (p = 0.0049) in the MPOA compared to non-pregnant females. We found no differences in circulating levels of 17-β estradiol throughout the peripartum period, though we did find significant differences in the pattern of corticosterone levels during this time. We conclude that limited bedding and nesting stress decreases important arched-back nursing behavior, with no associated differences in the expression of hormone receptors in the MPOA during this time.
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Keywords
Hormone receptor expression, Corticosterone levels, Perinatal stress