Gating of the neuroendocrine stress responses by stressor salience in early lactating female rats is independent of infralimbic cortex activation and plasticity.

TitleGating of the neuroendocrine stress responses by stressor salience in early lactating female rats is independent of infralimbic cortex activation and plasticity.
Publication TypeJournal Article
Year of Publication2018
AuthorsHillerer KM, Woodside B, Parkinson E, Long H, Verlezza S, C-D Walker
JournalStress
Volume21
Issue3
Pagination217-228
Date Published2018 May
ISSN1607-8888
Abstract

In early lactation (EL), stressor salience modulates neuroendocrine stress responses, but it is unclear whether this persists throughout lactation and which neural structures are implicated. We hypothesized that this process is specific to EL and that the infralimbic (IL) medial prefrontal cortex (mPFC) might provide a critical link between assessment of threat and activation of the hypothalamo-pituitary-adrenal (HPA) axis in EL. We measured neuroendocrine responses and neuronal Fos induction to a salient (predator odor) or non-salient (tail pinch) psychogenic stressor in EL and late lactation (LL) females. We found that EL females exhibited a large response to predator stress only in the presence of pups, while responses to tail pinch were reduced independently of pup presence. In LL, HPA axis responses were independent of pup presence for both stressors and only responses to tail pinch were modestly reduced compared to virgins. Intracerebral injection of the local anesthetic bupivacaine (BUP) (0.75%; 0.5 µl/side) in the IL mPFC did not differentially affect neuroendocrine responses to predator odor in virgin and EL females, suggesting that lactation-induced changes in this structure might not regulate stressor salience for the HPA axis. However, the IL mPFC displayed morphological changes in lactation, with significant increases in dendritic spine numbers and density in EL compared to LL and virgin females. EL females also showed improved performance in the attention set-shifting task (AST), which could reflect early plasticity in the IL mPFC at a time when rapid adaptation of the maternal brain is necessary for pup survival.

DOI10.1080/10253890.2018.1434618
Alternate JournalStress
PubMed ID29397787