Early prenatal but not postnatal glucocorticoid exposure is associated with enhanced HPA axis activity into adulthood in a wild primate

The hypothalamic-pituitary-adrenal (HPA) axis plays a dual role in the
biology of developmental plasticity in mammals including humans — HPA axis
activity not only provides the input for, but is also a target of,
offspring developmental plasticity. To investigate the understudied
effects of exposure timing, this study quantified maternal HPA axis
activity during each half of gestation as well as during early lactation
and assessed its effect on offspring HPA axis activity in a
cross-sectional sample of infant, juvenile, and adult Assamese macaques
(Macaca assamensis). To add ecological validity to experimental studies
under lab conditions, macaques were studied in the wild. Increased
maternal fecal glucocorticoid metabolite levels experienced early in
gestation, but not postnatal exposure during lactation were associated
with increased offspring HPA axis activity from infancy into adulthood.
Building on prior findings, this study indicates that significant timing
effects not only influence the presence, magnitude, and direction, but
also the consistency of maternal glucocorticoid effects on offspring HPA
axis function.