The maternal-placental-fetal interface: Adaptations of the HPA axis and immune mediators following maternal stress and prenatal alcohol exposure

This review addresses underlying physiological, cellular, and molecular factors that alter the developing fetal brain stress circuits and responses of the hypothalamic-pituitary-adrenal (HPA) axis caused by maternal stress and prenatal alcohol exposure (PAE). An emphasis is placed on the contribution of the placenta following maternal stress separately, and as a co-occurrence with PAE. Altered fetal HPA axis ultimately results in dysregulation of the brain stress-response system long after birth and possibly lifelong. Additional consideration of the role of placentally-derived endocrine and sex hormones, as well as a brief discussion of epigenetic mechanisms of altered placental expression of genes encoding the glucocorticoid receptor and the enzymes 11β-HSD that rapidly convert glucocorticoids into its active or inactive forms are reviewed. Data highlighting the strong, reciprocal interactions between the neuroimmune and neuroendocrine systems during fetal development that are impacted by maternal stress and PAE are considered, emphasizing the role of the placenta as a key contributor to the dysregulation of these systems. In view of the maternal-placental-fetal interface, important physiological, cellular, and molecular factors underlying later life dysregulated stress responses are additionally considered. Literature from animal models of PAE and maternal stress is reviewed that support clinical observations of the effect of maternal stress and alcohol exposure during fetal development on later-life adult stress responses and associated mood dysregulation. An appreciation of dysregulated stress responses in individuals with fetal alcohol spectrum disorders (FASD) are addressed given the greater prevalence of adult dysregulated stress responses and a greater co-occurrence of mood disorders in individuals diagnosed with FASD.