Date of Award
Campus Access Dissertation
Doctor of Philosophy (PhD)
Developmental and Brain Sciences
Celia L. Moore
Richard G. Hunter
Early experiences are fundamental for social, cognitive, and behavioral development. Caregivers, particularly mothers, play an essential role in this development. The mother-infant relationship is characterized by reciprocal, regulatory, and dynamic processes which determine developmental trajectory of the young. The predictable nature in onset and progression of some behaviors in development ensures offspring survival while permitting a degree of modification to more precisely determine developmental trajectory. Modifiers of early experiences include individual and intergenerational life history of the mother, peers, paternal effects, and environmental contributions. This dissertation explores the effects of some of these modifiers on offspring development. The first study identifies multiple sources of individual variation in hypothalamic-pituitary-adrenal (HPA) axis response to stress in human participants and highlights HPA dysregulation that can result from historical and concurrent toxic stress. Next, the effects of early experience on development of central oxytocin systems related to HPA regulation (paraventricular nucleus of the hypothalamus, amygdala, hippocampus) were investigated in Long-Evans rats using an environmental manipulation, limited bedding and nesting material (LBN), to change early life experience. Effects on central oxytocin were age, sex, and region specific, and generally increased the number of oxytocin and oxytocin receptor cells in females and decreased the number in males. These changes were accompanied by changes in social interaction and behavioral social buffering in LBN females. A separate analysis assessed lineage and LBN effects on maternal behavior in dams from three lineages. This data provides evidence of inter-lineage variability that is greater than inter-condition variability for some maternal behaviors which demonstrates limitations in maternal behavior plasticity within a single generation. Finally, LBN effects on pup behavioral and physiological indices of thermal regulation were assessed to determine if LBN presents a thermal challenge to pups. LBN pups had disrupted huddling and changes in physiological markers of thermogenesis: brown adipose tissue activation and mitochondria biogenesis. There were also sex differences between control males and females and between LBN males and females. Together, these data emphasize the importance of multiple inputs in determining developmental trajectory during early life and raises new questions about resilience and vulnerability to stress within and between generations.
Lapp, Hannah E., "Environmental Disruption of the Developmental System During Early Life" (2019). Graduate Doctoral Dissertations. 486.