Experiencing early life adversity (ELA) increases the risk of anxiety disorders, such as generalized anxiety disorder and post-traumatic stress disorder, with disproportionally higher risk in women compared to men. Neurodevelopmental and behavioral outcomes following ELA are multifaceted and are influenced heavily by the type of adversity experienced and sex of the individual. A major contributor to emotional dysfunction and anxiety disorders resulting from ELA are changes in fear and threat circuitry.
Children who experienced ELA have been reported to show an accelerated development of the amygdala, a region involved in processing threat, and greater cerebrospinal levels of corticotrophin releasing hormone (Crh), an orchestrator of neuroendocrine and behavioral responses to stress. Work in rodents have linked Crh signaling within the lateral central amygdala (CeAL) with processing and responding to threat, core features disrupted in anxiety-related disorders. Further, sex biases in risk and symptom presentation have been proposed to be related to sexual dimorphic signaling of Crh across the brain that differentially influence a variety of Crh-dependent behaviors. However, it remains unclear what properties of ELA portend differential neurobiological risk, what is the basis of sex-differences for negative outcomes, and how specific mechanistic changes give rise to certain endophenotypes.
In this work, I use genetic, cellular, and behavioral approaches to explore the impact of ELA and sex on perinatal development in mice and the functional consequences of altered Crh neuron activity in the CeAL on threat responding in adulthood. In Chapter 1, I review how factors such as sex and type of ELA influence amygdala development and Crh. In Chapter 2, I assess the impact of two forms of ELA, maternal separation (MS) and limited bedding and nesting (LBN) on perinatal development and anxiety-like behavior. Both forms of ELA shifted the timing of somatic maturation and basal CORT levels and led to increased anxiety-like behaviors, but the degree of the impact depended on the sex and type of adversity experienced.
In Chapter 3, I demonstrate that a distinguishing feature between types of ELA was the predictability of maternal care. The type of ELA also contributed to sex-differences in Crh related gene expression in the perinatal amygdala. Increased expression was primarily observed in males following MS and in females following LBN. In Chapter 4, I investigate the functional consequences of ELA in the form of LBN on the activity of CeALCrh+ neurons in vivo and their causal role in threat reactivity indexed by the startle response. LBN rearing led to sustained activity of CeALCrh+ in female mice but diminished in male mice. Persistent activity of this population was necessary for and predicted the magnitude of startle responding. In Chapter 5, I discuss important considerations when integrating new advancements in the study of ELA and the use of sex as a biological variable.
Collectively, this work deepens our understanding of the neurobiological mechanisms impacted by sex and ELA and holds promise for future strategies that may consider the sex and specific experiences of the individual to target specific endophenotypes and address the underlying root causes of anxiety disorders.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/xkqk-x936 |
| Date | January 2023 |
| Creators | Demaestri, Camila |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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