Stress exposure stimulates the release of corticotropin releasing hormone (CRH) in the brain and activates the hypothalamus-pituitary-adrenal (HPA) axis, which is key mechanism of stress regulation. Research into the role of CRH in stress has advanced rapidly in the past 40 years since it was first characterized in 1981 (Vale et al., 1981). While the CRH-dependent HPA activation is undisputed, the role for CRH derived from sources other than the PVN remains largely unknown with inconsistent evidences. Recently, our lab has successfully generated the CRHflox mice which allow us to site-specifically delete the CRH through Cre recombinase, which provide us an elegant tool to clarify the role of CRH in different area. Our central hypothesis is that dysregulation of central amygdala (CeA) CRH is responsible for the stress-induced Depression by assessing the genetic and environmental risk factors. The hypothesis will be tested by the completion of 3 Specific Aims.
Specific Aim 1 will test the hypothesis that CeA CRH system is required for the activation of HPA responsivity to psychogenic stressor but not systemic stressor. We predict that the loss of CRH from the CeA will attenuate the HPA responsivity to dirty cage exposure but not to hypoxia stress exposure.
Specific Aim 2 will test the hypothesis that stress-induced insomnia is mediated through the CeACRH and noradrenergic pathway in LC is involved. We predict that deletion of the CeA CRH will attenuate the stress emotion-associated insomnia.
Specific Aim 3 will test the hypothesis that CeA CRH is necessary for regulating stress-induced depression.
This aim will assess the role of CeA CRH in acute stress responses (adaptation) and prolonged stress-associated vulnerability (maladaptation). The accomplishment of this study will illuminate the CRH-mediated neuronal circuitry underlying the depression, particularly for insomnia, a hallmark for affective diseases, and lead us to find a potential preventive or therapeutic approach to treat insomnia, thus, alleviate mental disorders. This Career Development Award (K01) will provide the candidate with the necessary skills to develop an independent research program focused on molecular mechanism of stress regulation. The training plan is designed to provide the candidate with skills in circadian biology and sleep regulation, psychophysiology and psychopathology, and genetic epidemiology which are critical in my chosen area of study. Specially, the candidate will acquire the knowledge and skills to 1) conduct the gene-modified research to identify the neuropathway underlying the mood and anxiety disorders 2) design, conduct and analyze stress-associated insomnia research. These skills will be developed through a combination of didactic training, guided readings and mentored research projects. Research results and training activities will be used to develop a R01 proposal for a prospective study that assesses both genetic and environmental risk factors and aims to identify the potential molecular targets for stress- related disease states.
Stressful life events often precede anxiety disorders, and the first depressive episode often develops following the occurrence of a major negative life event. The proposed research aims to identify the mechanisms of the genetic and environmental risk factors utilizing corticotropin-releasing hormone that underlying the onset of mood and sleep disorders. Elucidation of these mechanisms, and the role of genetic vulnerability that alter mediating pathways, is critical to development of therapeutic or preventative strategies to combat stress-induced depression. Given that the depression is a serious neuropsychiatric illness and greatest public health burden http://www.nimh.nih.gov/statistics/4COST_AM2006.shtml, undertaking this study represents an important public priority.