- This event has passed.
PhD Transfer Exam – June (Jee) Bang (Kim lab)
May 25, 2016 @ 2:10 pm - 3:10 pm
PhD Transfer Exam
Wednesday May 25th, 2:10 pm – Ramsay Wright Building, Rm. RW 432
June (Jee) Bang (Kim lab)
“Characterization of hippocampal inhibitory circuitry of stress response and anxiety behavior using optogenetics“
Abstract
Stress initiates the release of glucocorticoid hormones (GCs) by activating hypothalamic-pituitary- adrenal (HPA) axis which then triggers diverse adaptive physiological and behavioral responses. During emotionally stressful experience, the ventral hippocampus (vHPC) is believed to attenuate the HPA-axis activity by indirectly inhibiting the paraventricular nucleus of the hypothalamus (PVN). While much effort has been made to demonstrate the inhibitory influence of vHPC on the HPA-axis during psychogenic stress, the underlying neural pathway has not been directly examined. Using the pathway specific optogenetic approach in mice, we activated vHPC inputs at the anterior hypothalamic nuclei (AHN) during a 30 min- physical restraint stress and examined its effects on stress-induced anxiety behaviours in the elevated plus maze, the successive alleys, and open field tests. We also tested whether this input can change basal anxiety level by activating the same pathway in freely moving mice with no prior stressor during the same anxiety tests. Our findings suggest that the predominantly GABAergic AHN is the functional intermediary structure through which vHPC exerts its inhibitory control on both anxiety behaviors and physiological responses such as respiration and heart rate. Together, these results show an important top-down modulation of stress response and anxiety level by the hippocampal-hypothalamic pathway as a key element in the central feedback of HPA-axis and inhibitory regulator of negative affect. We aim to further confirm our findings by measuring circulating corticosterone (CORT) level, optogenetically inactivating the vHPC-AHN pathway and by testing whether vHPC-AHN activation can rescue deleterious psychotic states such as anxiety disorder and depression-like behaviors manifested by chronic CORT exposure in mice.
Ramsay Wright is a wheelchair accessible building.