NR3C1 and depressive disorder: The hippocampus is the most commonly studied brain region in depression research, on the one hand, the hippocampus is a part of the limbic system, forming nerve fiber connections with emotion related brain regions such as the prefrontal cortex and amygdala; on the other hand, the hippocampus contains high levels of glucocorticoid receptors and glutamate, and regulates the hypothalamic pituitary adrenal (HPA) axis, making it more susceptible to stress and depression (60).