CRH and Anxiety: When stimulated by stressors, the 5-HT neuronal system of the DRN-BNST circuit is excited, which affects the neuronal activity of the 5-HT neurons projecting to BNST in the brain, causing expression changes in central nervous system neurotransmitters (including 5-HT), CRF, and receptors, leading to changes in the circuit information cascade response, regulating anxiety and fear behavior and processes (Daniel and Rainnie, 2016).