In panic disorder there is increased noradrenaline transmission from both the locus coeruleus and the caudal raphe nuclei. The locus coeruleus-noradrenaline system may have a significant role in processing fear-related stimuli or it may affect fear-related processing by stimulating other regions of the brain implicated in anxiety and fear behaviours ie amygdala, hippocampus, hypothalamus, cortex and spinal cord.
The principal serotonin centres in the brain are the caudal and rostral raphe nuclei. Transmission of serotonin from the rostral raphe nuclei to the pre-aquaductal grey, amygdala, temporal lobe and limbic cortex is decreased in panic disorder compared with normal. Serotonin transmission to other target regions of the brain remain unchanged.