Norepinephrine

Definition: Norepinephrine is both a neurotransmitter and a hormone. As a hormone, norepinephrine is released by the adrenal gland as part of the "fight-or-flight" response, resulting in increased heart rate and blood pressure. As a neurotransmitter, norepinephrine relays brain impulses from one cell to the next and is involved in arousal, attention and mood. Medications, such as serotonin norepinephrine reuptake inhibitors (SNRIs), that regulate these neurotransmitters are used in the treatment of depression, anxiety and other disorders.