Reuptake into the presynaptic terminal occurs via the norepinephrine transporter (NET), and then the transmitter is either degraded within the cell by MAO or COMT or repackaged into synaptic vesicles. Termination of norepinephrine signaling is similar to the termination of dopamine signaling. Therefore, unlike the other small molecule neurotransmitters, norepinephrine is synthesized within the vesicles, not in the cytoplasm. Norepinephrine is used clinically as a means of maintaining blood pressure in certain types of shock (e.g., septic shock). The neurotransmitter noradrenaline also reaches your adrenal gland, which releases the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). Norepinephrine, also called noradrenaline, is both a neurotransmitter and a hormone. While epinephrine has slightly more of an effect on your heart, norepinephrine has more of an effect on your blood vessels. However, norepinephrine can also make your blood vessels become narrower, increasing blood pressure. Norepinephrine can also cause your blood vessels to narrow, which increases blood pressure. In some cases it is difficult to distinguish the norepinephrine-mediated effects from the effects related to other neurotransmitters.citation needed Amphetamine, for example, is a stimulant that increases release of norepinephrine as well as dopamine. These are sympathomimetic drugs that activate alpha-2 receptors or enhance their effects. In the brain, norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, and focuses attention; it also increases restlessness and anxiety. Norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response. The general function of norepinephrine is to mobilize the brain and body for action. The name "norepinephrine" (from Ancient Greek ἐπῐ́ (epí), "upon", and νεφρός (nephrós), "kidney") is usually preferred in the United States, whereas "noradrenaline" (from Latin ad, "near", and ren, "kidney") is more commonly used in the United Kingdom and the rest of the world. Norepinephrine is part of your sympathetic nervous system, which is part of your body’s emergency response system to danger — the "fight-or-flight" response. As a neurotransmitter, norepinephrine is made from dopamine. Norepinephrine, also known as noradrenaline, is both a neurotransmitter and a hormone. After synthesis, norepinephrine is transported from the cytosol into synaptic vesicles by the vesicular monoamine transporter (VMAT). Alpha-1 receptors and all three types of beta receptors usually have excitatory effects. All of these function as G protein-coupled receptors, meaning that they exert their effects via a complex second messenger system. Its structure differs from that of epinephrine only in that epinephrine has a methyl group attached to its nitrogen, whereas the methyl group is replaced by a hydrogen atom in norepinephrine. Drugs such as cocaine and methylphenidate act as reuptake inhibitors of norepinephrine, as do some antidepressants, such as those in the SNRI class. Both effects of NE were negated by the addition of the beta-adrenoceptor antagonist propranolol but not by the alpha-adrenoceptor antagonist phentolamine.
