Norepinephrine

Norepinephrine, known as noradrenaline outside the USA, is a catecholamine and a phenethylamine with chemical formula C8H11NO3. It is released from the adrenal glands as a hormone into the blood, but it is also a neurotransmitter in the nervous system where it is released from noradrenergic neurons during synaptic transmission. It is one of the 'stress hormones' and affects parts of the human brain where attention and impulsivity are controlled. Along with epinephrine this compound effects the fight-or-flight response, activating the sympathetic nervous system to directly increase heart rate, release energy from fat, and increase muscle readiness.

Noradrenaline metabolites

In mammals noradrenaline is rapidly degraded to various metabolites. The principle metabolites are:

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• Normetanephrine (via the enzyme COMT)
• 3,4-dihydroxymandelic acid (via monoamine oxidase, MAO)
• 3-methoxy-4-hydroxymandelic acid (via MAO)
• 3-methoxy-4-hydroxyphenylglycol (via MAO)