Adrenaline (also known as epinephrine) is a hormone and neurotransmitter. It is primarily produced in the adrenal glands and certain neurons in humans and animals.[clarification needed]
Adrenaline is used to regulate heart rate, blood vessel and air passage diameters, and metabolic shifts. Adrenaline release is a crucial component of the fight-or-flight response of the sympathetic nervous system.
Adrenaline is a phenethylamine and catecholamine, which is a monoamine chain attached to a benzene ring. The catechol ring is a benzene ring with two hydroxyl groups attached to it, where both are ortho-oriented relative to each other. A monoamine chain is made up of an amine group attached to an ethane chain. This monoamine chain can be found in many neurotransmitters, including histamine, dopamine, serotonin and noradrenaline. It is also found in many psychoactive substances, examples being tryptamines and phenethylamines.
The adrenergic receptors exhibit both excitatory and inhibitory neurotransmission and are located throughout the human body. There are two types of adrenaline receptors; α(1 or 2) and β(1-3).
Drugs targeting the adrenergic system
- Direct-acting agonists
Direct-acting agonists have direct action upon the adrenergic system where they have action upon the adrenergic receptors themselves. These include antihypertensives (to reduce blood pressure), sedatives and muscle relaxants.
- Indirect-acting agonists
Indirect agonists work by increasing the neurotransmission of endogenous chemicals such as adrenaline or noradrenaline. These include many stimulant drugs, such as amphetamine, cocaine, MDMA and methylphenidate.
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