L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase (also known as DOPA decarboxylase), with pyridoxal phosphate as a cofactor. Conversion of tyrosine to L-DOPA is inhibited by Metyrosine, a tyrosine analog. Tyrosine is converted into L-DOPA by the enzyme tyrosine hydroxylase, with tetrahydrobiopterin, O 2, and probably ferrous iron (Fe 2+) as cofactors.
![locked heart drawing locked heart drawing](https://i.pinimg.com/originals/2e/d2/1d/2ed21de6bbc9c83f6d4dba1fbeb15616.jpg)
Phenylalanine is converted into tyrosine by the enzyme phenylalanine hydroxylase, with molecular oxygen (O 2) and tetrahydrobiopterin as cofactors. These amino acids are found in nearly every protein and, as such, are provided by ingestion of protein-containing food, with tyrosine being the most common. Thus the direct precursor of norepinephrine is dopamine, which is synthesized indirectly from the essential amino acid phenylalanine or the non-essential amino acid tyrosine. Phenylalanine → Tyrosine → L-DOPA → Dopamine → Norepinephrine While the conversion of tyrosine to dopamine occurs predominantly in the cytoplasm, the conversion of dopamine to norepinephrine by dopamine β-monooxygenase occurs predominantly inside neurotransmitter vesicles.
#LOCKED HEART DRAWING SERIES#
Norepinephrine is synthesized from the amino acid tyrosine by a series of enzymatic steps in the adrenal medulla and postganglionic neurons of the sympathetic nervous system. Norepinephrine is synthesized from dopamine in the human body by the dopamine β-hydroxylase (DBH) enzyme. Norepinephrine consists of a catechol moiety (a benzine ring with two adjoining hydroxyl groups in the meta-para position), and an ethylamine side chain consisting of a hydroxyl group bonded in the benzylic position. The prefix nor- is derived as an abbreviation of the word "normal", used to indicate a demethylated compound. 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. Norepinephrine is a catecholamine and a phenethylamine. Many important psychiatric drugs exert strong effects on noradrenaline systems in the brain, resulting in side-effects that may be helpful or harmful. Alpha-2 agonists often have a sedating effect and are commonly used as anesthesia-enhancers in surgery, as well as in treatment of drug or alcohol dependence. Alpha blockers, which counter a different set of noradrenaline effects, are used to treat several cardiovascular and psychiatric conditions. Beta blockers, which counter some of the effects of noradrenaline by blocking their receptors, are frequently used to treat glaucoma, migraine, and a range of cardiovascular problems. Noradrenaline itself is widely used as an injectable drug for the treatment of critically low blood pressure. Regardless of how and where it is released, norepinephrine acts on target cells by binding to and activating adrenergic receptors located on the cell surface.Ī variety of medically important drugs work by altering the actions of noradrenaline systems. It is also released directly into the bloodstream by the adrenal glands. Outside the brain, norepinephrine is used as a neurotransmitter by sympathetic ganglia located near the spinal cord or in the abdomen, as well as Merkel cells located in the skin. The most important of these nuclei is the locus coeruleus, located in the pons. In the brain, noradrenaline is produced in nuclei that are small yet exert powerful effects on other brain areas. In the rest of the body, norepinephrine increases heart rate and blood pressure, triggers the release of glucose from energy stores, increases blood flow to skeletal muscle, reduces blood flow to the gastrointestinal system, and inhibits voiding of the bladder and gastrointestinal motility. 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. Regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as noradrenergic.
![locked heart drawing locked heart drawing](https://i.pinimg.com/originals/dc/d5/67/dcd567e86ff94f63d345796b4c28a9c0.jpg)
"Norepinephrine" is also the international nonproprietary name given to the drug. The name "noradrenaline" (from Latin ad, "near", and ren, "kidney") is more commonly used in the United Kingdom, whereas "norepinephrine" (from Ancient Greek ἐπῐ́ ( epí), "upon", and νεφρός ( nephrós), "kidney") is usually preferred in the United States. Norepinephrine ( NE), also called noradrenaline ( NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter.