Page last updated: 2024-10-24

norepinephrine secretion

Definition

Target type: biologicalprocess

The regulated release of norepinephrine by a cell. Norepinephrine is a catecholamine and it acts as a hormone and as a neurotransmitter of most of the sympathetic nervous system. [GOC:ef, GOC:jid]

Norepinephrine secretion is a complex process that involves the synthesis, storage, and release of norepinephrine from sympathetic nerve terminals.

**Synthesis:** Norepinephrine is synthesized from the amino acid tyrosine. Tyrosine is converted to L-DOPA by the enzyme tyrosine hydroxylase. L-DOPA is then converted to dopamine by the enzyme aromatic L-amino acid decarboxylase. Finally, dopamine is converted to norepinephrine by the enzyme dopamine β-hydroxylase.

**Storage:** Norepinephrine is stored in synaptic vesicles within the nerve terminal. These vesicles are filled with norepinephrine and other neurotransmitters, such as ATP and chromogranin A.

**Release:** When a nerve impulse arrives at the nerve terminal, calcium ions enter the terminal and trigger the fusion of synaptic vesicles with the presynaptic membrane. This fusion releases norepinephrine into the synaptic cleft, the space between the nerve terminal and the target cell.

**Reuptake:** After release, norepinephrine is rapidly removed from the synaptic cleft by reuptake into the presynaptic nerve terminal. This reuptake is mediated by a specific transporter protein called the norepinephrine transporter (NET).

**Regulation:** Norepinephrine secretion is regulated by a variety of factors, including neuronal activity, stress, and the presence of other neurotransmitters. For example, the release of norepinephrine is increased by the activation of β-adrenergic receptors, while it is decreased by the activation of α2-adrenergic receptors.

**Biological Roles:** Norepinephrine is a neurotransmitter that plays a wide variety of roles in the body, including:

* **Regulation of heart rate and blood pressure:** Norepinephrine increases heart rate and blood pressure by stimulating the sympathetic nervous system.
* **Regulation of mood and arousal:** Norepinephrine is involved in the regulation of mood, attention, and alertness.
* **Regulation of sleep and wakefulness:** Norepinephrine plays a role in the regulation of sleep-wake cycles.
* **Regulation of energy metabolism:** Norepinephrine stimulates the breakdown of glycogen and fat, increasing energy expenditure.
* **Regulation of pain perception:** Norepinephrine can block pain signals.

**Disorders:** Disruptions in norepinephrine secretion can lead to a number of disorders, including:

* **Depression:** Low levels of norepinephrine are associated with depression.
* **Anxiety:** High levels of norepinephrine are associated with anxiety.
* **Post-traumatic stress disorder (PTSD):** Dysregulation of norepinephrine levels is associated with PTSD.
* **Attention-deficit/hyperactivity disorder (ADHD):** Disruptions in norepinephrine levels are associated with ADHD.'
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Proteins (1)

ProteinDefinitionTaxonomy
Catechol O-methyltransferaseA catechol O-methyltransferase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P21964]Homo sapiens (human)

Compounds (8)

CompoundDefinitionClassesRoles
oxyquinolineOxyquinoline: An antiseptic with mild fungistatic, bacteriostatic, anthelmintic, and amebicidal action. It is also used as a reagent and metal chelator, as a carrier for radio-indium for diagnostic purposes, and its halogenated derivatives are used in addition as topical anti-infective agents and oral antiamebics.

quinolin-8-ol : A monohydroxyquinoline that is quinoline substituted by a hydroxy group at position 8. Its fungicidal properties are used for the control of grey mould on vines and tomatoes.
monohydroxyquinolineantibacterial agent;
antifungal agrochemical;
antiseptic drug;
iron chelator
verapamil2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile : A tertiary amino compound that is 3,4-dimethoxyphenylethylamine in which the hydrogens attached to the nitrogen are replaced by a methyl group and a 4-cyano-4-(3,4-dimethoxyphenyl)-5-methylhexyl group.

verapamil : A racemate comprising equimolar amounts of dexverapamil and (S)-verapamil. An L-type calcium channel blocker of the phenylalkylamine class, it is used (particularly as the hydrochloride salt) in the treatment of hypertension, angina pectoris and cardiac arrhythmia, and as a preventive medication for migraine.

Verapamil: A calcium channel blocker that is a class IV anti-arrhythmia agent.
aromatic ether;
nitrile;
polyether;
tertiary amino compound
8-hydroxyquinoline-5-sulfonic acid8-hydroxyquinoline-5-sulfonic acid: RN given refers to parent cpd
5'-methylthioadenosine5'-methylthioadenosine: structure

5'-S-methyl-5'-thioadenosine : Adenosine with the hydroxy group at C-5' substituted with a methylthio (methylsulfanyl) group.
thioadenosinealgal metabolite;
Escherichia coli metabolite;
human metabolite;
mouse metabolite;
Saccharomyces cerevisiae metabolite
sitagliptinsitagliptin : A triazolopyrazine that exhibits hypoglycemic activity.triazolopyrazine;
trifluorobenzene
EC 3.4.14.5 (dipeptidyl-peptidase IV) inhibitor;
environmental contaminant;
hypoglycemic agent;
serine proteinase inhibitor;
xenobiotic
tolcaponetolcapone : Benzophenone substituted on one of the phenyl rings at C-3 and C-4 by hydroxy groups and at C-5 by a nitro group, and on the other phenyl ring by a methyl group at C-4. It is an inhibitor of catechol O-methyltransferase.

Tolcapone: A benzophenone and nitrophenol compound that acts as an inhibitor of CATECHOL O-METHYLTRANSFERASE, an enzyme involved in the metabolism of DOPAMINE and LEVODOPA. It is used in the treatment of PARKINSON DISEASE in patients for whom levodopa is ineffective or contraindicated.
2-nitrophenols;
benzophenones;
catechols
antiparkinson drug;
EC 2.1.1.6 (catechol O-methyltransferase) inhibitor
entacaponeentacapone : A monocarboxylic acid amide that is N,N-diethylprop-2-enamide in which the hydrogen at position 2 is substituted by a cyano group and the hydrogen at the 3E position is substituted by a 3,4-dihydroxy-5-nitrophenyl group.

entacapone: structure given in first source
2-nitrophenols;
catechols;
monocarboxylic acid amide;
nitrile
antidyskinesia agent;
antiparkinson drug;
central nervous system drug;
EC 2.1.1.6 (catechol O-methyltransferase) inhibitor
opicaponeopicapone: structure in first sourceoxadiazole;
ring assembly