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Information about Catecholamine

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tyrosine is the precursor of catecholamines
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norepinephrine
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dopamine
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Synthesis
Catecholamines are chemical compounds derived from the amino acid tyrosine containing catechol and amine groups. Some of them are biogenic amines. Catecholamines are water soluble and are 50% bound to plasma proteins, so they circulate in the bloodstream. The most abundant catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine, all of which are produced by phenylalanine and tyrosine. Tyrosine is created from phenylalanine by hydroxylation thanks to the enzyme, phenylalanine hydroxylase (tyrosine is also ingested directly from dietary protein). Tyrosine is then sent to catecholamine secreting neurons. Here many kinds of reactions convert it to dopamine, to norepinephrine and epinephrine eventually.[1] Catecholamines as hormones are released by the adrenal glands in situations of stress such as psychological stress or low blood sugar levels[2].

Production

Catecholamines are produced mainly by the chromaffin cells of the adrenal medulla and the postganglionic fibers of the sympathetic nervous system. Dopamine, which acts as a neurotransmitter in the central nervous system, is largely produced in neuronal cell bodies in two areas of the brainstem: the substantia nigra and the ventral tegmental area.

Function

Modality

Two catecholamines, norepinephrine and dopamine, act as neurotransmitters in the central nervous system and as hormones in the blood circulation. The catecholamine norepinephrine is a neurotransmitter of the peripheral sympathetic nervous system but is also present in the blood (mostly through "spillover" from the synapses of the sympathetic system).

High catecholamine levels in blood are associated with stress, which can be induced from psychological reactions or environmental stressors such as elevated sound levels, intense light, or low blood sugar levels.

Extremely high levels of catecholamine (also known as catecholamine toxicity) can occur in CNS trauma due to stimulation and/or damage of nuclei in the brainstem, particularly those nuclei affecting the sympathetic nervous system. In emergency medicine, this occurrence is widely known as catecholamine dump.

Effects

Catecholamines cause general physiological changes that prepare the body for physical activity (fight-or-flight response). Some typical effects are increases in heart rate, blood pressure, blood glucose levels, and a general reaction of the sympathetic nervous system. Some drugs, like tolcapone (a central COMT-inhibitor), raise the levels of all the catecholamines.

Structure

Catecholamines have the distinct structure of a benzene ring with two hydroxyl groups, an intermediate ethyl chain and a terminal amine group.

Degradation

They have a half-life of approximately a few minutes when circulating in the blood.

Monoamine oxidase (MAO) is the main enzyme responsible for degradation of catecholamines.

Methamphetamine and MAOIs bind to MAOs to inhibit their action of breaking down catecholamines. This is primarily the reason why the effects of amphetamines last longer than cocaine and other substances. Amphetamines not only causes a release of dopamine, epinephrine, and norepinephrine into the blood stream, but also keeps it working there for a long time.

See also

References

1. ^ [1]
2. ^ "Hypoglycemia" by Ronald Hoffman, M.D., July 1999, The Holistic M.D.

External links

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amino acid is a molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent.
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Tyrosine (abbreviated as Tyr or Y)[1] or 4-hydroxyphenylalanine, is one of the 20 amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid and it is found in large quantities in casein.
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Pyrocatechol, more commonly known as catechol, is a benzenediol, with the formula C6H4(OH)2.

Isolation, synthesis

Catechol was first isolated in 1839 by H.
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Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. Structurally amines resemble ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups.
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A biogenic amine is a biogenic substance with an amine group. Some prominent examples of biogenic amines include:
  • Histamine - a substance derived from the amino acid histidine that acts as a neurotransmitter mediating arousal and attention, as well as a pro-inflammatory signal

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Epinephrine (INN) (IPA: [ˌɛpɪˈnɛfrən]) or adrenaline (European Pharmacopoeia and BAN) (IPA: [əˈdrɛnələn]
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Norepinephrine (INN)(abbr. norepi or NE) or noradrenaline (BAN) is a catecholamine and a phenethylamine with chemical formula C8H11NO3. The natural stereoisomer is L -(−)-(R)-norepinephrine.
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Dopamine is a hormone and neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In chemical structure, it is a phenethylamine.
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hormone (from Greek όρμή - "to set in motion") is a chemical messenger that carries a signal from one cell (or group of cells) to another. All multicellular organisms produce hormones (including plants - see phytohormone).
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In mammals, the adrenal glands (also known as suprarenal glands) are the triangle-shaped endocrine glands that sit on top of the kidneys; their name indicates that position (ad-, "near" or "at" + -renes, "kidneys").
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The fight-or-flight response, also called hyperarousal or the acute stress response, was first described by Walter Cannon in 1915[1][2].
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MeSH D007003 Hypoglycemia (hypoglycaemia in British English) is a medical term referring to a pathologic state produced by a lower than normal level of glucose (sugar) in the blood. The term hypoglycemia literally means "under-sweet blood" (Gr.
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Chromaffin cells are neuroendocrine cells found in the medulla of the adrenal gland and in other ganglia of the sympathetic nervous system. They are derived from the embryonic neural crest.
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adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex.

Function

Composed mainly of hormone-producing chromaffin cells, the adrenal medulla is the principal site of the conversion of the amino acid
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postganglionic fibers.

Neurotransmitters

The neurotransmitters used for postganglionic fibers differ:
  • In the parasympathetic division, they are cholinergic (that is, they use acetylcholine as their neurotransmitters.

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The Sympathetic Nervous System (SNS) is a branch of the autonomic nervous system. It is always active at a basal level (called sympathetic tone) and becomes more active during times of stress.
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Dopamine is a hormone and neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In chemical structure, it is a phenethylamine.
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Neurotransmitters are chemicals that are used to relay, amplify and modulate signals between a neuron and another cell. According to the prevailing beliefs of the 1960s, a chemical can be classified as a neurotransmitter if it meets the following conditions:

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The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behavior.
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The substantia nigra (Latin for "black substance", Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system.
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The ventral tegmentum or the ventral tegmental area (VTA) (tegmentum, Latin for covering) is part of the midbrain, lying close to the substantia nigra and the red nucleus.
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Norepinephrine (INN)(abbr. norepi or NE) or noradrenaline (BAN) is a catecholamine and a phenethylamine with chemical formula C8H11NO3. The natural stereoisomer is L -(−)-(R)-norepinephrine.
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Dopamine is a hormone and neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In chemical structure, it is a phenethylamine.
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Neurotransmitters are chemicals that are used to relay, amplify and modulate signals between a neuron and another cell. According to the prevailing beliefs of the 1960s, a chemical can be classified as a neurotransmitter if it meets the following conditions:

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The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behavior.
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Norepinephrine (INN)(abbr. norepi or NE) or noradrenaline (BAN) is a catecholamine and a phenethylamine with chemical formula C8H11NO3. The natural stereoisomer is L -(−)-(R)-norepinephrine.
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synapse. Synapses allow nerve cells to communicate with one another through axons and dendrites, converting electrical impulses into chemical signals.]]

Chemical synapses
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Noise health effects, the collection of health consequences of elevated sound levels, constitute one of the most widespread public health threats in industrialized countries. Roadway noise is the main source of environmental noise exposure.
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