Norepinephrine (INN An International Nonproprietary Name is the official non-proprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization (WHO)[citation needed]. The plethora of named proprietary preparations containing a given substance can lead to confusion about the identity of the active ingredient. INNs) (abbreviated norepi or NE) or noradrenaline (BAN A British Approved Name is the official non-proprietary or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia (BP). The BAN is also the official name used in many countries across the world, especially those of the Commonwealth of Nations[citation needed]) (abbreviated NA or NAd) is a catecholamine Catecholamines are sympathomimetic "fight-or-flight" hormones released by the adrenal glands in response to stress. They are part of the sympathetic nervous system with multiple roles including as a hormone A hormone is a chemical released by a cell in one part of the body, that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. It is essentially a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones; and a neurotransmitter Neurotransmitters are endogenous chemicals which transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side.[2]
As a stress hormone Stress hormones such as cortisol, GH and norepinephrine are released at periods of high stress. The hormone regulating system is known as the endocrine system. Cortisol is believed to affect the metabolic system and norepinephrine is believed to play a role in ADHD as well as depression and hypertension, norepinephrine affects parts of the brain where attention Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things. Attention has also been referred to as the allocation of processing resources and responding actions are controlled. Along with epinephrine Epinephrine is a hormone and neurotransmitter.. It increases heart rate, contracts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. Chemically, epinephrine is a catecholamine, a monoamine produced only by the adrenal glands from the amino acids phenylalanine and tyrosine, norepinephrine also underlies the fight-or-flight response The "fight-or-flight response", also called the "fight-or-flight-or-freeze response", the "fright, fight or flight response", "hyperarousal" or the "acute stress response", was first described by Walter Cannon in 1929, directly increasing heart rate Heart rate is the number of heartbeats per unit of time - typically expressed as beats per minute - which can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep. The measurement of heart rate is used by medical professionals to assist in the diagnosis and tracking of medical conditions. It, triggering the release of glucose Glucose , a simple sugar (monosaccharide), is an important carbohydrate in biology. Cells use it as a source of energy and a metabolic intermediate. Glucose is one of the main products of photosynthesis and starts cellular respiration. Starch and cellulose are polymers derived from the dehydration of glucose. The name "glucose" comes from energy stores, and increasing blood flow to skeletal muscle Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system. It is one of three major muscle types, the others being cardiac and smooth muscle. As its name suggests, most skeletal muscle is attached to bones by bundles of collagen fibers known as tendons. Norepinephrine can also suppress neuroinflammation Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process. Inflammation is not a synonym for infection. Even in cases where inflammation is when released diffusely in the brain from the locus ceruleus The Locus coeruleus, also spelled locus caeruleus, is a nucleus in the brain stem involved with physiological responses to stress and panic. It was discovered in the 1700s by Félix Vicq-d'Azyr.[3]
When norepinephrine acts as a drug A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage it increases blood pressure Blood pressure is a force exerted by circulating blood on the walls of blood vessels, and is one of the principal vital signs. During each heartbeat, BP varies between a maximum (systolic) and a minimum (diastolic) pressure. The mean BP, due to pumping by the heart and resistance in blood vessels, decreases as the circulating blood moves away from by increasing vascular tone through α-adrenergic receptor The adrenergic receptors are a class of G protein-coupled receptors that are targets of the catecholamines, especially noradrenaline (norepinephrine) and adrenaline (epinephrine). Although dopamine is a catecholamine, its receptors are in a different category activation. The resulting increase in vascular resistance triggers a compensatory reflex A reflex action, also known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. In most contexts, in particular those involving humans, reflex actions are mediated via the reflex arc; this is not always true in other animals, nor does it apply to casual uses of the term 'reflex' that overcomes its direct stimulatory effects on the heart, called the baroreceptor reflex In cardiovascular physiology, the baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms for maintaining blood pressure. It provides a negative feedback loop in which an elevated blood pressure reflexively causes blood pressure to decrease; similarly, decreased blood pressure depresses the baroreflex, causing blood pressure, which results in a drop in heart rate called reflex bradycardia Reflex bradychardia is a bradycardia in response to the baroreceptor reflex, one of the body's homeostatic mechanisms for preventing abnormal increases blood pressure. In the presence of high mean arterial pressure, the baroreceptor reflex produces a reflex bradycardia as a method of decreasing blood pressure by decreasing cardiac output.
Norepinephrine is synthesized from dopamine Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this phenethylamine functions as a neurotransmitter, activating the five types of dopamine receptors—D1, D2, D3, D4, and D5—and their variants. Dopamine is produced in several areas of the brain, by dopamine β-hydroxylase Dopamine β-hydroxylase is an enzyme that converts dopamine to norepinephrine.[4] It is released from the adrenal medulla The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the inner most part of the adrenal gland, consisting of cells that secrete epinephrine, norepinephrine, and a small amount of dopamine in response to stimulation by sympathetic preganglionic neurons into the blood as a hormone A hormone is a chemical released by a cell in one part of the body, that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. It is essentially a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones;, and is also a neurotransmitter Neurotransmitters are endogenous chemicals which transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side in the central nervous system The central nervous system is the part of the nervous system that coordinates the activity of all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish. It contains the majority of the nervous system and consists of the brain and the spinal cord, as well as and sympathetic nervous system The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's resources under stress; to induce the flight-or-fight response. It is, however, constantly active at a basal level in order to maintain homeostasis where it is released from noradrenergic neurons A neuron (pronounced /ˈnjʊərɒn/ NOOR-on, also known as a neurone or nerve cell) is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core. The actions of norepinephrine are carried out via the binding to adrenergic receptors The adrenergic receptors are a class of G protein-coupled receptors that are targets of the catecholamines, especially noradrenaline (norepinephrine) and adrenaline (epinephrine). Although dopamine is a catecholamine, its receptors are in a different category.
Contents |
Etymology
The term "norepinephrine" is derived from the chemical prefix nor- In chemistry, nor- is a prefix that means "next lower homolog". Specifically, it refers to compounds in which one or two methyl groups are removed from the parent compound and replaced with hydrogen atoms, or in which a methylene group has been removed from a chain in the parent compound, which indicates that norepinephrine is the next lower homolog A homolog in chemistry refers to a chemical compound from a series of compounds that differ only in the number of repeated structural units. A homolog is a special case of an analog. Examples are alkanes and compounds with alkyl functional groups that differ in the length of their sidechain or a peptide with one amino acid replaced by another of epinephrine Epinephrine is a hormone and neurotransmitter.. It increases heart rate, contracts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. Chemically, epinephrine is a catecholamine, a monoamine produced only by the adrenal glands from the amino acids phenylalanine and tyrosine. The two structures differ only in that epinephrine has a methyl group attached to its nitrogen, while the methyl group is replaced by a hydrogen atom in norepinephrine.
Chemistry
Norepinephrine is a catecholamine Catecholamines are sympathomimetic "fight-or-flight" hormones released by the adrenal glands in response to stress. They are part of the sympathetic nervous system and a phenethylamine Phenethylamine is a natural monoamine alkaloid, trace amine, and psychoactive drug with stimulant effects. In the mammalian central nervous system, phenethylamine is believed to function as a neuromodulator or neurotransmitter. It is biosynthesized from the amino acid phenylalanine by enzymatic decarboxylation. Besides mammals, phenethylamine is. The natural stereoisomer Stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms , but which differ only in the three-dimensional orientations of their atoms in space. Structural isomers share the same molecular formula, but the bond connections and/or their order between different atoms/groups differs. In stereoisomers, the is L-(−)-(R)-norepinephrine. The prefix nor- In chemistry, nor- is a prefix that means "next lower homolog". Specifically, it refers to compounds in which one or two methyl groups are removed from the parent compound and replaced with hydrogen atoms, or in which a methylene group has been removed from a chain in the parent compound, is derived from the German abbreviation for "N ohne Radikal" (N, the symbol for nitrogen, without radical In chemistry, radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Radicals may have positive, negative or zero charge. By convention, metals and their ions or complexes with unpaired electrons are not radicals. The unpaired electrons cause radicals to be highly chemically reactive),[5] referring to the absence of the methyl In chemistry, a methyl group is a hydrophobic alkyl functional group named after methylene (RC functional group In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of. However, its relative reactivity can be at the nitrogen atom.
Origins
Norepinephrine is released when a host of physiological Physiology is the science of the functioning of living systems. It is a subcategory of biology. In physiology, the scientific method is applied to determine how organisms, organ systems, organs, cells and biomolecules carry out the chemical or physical function that they have in a living system. The word physiology is from Ancient Greek: φύσις changes are activated by a stressful event.
In the brain, this is caused in part by activation of an area of the brain stem In vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Though small, this is an extremely important part of the brain as the nerve connections of the motor and called the locus ceruleus The Locus coeruleus, also spelled locus caeruleus, is a nucleus in the brain stem involved with physiological responses to stress and panic. It was discovered in the 1700s by Félix Vicq-d'Azyr. This nucleus is the origin of most norepinephrine pathways in the brain. Noradrenergic neurons project bilaterally (send signals to both sides of the brain) from the locus ceruleus along distinct pathways to many locations, including the cerebral cortex The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different composition in terms of neurons and connectivity. The human, limbic system The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, and limbic cortex, which suggestively support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin limbus, for "border" or "edge". Some, and the spinal cord The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system. The spinal cord extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column. It is around 4, forming a neurotransmitter system In neuroscience, neuromodulation is the process in which several classes of neurotransmitters in the nervous system regulate diverse populations of neurons . As opposed to direct synaptic transmission, in which one presynaptic neuron directly influences a postsynaptic partner (one neuron reaching one other neuron), neuromodulatory transmitters.
Norepinephrine is also released from postganglionic neurons In the autonomic nervous system, fibers from the ganglion to the effector organ are called postganglionic fibers of the sympathetic nervous system The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's resources under stress; to induce the flight-or-fight response. It is, however, constantly active at a basal level in order to maintain homeostasis, to transmit the fight-or-flight response in each tissue respectively. The adrenal medulla The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the inner most part of the adrenal gland, consisting of cells that secrete epinephrine, norepinephrine, and a small amount of dopamine in response to stimulation by sympathetic preganglionic neurons can also be counted to such postganglionic nerve cells, although they release norepinephrine into the blood.
Norepinephrine system
The noradrenergic neurons in the brain form a neurotransmitter system In neuroscience, neuromodulation is the process in which several classes of neurotransmitters in the nervous system regulate diverse populations of neurons . As opposed to direct synaptic transmission, in which one presynaptic neuron directly influences a postsynaptic partner (one neuron reaching one other neuron), neuromodulatory transmitters, that, when activated, exerts effects on large areas of the brain. The effects are alertness and arousal, and influences on the reward system.
Anatomically, the noradrenergic neurons originate both in the locus coeruleus and the lateral tegmental field. The axons of the neurons in the locus coeruleus act on adrenergic receptors in:
On the other hand, axons of neurons of the lateral tegmental field act on adrenergic receptors in hypothalamus, for example.
This structure explains some of the clinical uses of norepinephrine, since a modification of the system affects large areas of the brain.
Mechanism
Norepinephrine is synthesized from tyrosine as a precursor, and packed into synaptic vesicles. It performs its action by being released into the synaptic cleft, where it acts on adrenergic receptors, followed by the signal termination, either by degradation of norepinephrine, or by uptake by surrounding cells.
Biosynthesis
Norepinephrine is synthesized by a series of enzymatic steps in the adrenal medulla and postganglionic neurons of the sympathetic nervous system from the amino acid tyrosine:
- The first reaction is the hydroxylation into dihydroxyphenylalanine (L-DOPA) (DOPA = 3,4-DiHydroxy-L-Phenylalanine), catalyzed by tyrosine hydroxylase. This is the rate-limiting step.
- This is followed by decarboxylation into the neurotransmitter dopamine, catalyzed by pyridoxal phosphate & DOPA decarboxylase.
- Last is the final β-oxidation into norepinephrine by dopamine beta hydroxylase, requiring ascorbate as a cofactor (electron donor).
|
Norepinephrine |
Vesicular transport
Between the decarboxylation and the final β-oxidation, norepinephrine is transported into synaptic vesicles. This is accomplished by vesicular monoamine transporter (VMAT) in the lipid bilayer. This transporter has equal affinity for norepinephrine, epinephrine and isoprenaline.[6]
Release
To perform its functions, norepinephrine needs to be released from synaptic vesicles. Many substances modulate this release, some inhibiting it and some stimulating it.
For instance, there are inhibitory α2 adrenergic receptors presynaptically, that gives negative feedback on release by homotropic modulation.
Receptor binding
Main article: Adrenergic receptorNorepinephrine performs its actions on the target cell by binding to and activating adrenergic receptors. The target cell expression of different types of receptors determines the ultimate cellular effect, and thus norepinephrine has different actions on different cell types.
|
YourTango
Excitement and unpredictability create a spike in the brain's natural amphetamines dopamine and norepinephrine which in turn intensifies arousal levels. ...
488px x 618px | 72.00kB
[source page]
with no tolerance issues The results of the study suggest that milnacipran may have potential to relieve pain as well as other symptoms associated with fibromyalgia Vitton 2004 Table 1 Studies of serotonin norepinephrine reuptake inhibitors for treatment of fibromyalgia Discussion and Conclusion
Kee-In Lee, Se Hun Kwak and Jung Min Seo
Sat, 24 Jul 2010 04:00:00 GM
synaptosomes two times more potently than (R)-enantiomer.3 The (S)-duloxetine, a dual inhibitor of both serotonin and . norepinephrine. reuptake, is effective for the treatment of major depressive ...
Q. I've been curious as to whether or not nasal decongestants, pseudoephedrine HCL, have any effects on serotonin and norepinephrine levels in the brain. I know the usual side effects I experience when taking non-drowsy medication with 120 mg of pseudoephedrine HCL as the active ingredient are: drowsiness (when sleeping I experience night sweats as a result) followed by restlessness (inability to fall back to sleep after being drowsy from medication) and occasional anxiety levels (increased heart rate) as well as lightheadedness. I do not take an anti-depressants and I wont discuss my diet or exercise levels as I am not asking for diagnosis. I was just curious about the general effects on these products and specific chemicals in the brain.… [cont.]
Asked by Sper - Sat Jun 16 03:57:55 2007 - - 3 Answers - 0 Comments
A. Hi. I dont know about the serotonin, but I do about the others. Pseudoephedrine induces vesicles in the presynaptic cleft of adrenergic synapse's to release their noradrenaline (=norepinephrine) onto the post synaptic cleft, and thus induces a sympathetic response. This is why its used, it makes the vessels in the sinus and nose constrict, reducing the amount of fluid being produced, and clearing a runny nose. It also, therefore will cause some effect in the CNS (although it is more selctive for mucosa vessels than for the CNS), and will stimulate the increased anxiety and increased heart rate you mentioned. Wikipedia has lots of info on it: Hope this helps Ashley
Answered by Ashley - Sat Jun 16 08:55:26 2007
