Clinical data | |
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Trade names | Epirenor, Norden, Norfen |
Other names | OCT, Norsympathol, Norsynephrine, para-Octopamine, beta-Hydroxytyramine, 4,β-dihydroxyphenethylamine, para-hydroxy-phenyl-ethanolamine, α-(Aminomethyl)-4 hydroxybenzenemethanol, 1-(p-Hydroxyphenyl)-2-aminoethanol |
Routes of administration | Oral |
ATC code | |
Physiological data | |
Source tissues | Invertebrate nervous systems; trace amine in vertebrates |
Target tissues | System-wide in invertebrates |
Receptors | TAAR1 (mammals) OctαR, OctβR, TyrR (invertebrates), Oct-TyrR |
Agonists | Formamidines (amitraz (AMZ) and chlordimeform (CDM)) |
Antagonists | Epinastine |
Precursor | Tyramine |
Biosynthesis | Tyramine β-hydroxylase; dopamine β-hydroxylase |
Metabolism | p-Hydroxymandelic acid; [1] [2] N-acetyltransferases; phenylethanolamine N-methyltransferase |
Legal status | |
Legal status |
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Pharmacokinetic data | |
Bioavailability | 99.42% |
Metabolism | p-Hydroxymandelic acid; [1] [4] N-acetyltransferases; phenylethanolamine N-methyltransferase |
Elimination half-life | 15 minutes in insects. Between 76 and 175 minutes in humans |
Excretion | Up to 93% of ingested octopamine is eliminated via the urinary route within 24 hours [1] |
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CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.002.890 |
Chemical and physical data | |
Formula | C8H11NO2 |
Molar mass | 153.181 g·mol−1 |
3D model (JSmol) | |
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Octopamine (OA), also known as para-octopamine and norsynephrine among synonyms, is an organic chemical closely related to norepinephrine, and synthesized biologically by a homologous pathway. Octopamine is often considered the major "fight-or-flight" neurohormone of invertebrates. Its name is derived from the fact that it was first identified in the salivary glands of the octopus.
In many types of invertebrates, octopamine is an important neurotransmitter and hormone. In protostomes—arthropods, molluscs, and several types of worms—it substitutes for norepinephrine and performs functions apparently similar to those of norepinephrine in mammals, functions that have been described as mobilizing the body and nervous system for action. In mammals, octopamine is found only in trace amounts (i.e., it is a trace amine), and no biological function has been solidly established for it. It is also found naturally in numerous plants, including bitter orange. [5] [6]
Octopamine has been sold under trade names such as Epirenor, Norden, and Norfen for use as a sympathomimetic drug, available by prescription.
Octopamine exerts its effects by binding to and activating receptors located on the surface of cells. These receptors have mainly been studied in insects, where they can be divided into distinct types:
Phylogenetic studies claim that in ancient bilaterians such as Platynereis dumerilii there is a co-existence of norepinephrine, tyramine and octopamine receptor signaling. However, due to partial overlapping in their signalling functionality tyramine and octopamine receptors have been lost in vertebrates. [11]
In vertebrates no octopamine-specific receptors have been identified. Octopamine binds weakly to receptors for norepinephrine and epinephrine, but it is not clear whether this has any functional significance. It binds more strongly to trace amine-associated receptors (TAARs), especially TAAR1. [10]
Octopamine was first discovered by Italian scientist Vittorio Erspamer in 1948 [12] in the salivary glands of the octopus and has since been found to act as a neurotransmitter, neurohormone and neuromodulator in invertebrates. Although Erspamer discovered its natural occurrence and named it, octopamine had actually existed for many years as a pharmaceutical product. [13] It is widely used in energy-demanding behaviors by all insects, crustaceans (crabs, lobsters, crayfish), and spiders. Such behaviors include modulating muscle tension, [14] flying, [15] ovulation and egg-laying, [16] [17] [18] [19] [20] [21] and jumping. [22] [23]
In lobsters, octopamine seems to direct and coordinate neurohormones to some extent in the central nervous system, and it was observed that injecting octopamine into a lobster and crayfish resulted in limb and abdomen extension. [24]
In the nematode, octopamine is found in high concentrations in adults, decreasing egg-laying and pharyngeal pumping behaviors with an antagonistic effect to serotonin. [25]
Octopaminergic nerves in the mollusc may be present in the heart, with high concentrations in the nervous system. [26]
In insects, octopamine is released by a select number of neurons, but acts broadly throughout the central brain, on all sense organs, and on several non-neuronal tissues. [27] [28] In the thoracic ganglia, octopamine is primarily released by DUM (dorsal unpaired median) and VUM (ventral unpaired median) neurons, which release octopamine onto neural, muscular, and peripheral targets. [29] [30] These neurons are important for mediating energy-demanding motor behaviors, such as escape-induced jumping and flight. For example, the locust DUMeti neuron releases octopamine onto the extensor tibia muscle to increase muscle tension and increase relaxation rate. These actions promote efficient leg muscle contraction for jumping. [27] During flight, DUM neurons are also active and release octopamine throughout the body to synchronize energy metabolism, respiration, muscle activity and flight interneuron activity. [15] Octopamine in locusts is four times more concentrated in the axon than in the soma, and decreases the locust's myogenic rhythm. [31]
In the honey bee, octopamine has a major role in learning and memory. In the firefly, octopamine release leads to light production in the lantern. [32] [33]
In larvae of the oriental armyworm, octopamine is immunologically beneficial, increasing survival rates in high-density populations. [34]
The emerald cockroach wasp stings the host for its larvae (a cockroach) in the head ganglion (brain). The venom blocks octopamine receptors [35] and the cockroach fails to show normal escape responses, grooming itself excessively. It becomes docile and the wasp leads it to the wasp's den by pulling its antenna like a leash. [36]
Octopamine affects almost every process of the fruit fly and is widely present in both the adult and larval fly. A non-exhaustive list of some of the areas in which Octopamine modulates:
In vertebrates, octopamine replaces norepinephrine in sympathetic neurons with chronic use of monoamine oxidase inhibitors. It may be responsible for the common side effect of orthostatic hypotension with these agents, though there is also evidence that it is actually mediated by increased levels of N-acetylserotonin.
One study noted that octopamine might be an important amine that influences the therapeutic effects of inhibitors such as monoamine oxidase inhibitors, especially because a large increase in octopamine levels was observed when animals were treated with this inhibitor. Octopamine was positively identified in the urine samples of mammals such as humans, rats, and rabbits treated with monoamine oxidase inhibitors. Very small amounts of octopamine were also found in certain animal tissues. It was observed that within a rabbit's body, the heart and kidney held the highest concentrations of octopamine. Octopamine was found to be 93% eluted by urine within 24 hours of being produced in the body as a byproduct of Iproniazid in rabbits. [13]
Octopamine has been sold under trade names such as Epirenor, Norden, and Norfen for use in medicine as a sympathomimetic drug, available by prescription. However, very little information exists concerning its clinical usefulness or safety. [61] It has been studied as an antihypotensive agent and has been shown to increase blood pressure when administered intravenously, intramuscularly, and buccally at sufficiently high doses, whereas oral administration was ineffective. [61]
Octopamine is an analogue of sympathomimetic catecholamines like norepinephrine and phenethylamines like tyramine. [61] However, octopamine has 400- to 2,000-fold lower affinity for the mammalian α- and β-adrenergic receptors than norepinephrine. [61] In any case, it can produce significant sympathomimetic effects, like pressor responses, at sufficiently high doses. [61]
In mammals, octopamine may mobilize the release of fat from adipocytes (fat cells), which has led to its promotion on the internet as a slimming aid. However, the released fat is likely to be promptly taken up into other cells, and there is no evidence that octopamine facilitates weight loss. Octopamine may also increase blood pressure significantly when combined with other stimulants, as in some weight loss supplements. [62]
The World Anti-Doping Agency lists octopamine as a banned substance for in competition use, as a "specified stimulant" [63] on the 2019 Prohibited List.
The octopamine receptor is a target of insecticides, as its blockage leads to decreased cyclic adenosine monophosphate (cAMP) levels. Essential oils can have such a neuro-insecticidal effect, [64] and this octopamine-receptor mechanism is naturally utilized by plants with active insecticidal phytochemicals. [65]
Octopamine is one of four primary endogenous agonists of human trace amine-associated receptor 1 together with 3-iodothyronamine, dopamine and tyramine. [66] [67]
Octopamine binds to its respective G-protein coupled receptors (GPCRs) to initiate a cell signal transduction pathway. At least three groups of octopamine GPCR have been defined. OctαR (OCTOPAMINE1 receptors) are more closely related to α-adrenergic receptors, while OctβR (OCTOPAMINE2 receptors) are more closely related to β-adrenergic receptors. The Octopamine/Tyramine receptors (including Oct-TyrR) can bind both ligands, and display agonist-specific coupling. Oct-TyrR is listed in both OCTOPAMINE and TYRAMINE RECEPTORS gene groups. [68]
Octopamine acts as the insect equivalent of norepinephrine and has been implicated in regulating aggression in invertebrates, with different effects on different species. Studies have shown that reducing the neurotransmitter octopamine and preventing coding of tyramine β-hydroxylase (an enzyme that converts tyramine to octopamine) decreases aggression in Drosophila without influencing other behaviors. [69]
Octopamine, or para-octopamine, also known as 4,β-dihydroxyphenethylamine, is a substituted phenethylamine derivative. It is related to analogues including phenylethanolamine (β-hydroxyphenethylamine), tyramine (para-tyramine; 4-hydroxyphenethylamine), and norfenefrine (meta-octopamine; 3,β-dihydroxyphenethylamine), among others.
Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex, touching on diverse functions including mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction.
Drosophila melanogaster is a species of fly in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly", or "banana fly". In the wild, D. melanogaster are attracted to rotting fruit and fermenting beverages, and are often found in orchards, kitchens and pubs.
The mushroom bodies or corpora pedunculata are a pair of structures in the brain of arthropods, including insects and crustaceans, and some annelids. They are known to play a role in olfactory learning and memory. In most insects, the mushroom bodies and the lateral horn are the two higher brain regions that receive olfactory information from the antennal lobe via projection neurons. They were first identified and described by French biologist Félix Dujardin in 1850.
Tyramine, also known under several other names, is a naturally occurring trace amine derived from the amino acid tyrosine. Tyramine acts as a catecholamine releasing agent. Notably, it is unable to cross the blood-brain barrier, resulting in only non-psychoactive peripheral sympathomimetic effects following ingestion. A hypertensive crisis can result, however, from ingestion of tyramine-rich foods in conjunction with the use of monoamine oxidase inhibitors (MAOIs).
Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the gut, muscles, and heart.
Transient receptor potential channels are a group of ion channels located mostly on the plasma membrane of numerous animal cell types. Most of these are grouped into two broad groups: Group 1 includes TRPC, TRPV, TRPVL, TRPM, TRPS, TRPN, and TRPA. Group 2 consists of TRPP and TRPML. Other less-well categorized TRP channels exist, including yeast channels and a number of Group 1 and Group 2 channels present in non-animals. Many of these channels mediate a variety of sensations such as pain, temperature, different kinds of taste, pressure, and vision. In the body, some TRP channels are thought to behave like microscopic thermometers and used in animals to sense hot or cold. Some TRP channels are activated by molecules found in spices like garlic (allicin), chili pepper (capsaicin), wasabi ; others are activated by menthol, camphor, peppermint, and cooling agents; yet others are activated by molecules found in cannabis or stevia. Some act as sensors of osmotic pressure, volume, stretch, and vibration. Most of the channels are activated or inhibited by signaling lipids and contribute to a family of lipid-gated ion channels.
Campaniform sensilla are a class of mechanoreceptors found in insects, which respond to local stress and strain within the animal's cuticle. Campaniform sensilla function as proprioceptors that detect mechanical load as resistance to muscle contraction, similar to mammalian Golgi tendon organs. Sensory feedback from campaniform sensilla is integrated in the control of posture and locomotion.
Chordotonal organs are stretch receptor organs found only in insects and crustaceans. They are located at most joints and are made up of clusters of scolopidia that either directly or indirectly connect two joints and sense their movements relative to one another. They can have both extero- and proprioceptive functions, for example sensing auditory stimuli or leg movement. The word was coined by Vitus Graber in 1882, though he interpreted them as being stretched between two points like a string, sensing vibrations through resonance.
Odorant-binding proteins (OBPs) are small soluble proteins secreted by auxiliary cells surrounding olfactory receptor neurons, including the nasal mucus of many vertebrate species and in the sensillar lymph of chemosensory sensilla of insects. OBPs are characterized by a specific protein domain that comprises six α-helices joined by three disulfide bonds. Although the function of the OBPs as a whole is not well established, it is believed that they act as odorant transporters, delivering the odorant molecules to olfactory receptors in the cell membrane of sensory neurons.
Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as a hormone, neurotransmitter and neuromodulator. The name "noradrenaline" is more commonly used in the United Kingdom, whereas "norepinephrine" is usually preferred in the United States. "Norepinephrine" is also the international nonproprietary name given to the drug. 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.
Norfenefrine, also known as meta-octopamine or norphenylephrine and sold under the brand name Novadral among others, is a sympathomimetic medication which is used in the treatment of hypotension. Along with its structural isomer p-octopamine and the tyramines, norfenefrine is a naturally occurring endogenous trace amine and plays a role as a minor neurotransmitter in the brain.
Trace amine-associated receptor 1 (TAAR1) is a trace amine-associated receptor (TAAR) protein that in humans is encoded by the TAAR1 gene. TAAR1 is an intracellular amine-activated Gs-coupled and Gq-coupled G protein-coupled receptor (GPCR) that is primarily expressed in several peripheral organs and cells, astrocytes, and in the intracellular milieu within the presynaptic plasma membrane of monoamine neurons in the central nervous system (CNS). TAAR1 was discovered in 2001 by two independent groups of investigators, Borowski et al. and Bunzow et al. TAAR1 is one of six functional human trace amine-associated receptors, which are so named for their ability to bind endogenous amines that occur in tissues at trace concentrations. TAAR1 plays a significant role in regulating neurotransmission in dopamine, norepinephrine, and serotonin neurons in the CNS; it also affects immune system and neuroimmune system function through different mechanisms.
Crustacean cardioactive peptide (CCAP) is a highly conserved, amidated cyclic nonapeptide with the primary structure PFCNAFTGC-NH2 (ProPheCysAsnAlaPheTyrGlyCys-NH2) and a disulfide bridge between Cys3 and Cys9. It is found in crustaceans and insects where it behaves as a cardioaccelerator, neuropeptide transmitter for other areas of the nervous system and a hormone. CCAP was first isolated from the pericardial organs of the shore crab Carcinus maenas, where it has a role in regulating heartbeat. It was assumed that this was the peptide's main function and its name reflects this.
Corazonin is a highly conserved neuropeptide found in many insects, in particular locusts and cockroaches.
Bursicon is an insect hormone which mediates tanning in the cuticle of adult flies. This hormone was identified by Gottfried S. Fraenkel with his student Catherine Hsiao in 1965.
Pigment dispersing factor (pdf) is a gene that encodes the protein PDF, which is part of a large family of neuropeptides. Its hormonal product, pigment dispersing hormone (PDH), was named for the diurnal pigment movement effect it has in crustacean retinal cells upon its initial discovery in the central nervous system of arthropods. The movement and aggregation of pigments in retina cells and extra-retinal cells is hypothesized to be under a split hormonal control mechanism. One hormonal set is responsible for concentrating chromatophoral pigment by responding to changes in the organism's exposure time to darkness. Another hormonal set is responsible for dispersion and responds to the light cycle. However, insect pdf genes do not function in such pigment migration since they lack the chromatophore.
Hair plates are a type of proprioceptor found in the folds of insect joints. They consist of a cluster of hairs, in which each hair is innervated by a single mechanosensory neuron. Functionally, hair plates operate as "limit-detectors" by signaling the extremes of joint movement, which then drives reflexive leg movement.
Nilay Yapici is a Turkish neuroscientist at Cornell University in Ithaca, New York, where she is the Nancy and Peter Meinig Family Investigator in the Life Sciences and Adelson Sesquicentennial Fellow in the Department of Neurobiology and Behavior. Yapici studies the neural circuits underlying decision making and feeding behavior in fruit fly models.
Reinhard F. Stocker is a Swiss biologist. He pioneered the analysis of the sense of smell and taste in higher animals, using the fly Drosophila melanogaster as a study case. He provided a detailed account of the anatomy and development of the olfactory system, in particular across metamorphosis, for which he received the Théodore-Ott-Prize of the Swiss Academy of Medical Sciences in 2007, and pioneered the use of larval Drosophila for the brain and behavioural sciences.
A descending neuron is a neuron that conveys signals from the brain to neural circuits in the spinal cord (vertebrates) or ventral nerve cord (invertebrates). As the sole conduits of information between the brain and the body, descending neurons play a key role in behavior. Their activity can initiate, maintain, modulate, and terminate behaviors such as locomotion. Because the number of descending neurons is several orders of magnitude smaller than the number of neurons in either the brain or spinal cord/ventral nerve cord, this class of cells represents a critical bottleneck in the flow of information from sensory systems to motor circuits.