# Catecholamine

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Class of chemical compounds

Catecholamines

[Epinephrine](/source/Epinephrine) (adrenaline)

[Norepinephrine](/source/Norepinephrine) (noradrenaline)

[Dopamine](/source/Dopamine)

[Catechol](/source/Catechol)

A **catecholamine** ([/ˌkætəˈkoʊləmiːn/](https://en.wikipedia.org/wiki/Help:IPA/English); abbreviated **CA**), most typically a **3,4-dihydroxyphenethylamine**, is a [monoamine neurotransmitter](/source/Monoamine_neurotransmitter), an [organic compound](/source/Organic_compound) that has a [catechol](/source/Catechol) ([benzene](/source/Benzene) with two [hydroxyl](/source/Hydroxyl) side groups next to each other) and a [side-chain](/source/Side_chain) [amine](/source/Amine).[1]

[Catechol](/source/Catechol) can be either a free molecule or a [substituent](/source/Substituent) of a larger molecule, where it represents a 1,2-dihydroxybenzene group.

Catecholamines are derived from the [amino acid](/source/Amino_acid) [tyrosine](/source/Tyrosine), which is derived from dietary sources as well as synthesis from [phenylalanine](/source/Phenylalanine).[2] Catecholamines are water-soluble and are 50% bound to plasma proteins in circulation.

Included among catecholamines are [epinephrine](/source/Epinephrine) (adrenaline), [norepinephrine](/source/Norepinephrine) (noradrenaline), and [dopamine](/source/Dopamine). Release of the [hormones](/source/Hormone) epinephrine and norepinephrine from the [adrenal medulla](/source/Adrenal_medulla) of the [adrenal glands](/source/Adrenal_gland) is part of the [fight-or-flight response](/source/Fight-or-flight_response).[3]

Tyrosine is created from phenylalanine by [hydroxylation](/source/Hydroxylation) by the enzyme [phenylalanine hydroxylase](/source/Phenylalanine_hydroxylase). Tyrosine is also ingested directly from dietary protein. Catecholamine-secreting cells use several reactions to convert tyrosine serially to [L-DOPA](/source/L-DOPA) and then to dopamine. Depending on the cell type, dopamine may be further converted to norepinephrine or even further converted to epinephrine.[4]

Various [stimulant](/source/Stimulant) drugs (such as a number of [substituted amphetamines](/source/Substituted_amphetamine)) are catecholamine analogues.

## Structure

Catecholamines have the distinct structure of a [benzene ring](/source/Benzene_ring) with two [hydroxyl](/source/Hydroxyl) groups, an intermediate [ethyl](/source/Ethyl_group) chain, and a terminal [amine](/source/Amine) group. Phenylethanolamines such as norepinephrine have a hydroxyl group on the ethyl chain.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

## Production and degradation

Biosynthetic pathways for catecholamines and trace amines in the human brain[5][6][7] L-Phenylalanine L-Tyrosine L-DOPA Epinephrine Phenethylamine p-Tyramine Dopamine Norepinephrine N-Methylphenethylamine N-Methyltyramine p-Octopamine Synephrine 3-Methoxytyramine AADC AADC AADC primary pathway PNMT PNMT PNMT PNMT AAAH AAAH brain CYP2D6 minor pathway COMT DBH DBH In humans, catecholamines (shown in yellow) are derived from the amino acid L-phenylalanine. L-Phenylalanine is converted into L-tyrosine by an aromatic amino acid hydroxylase (AAAH) enzyme (phenylalanine 4-hydroxylase), with molecular oxygen (O2) and tetrahydrobiopterin as cofactors. L-Tyrosine is converted into L-DOPA by another AAAH enzyme (tyrosine 3-hydroxylase) with tetrahydrobiopterin, O2, and ferrous iron (Fe2+) as cofactors. L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase (AADC), with pyridoxal phosphate as the cofactor. Dopamine itself is also used as precursor in the synthesis of the neurotransmitters norepinephrine and epinephrine. Dopamine is converted into norepinephrine by the enzyme dopamine β-hydroxylase (DBH), with O2 and L-ascorbic acid as cofactors. Norepinephrine is converted into epinephrine by the enzyme phenylethanolamine N-methyltransferase (PNMT) with S-adenosyl-L-methionine as the cofactor.

### Location

Catecholamines are produced mainly by the [chromaffin cells](/source/Chromaffin_cells) of the [adrenal medulla](/source/Adrenal_medulla) and the [postganglionic fibers](/source/Postganglionic_fiber) of the [sympathetic nervous system](/source/Sympathetic_nervous_system). [Dopamine](/source/Dopamine), which acts as a [neurotransmitter](/source/Neurotransmitter) in the [central nervous system](/source/Central_nervous_system), is largely produced in neuronal cell bodies in two areas of the brainstem: the [ventral tegmental area](/source/Ventral_tegmental_area) and the [substantia nigra](/source/Substantia_nigra), the latter of which contains [neuromelanin](/source/Neuromelanin)-pigmented neurons. The similarly neuromelanin-pigmented cell bodies of the [locus coeruleus](/source/Locus_coeruleus) produce [norepinephrine](/source/Norepinephrine). [Epinephrine](/source/Epinephrine) is produced in small groups of neurons in the human brain which express its synthesizing enzyme, [phenylethanolamine *N*-methyltransferase](/source/Phenylethanolamine_N-methyltransferase);[8] these neurons project from a nucleus that is adjacent (ventrolateral) to the [area postrema](/source/Area_postrema) and from a nucleus in the dorsal region of the [solitary tract](/source/Solitary_tract).[8]

### Biosynthesis

Dopamine is the first catecholamine synthesized from DOPA. In turn, norepinephrine and epinephrine are derived from further metabolic modification of dopamine. The enzyme dopamine hydroxylase requires copper as a [cofactor](/source/Cofactor_(biochemistry)) (not shown in the diagram) and DOPA decarboxylase requires [PLP](/source/Pyridoxal_phosphate) (not shown in the diagram). The rate limiting step in catecholamine biosynthesis through the predominant metabolic pathway is the hydroxylation of L-tyrosine to L-DOPA.[9]

Catecholamine synthesis is inhibited by alpha-methyl-*p*-tyrosine ([AMPT](/source/AMPT)), which inhibits [tyrosine hydroxylase](/source/Tyrosine_hydroxylase).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

The amino acids [phenylalanine](/source/Phenylalanine) and [tyrosine](/source/Tyrosine) are precursors for catecholamines. Both amino acids are found in high concentrations in [blood plasma](/source/Blood_plasma) and the brain. In mammals, tyrosine can be formed from dietary phenylalanine by the enzyme [phenylalanine hydroxylase](/source/Phenylalanine_hydroxylase), found in large amounts in the liver. Insufficient amounts of phenylalanine hydroxylase result in [phenylketonuria](/source/Phenylketonuria), a metabolic disorder that leads to intellectual deficits unless treated by dietary manipulation.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] Catecholamine synthesis is usually considered to begin with tyrosine. The enzyme [tyrosine hydroxylase](/source/Tyrosine_hydroxylase) (TH) converts the amino acid L-tyrosine into 3,4-dihydroxyphenylalanine (L-DOPA). The hydroxylation of L-tyrosine by TH results in the formation of the DA precursor L-DOPA, which is metabolized by [aromatic L-amino acid decarboxylase](/source/Aromatic_L-amino_acid_decarboxylase) (AADC; see Cooper et al., 2002[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]) to the transmitter dopamine. This step occurs so rapidly that it is difficult to measure L-DOPA in the brain without first inhibiting AADC.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] In [neurons](/source/Neuron) that use DA as the transmitter, the decarboxylation of L-DOPA to dopamine is the final step in formation of the transmitter; however, in those neurons using [norepinephrine](/source/Norepinephrine) (noradrenaline) or [epinephrine](/source/Epinephrine) (adrenaline) as transmitters, the enzyme [dopamine β-hydroxylase](/source/Dopamine_beta-hydroxylase) (DBH), which converts dopamine to yield norepinephrine, is also present. In still other neurons in which epinephrine is the transmitter, a third enzyme [phenylethanolamine *N*-methyltransferase (PNMT)](/source/Phenylethanolamine_N-methyltransferase) converts norepinephrine into epinephrine. Thus, a cell that uses epinephrine as its transmitter contains four enzymes (TH, AADC, DBH, and PNMT), whereas norepinephrine neurons contain only three enzymes (lacking PNMT) and dopamine cells only two (TH and AADC).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

### Degradation

Catecholamines have a half-life of a few minutes when circulating in the blood. They can be degraded either by methylation by [catechol-*O*-methyltransferases (COMT)](/source/Catechol-O-methyl_transferase) or by deamination by [monoamine oxidases (MAO)](/source/Monoamine_oxidase).

[MAOIs](/source/MAOI) bind to MAO, thereby preventing it from breaking down catecholamines and other monoamines.

[Catabolism](/source/Catabolism) of catecholamines is mediated by two main enzymes: catechol-*O*-methyltransferase (COMT) which is present in the synaptic cleft and cytosol of the cell and monoamine oxidase (MAO) which is located in the mitochondrial membrane. Both enzymes require cofactors: COMT uses [Mg2+](/source/Magnesium_in_biology) as a cofactor while MAO uses [FAD](/source/Flavin_adenine_dinucleotide). The first step of the catabolic process is mediated by either MAO or COMT which depends on the tissue and location of catecholamines (for example degradation of catecholamines in the synaptic cleft is mediated by COMT because MAO is a mitochondrial enzyme). The next catabolic steps in the pathway involve [alcohol dehydrogenase](/source/Alcohol_dehydrogenase), [aldehyde dehydrogenase](/source/Aldehyde_dehydrogenase) and [aldehyde reductase](/source/Aldehyde_reductase). The end product of epinephrine and norepinephrine is [vanillylmandelic acid (VMA)](/source/Vanillylmandelic_acid) which is excreted in the [urine](/source/Urine). Dopamine catabolism leads to the production of [homovanillic acid (HVA)](/source/Homovanillic_acid).[10]

## Function

### Modality

Two catecholamines, [norepinephrine](/source/Norepinephrine) and [dopamine](/source/Dopamine), act as [neuromodulators](/source/Neuromodulators) in the [central nervous system](/source/Central_nervous_system) and as hormones in the blood circulation. The catecholamine [norepinephrine](/source/Norepinephrine) is a neuromodulator of the peripheral sympathetic nervous system but is also present in the blood (mostly through "spillover" from the [synapses](/source/Synapse) of the sympathetic system).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

High catecholamine levels in blood are associated with [stress](/source/Stress_(medicine)), which can be induced from psychological reactions or environmental stressors such as [elevated sound levels](/source/Noise_health_effects), [intense light](/source/Light_pollution), or [low blood sugar levels](/source/Hypoglycemia).[11]

Extremely high levels of catecholamines (also known as catecholamine toxicity) can occur in [central nervous system](/source/Central_nervous_system) trauma due to stimulation or damage of [nuclei](/source/Nucleus_(neuroanatomy)) in the [brainstem](/source/Brainstem), in particular, those nuclei affecting the [sympathetic nervous system](/source/Sympathetic_nervous_system). In [emergency medicine](/source/Emergency_medicine), this occurrence is widely known as a "catecholamine dump".

Extremely high levels of catecholamine can also be caused by [neuroendocrine tumors](/source/Neuroendocrine_tumor) in the [adrenal medulla](/source/Adrenal_medulla), a treatable condition known as [pheochromocytoma](/source/Pheochromocytoma).

High levels of catecholamines can also be caused by [monoamine oxidase A (MAO-A)](/source/Monoamine_oxidase_A) deficiency, known as [Brunner syndrome](/source/Brunner_syndrome). As MAO-A is one of the enzymes responsible for degradation of these neurotransmitters, its deficiency increases the [bioavailability](/source/Bioavailability) of these neurotransmitters considerably. It occurs in the absence of [pheochromocytoma](/source/Pheochromocytoma), [neuroendocrine tumors](/source/Neuroendocrine_tumor), and [carcinoid syndrome](/source/Carcinoid_syndrome), but it looks similar to carcinoid syndrome with symptoms such as facial flushing and aggression.[12][13]

Acute [porphyria](/source/Porphyria) can cause elevated catecholamines.[14]

## Aging

Degeneration of the [locus coeruleus](/source/Locus_coeruleus) and reduced production of norepinephrine during aging are under preliminary research as possible factors in the pathogenesis of [Alzheimer's disease](/source/Alzheimer's_disease).[15]

## Physiological effects

Catecholamines cause general physiological changes that prepare the body for physical activity (the [fight-or-flight response](/source/Fight-or-flight_response)). Some typical effects are increases in [heart rate](/source/Heart_rate), [blood pressure](/source/Blood_pressure), [blood glucose](/source/Blood_glucose) levels, and a general reaction of the [sympathetic nervous system](/source/Sympathetic_nervous_system).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] Some drugs, like [tolcapone](/source/Tolcapone) (a central [COMT](/source/COMT)-inhibitor), raise the levels of all the catecholamines. Increased catecholamines may also cause an increased respiratory rate ([tachypnoea](/source/Tachypnea)) in patients.[16]

Catecholamine is secreted into urine after being broken down, and its secretion level can be measured for the diagnosis of illnesses associated with catecholamine levels in the body.[17] [Urine testing](/source/Clinical_urine_tests) for catecholamine is used to detect [pheochromocytoma](/source/Pheochromocytoma).

### Function in plants

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They have been found in 44 plant families, but no essential metabolic function has been established for them. They are precursors of benzo[*c*]phenanthridine [alkaloids](/source/Alkaloid), which are the active principal ingredients of many [medicinal plant](/source/Medicinal_plant) extracts. CAs have been implicated to have a possible protective role against insect predators, injuries, and nitrogen detoxification. They have been shown to promote plant tissue growth, somatic [embryogenesis](/source/Embryogenesis) from in vitro cultures, and flowering. CAs inhibit [indole-3-acetic acid](/source/Indole-3-acetic_acid) oxidation and enhance [ethylene](/source/Ethylene) biosynthesis. They have also been shown to enhance synergistically various effects of [gibberellins](/source/Gibberellin).[18]

## Testing for catecholamines

Catecholamines are secreted by cells in tissues of different systems of the human body, mostly by the nervous and the endocrine systems. The adrenal glands secrete certain catecholamines into the blood when the person perceives a threat and prepares for a [fight-or-flight response](/source/Fight-or-flight_response).[19] However, acute or chronic excess of circulating catecholamines can potentially increase blood pressure and heart rate to very high levels and eventually provoke dangerous effects. Tests for fractionated plasma free [metanephrines](/source/Metanephrines) or the urine metanephrines are used to confirm or exclude certain diseases when the doctor identifies signs of [hypertension](/source/Hypertension) and [tachycardia](/source/Tachycardia) that don't adequately respond to treatment.[20][21] Each of the tests measure the amount of adrenaline and noradrenaline metabolites, respectively called [metanephrine](/source/Metanephrine) and [normetanephrine](/source/Normetanephrine).

Blood tests are also done to analyze the amount of catecholamines present in the body.

Catecholamine tests are done to identify rare tumors at the adrenal gland or in the nervous system. Catecholamine tests provide information relative to tumors such as: pheochromocytoma, paraganglioma, and neuroblastoma.[22][23]

## See also

- [Catechol-*O*-methyltransferase](/source/Catechol-O-methyltransferase)

- [Catecholaminergic polymorphic ventricular tachycardia](/source/Catecholaminergic_polymorphic_ventricular_tachycardia)

- [History of catecholamine research](/source/History_of_catecholamine_research)

- [Hormone](/source/Hormone)

- [Julius Axelrod](/source/Julius_Axelrod)

- [Peptide hormone](/source/Peptide_hormone)

- [Phenethylamine](/source/Phenethylamine)

- [Steroid hormone](/source/Steroid_hormone)

- [Sympathomimetic drug](/source/Sympathomimetic_drug)

- [Vanillylmandelic acid](/source/Vanillylmandelic_acid)

## References

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## External links

- [Catecholamines](https://meshb.nlm.nih.gov/record/ui?name=Catecholamines) at the U.S. National Library of Medicine [Medical Subject Headings](/source/Medical_Subject_Headings) (MeSH)

v t e Neurotransmitters Amino acid-derived Major excitatory / inhibitory systems Glutamate system Agmatine Aspartic acid (aspartate) Glutamic acid (glutamate) Glutathione Glycine GSNO GSSG Kynurenic acid NAA NAAG Proline Serine GABA system GABA GABOB GHB Glycine system α-Alanine β-Alanine Glycine Hypotaurine Proline Sarcosine Serine Taurine GHB system GHB T-HCA (GHC) Biogenic amines Monoamines 6-OHM Dopamine Epinephrine (adrenaline) NAS (normelatonin) Norepinephrine (noradrenaline) Serotonin (5-HT) Trace amines 3-Iodothyronamine N-Methylphenethylamine N-Methyltryptamine m-Octopamine p-Octopamine Phenylethanolamine Phenethylamine Synephrine Tryptamine m-Tyramine p-Tyramine Others Histamine Neuropeptides See here instead. Lipid-derived Endocannabinoids 2-AG 2-AGE (noladin ether) 2-ALPI 2-OG AA-5-HT Anandamide (AEA) DEA LPI NADA NAGly OEA Oleamide PEA RVD-Hpα SEA Virodhamine (O-AEA) Neurosteroids See here instead. Nucleobase-derived Nucleosides Adenosine system ADP AMP ATP Vitamin-derived Miscellaneous Cholinergic system Acetylcholine Gasotransmitters Carbon monoxide (CO) Hydrogen sulfide (H2S) Nitric oxide (NO) Candidates Acetaldehyde Ammonia (NH3) Carbonyl sulfide (COS) Nitrous oxide (N2O) Sulfur dioxide (SO2)

v t e Neurotransmitter metabolic intermediates Catecholamines Anabolism Phenylalanine → Tyrosine → DOPA (levodopa) → Dopamine → Norepinephrine → Epinephrine Catabolism Dopamine 3,4-Dihydroxyphenylacetaldehyde (DOPAL) 3,4-Dihydroxyphenylacetic acid (DOPAC) Homovanillyl alcohol Hydroxytyrosol (3,4-dihydroxyphenylethanol; DOPET) 3-Methoxytyramine (3-MT) Homovanillic acid (HVA) Norepinephrine 3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL, DHMAL) 3,4-Dihydroxymandelic acid (DHMA) Normetanephrine 3-Methoxy-4-hydroxymandelaldehyde (MHMAL) Vanillylmandelic acid (VMA) 3,4-Dihydroxyphenylethylene glycol (DOPEG, DHPG) 3-Methoxy-4-hydroxyphenylglycol (MHPG, MOPEG) Epinephrine 3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL, DHMAL) Metanephrine 3-Methoxy-4-hydroxymandelaldehyde (MHMAL) Tryptophan→Serotonin Anabolism Tryptophan 5-Hydroxytryptophan (5-HTP) Catabolism 5-Hydroxyindoleacetaldehyde (5-HIAL) 5-Hydroxyindoleacetic acid (5-HIAA) 5-Hydroxytryptophol (5-HTOL) Serotonin→Melatonin N-Acetylserotonin (NAS; normelatonin) 5-Methoxytryptamine (5-MT) 5-Methoxyindoleacetaldehyde (5-MIAL) Trace amines 3-Methoxy-4-hydroxyphenylacetaldehyde (HMPAL) 4-Hydroxyphenylacetaldehyde (HPAL) Indoleacetaldehyde (IAL) Phenacetaldehyde (PAL) Histamine Histidine 1-Methylhistamine Imidazole acetaldehyde Imidazoleacetic acid (IAA, IMA) 1-Methylimidazoleacetic acid 1,4-Methylimidazolacetic acid GABA Glutamate Putrescine γ-Aminobutyraldehyde (GABAL) N-Acetylputrescine N-Acetyl-γ-aminobutyraldehyde (N-acetyl-GABAL) N-Acetyl-γ-aminobutyric acid (N-acetyl-GABA)

v t e Trace amine-associated receptor modulators TAAR1Tooltip Trace amine-associated receptor 1 Agonists Endogenous Monoamine neurotransmitters Dopamine Histamine Epinephrine (adrenaline) Norepinephrine (noradrenaline) Serotonin Trace amines 3-Iodothyronamine 3-Methoxytyramine N-Methylphenethylamine N-Methyltyramine m-Octopamine p-Octopamine β-Phenethylamine Phenylethanolamine Synephrine Tryptamine m-Tyramine p-Tyramine Others Cyclohexylamine Isoamylamine Trimethylamine Exogenous 2C-B 2C-B-Fly 2C-E 2C-H 2C-P 2C-T-7 A-77636 2-Aminoindane Amphetamine AP163 Apomorphine Asenapine Bromocriptine Cathinone Chlorpromazine Clonidine Cyproheptadine Dihydroergotamine Dimethyltryptamine DOB DOET DOI DOM N,N-Dimethylphenethylamine Ergometrine Fenoldopam Fenoterol 4-Fluoroamphetamine Guanabenz Guanfacine Halostachine Higenamine Hordenine 4-Hydroxyamphetamine (norpholedrine) Idazoxan 5-Iodo-2-aminoindane Isoprenaline Isopropyloctopamine Lisuride LK00764 LSD LY03020 MDA (tenamfetamine) MDAI MDMA (midomafetamine) Mescaline Metergoline N-Methyl-2-AI 2-Methylphenethylamine 3-Methylphenethylamine 4-Methylphenethylamine β-Methylphenethylamine Methamphetamine MMA MPTP Naphazoline Nomifensine Norfenfluramine Oxymetazoline Phentermine Phentolamine o-PIT Psilocin Ralmitaront (RG-7906, RO6889450) RG-7351 RG-7410 RO5073012 RO5166017 RO5203648 RO5256390 RO5263397 S18616 Selegiline (L-deprenyl) Selutaront Solriamfetol Tolazoline Ulotaront (SEP-363856) Antagonists Compound 22 EPPTB (RO-5212773) RTI-7470-44 Inverse agonists EPPTB (RO-5212773) TAAR5Tooltip Trace amine-associated receptor 5 Agonists N,N-Dimethylethylamine Trimethylamine Inverse agonists 3-Iodothyronamine Notes: (1) TAAR1 activity of ligands varies significantly between species. Some agents that are TAAR1 ligands in some species are not in other species. This navbox includes all TAAR1 ligands regardless of species. (2) See the individual pages for references, as well as the List of trace amines, TAAR, and TAAR1 pages. See also: Receptor/signaling modulators

v t e Chemical classes of psychoactive drugs Stimulants Amphetamine-type/dopamine releasing agents: Alkylamines Cycloalkylaminopropanes Arylpiperazines Benzylpiperazines Phenylpiperazines Phenethylamines Aminorexes/phenyloxazolamines Amphetamines/α-methylphenethylamines Cathinones/β-ketoamphetamines β-Hydroxyamphetamines/cathinols Naphthylaminopropanes Phentermines Phenylisobutylamines/α-ethylphenethylamines α-Propylphenethylamines Phenylmorpholines/phenmetrazines Thiopropamines/thienylaminopropanes Cocaine-type/typical dopamine reuptake inhibitors: Phenethylamines Phenidates/benzylpiperidines Phenylethylpyrrolidines Pyrrolidinophenones Phenyltropanes/cocaine analogues Modafinil-type/atypical dopamine reuptake inhibitors: Modafinil analogues Phenylpiracetams Caffeine-type/adenosine receptor antagonists: Xanthines/methylxanthines Nicotine-type/nicotinic acetylcholine receptor agonists: Nicotine analogues Depressants GABAA receptor positive allosteric modulators: Alcohols/ethanol analogues Barbiturates Benzodiazepines Pyrrolobenzodiazepines Thienobenzodiazepines Thienodiazepines Thienotriazolodiazepines Triazolobenzodiazepines Carbamates Ethers Neuroactive steroids Nonbenzodiazepines β-Carbolines Cyclopyrrolones Imidazopyridines Pyrazolopyrimidines Phenols Piperidinediones Quinazolinones GABAA receptor agonists: Isoxazoles GHB receptor agonists: 1,4-Butanediols α2δ subunit-containing voltage-gated calcium channel blockers: Gabapentinoids Opioids/μ-opioid receptor agonists: Benzimidazoles Nitazenes Fentanyl analogues/phenylpiperidines Mitragyna alkaloids Morphinans/phenanthrenes Opiates/opium alkaloids Utopioids Antihistamines/H1 receptor antagonists: Benzimidazoles Diarylmethanes Ethylenediamines Tricyclics Dibenzocycloheptenes Hallucinogens Serotonergic psychedelics/serotonin 5-HT2A receptor agonists: Arylpiperazines Phenylpiperazines Quinolinylpiperazines Cyclized phenethylamines 3-Benzazepines Cyclized tryptamines Azepinoindoles Ibogalogs Iboga alkaloids β-Carbolines Harmala alkaloids Ergolines Lysergamides Simplified/partial lysergamides Phenethylamines (methoxyphenethylamines) 2Cs 25-NB/NBOMes 2C-Os 2C-Ts HOT-x TWEETIOs Amphetamines/α-methylphenethylamines 3Cs 3C-Desoxyscalines Dimethoxyamphetamines/DMAs DOx Alephs Ethylenedioxyamphetamines/EDxx Methylenedioxyamphetamines/MDxx Trimethoxyamphetamines/TMAs BOx Desoxyscalines FLYs/benzofurans Phenylisobutylamines/α-ethylphenethylamines 4Cs Scalines Thioscalines Ψ-PEAs Tryptamines α-Alkyltryptamines α-Alkyl-β-ketotryptamines 4-Hydroxytryptamines 5-Hydroxytryptamines 5-Methoxytryptamines Miscellaneous Dissociatives/NMDA receptor antagonists: Adamantanes Arylcyclohexylamines Diarylethylamines Morphinans κ-Opioid receptor agonists: Benzomorphans Salvinorins GABAA receptor agonists: Isoxazoles Deliriants/anticholinergics/muscarinic acetylcholine receptor antagonists: Diarylmethanes Tropanes Others: Cyclized tryptamines Azepinoindoles Iboga alkaloids (Phyto)cannabinoids Entactogens Serotonin releasing agents: Phenethylamines 2-Aminoindanes 2-Aminotetralins Amphetamines Benzofuranylaminopropanes Benzothiophenylaminopropanes Ethylenedioxyamphetamines/EDxx Indanylaminopropanes Indolylaminopropanes Methylenedioxyamphetamines/MDxx Tetralinylaminopropanes Tryptamines α-Alkyltryptamines Miscellaneous Psychiatric drugs Anxiolytics: Azapirones Benzodiazepines Pyrrolobenzodiazepines Thienobenzodiazepines Thienodiazepines Thienotriazolodiazepines Triazolobenzodiazepines Antidepressants: Tricyclic antidepressants Dibenzazepines Dibenzocycloheptenes Dibenzothiepins Dibenzoxazepines Dibenzoxepins Tetracyclic antidepressants Antipsychotics/dopamine D2 receptor antagonists or partial agonists: Benzamides Benzimidazoles Benzisothiazoles Benzisoxazoles Butyrophenones Diphenylbutylpiperidines Phenylpiperazines Tricyclics Dibenzazepines Dibenzodiazepines Dibenzothiazepines Dibenzothiepins Dibenzoxazepines Phenothiazines Thienobenzodiazepines Mood stabilizers/anticonvulsants: Gabapentinoids Tricyclics Dibenzazepines Valproates Others Nootropics: Racetams Phenylpiracetams Miscellaneous: 3-Benzazepines Adamantanes Catecholamines Tetrahydroisoquinolines Yohimbans

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Adapted from the Wikipedia article [Catecholamine](https://en.wikipedia.org/wiki/Catecholamine) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Catecholamine?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.