Monoamine neurotransmitter

Norepinephrine is a monoamine neurotransmitter

A phylogenetic tree showing how a number of monoamine receptors are related to each other.

Monoamine neurotransmitters are neurotransmitters and neuromodulators that contain one amino group that is connected to an aromatic ring by a two-carbon chain (-CH₂-CH₂-). All monoamines are derived from aromatic amino acids like phenylalanine, tyrosine, tryptophan, and the thyroid hormones by the action of aromatic amino acid decarboxylase enzymes. The function of monoamine is not clear but it is thought to trigger crucial components such as emotion, arousal, and cognition. It has however been found that monoamine neurotransmitters play an important role in the secretion and production of neurotriphin-3 by astrocytes, a chemical which maintains neuron integrity and provides neurons with trophic support. Drugs used to increase the effect of monoamine may be used to treat patients with psychiatric disorders, including depression, anxiety, and schizophrenia.

Examples

• Histamine (His/H is Diamine)
• Catecholamines:
  • Dopamine (DA)
  • Noradrenaline (NA, NAd) (Norepinephrine, NE)
  • Adrenaline (Ad) (Epinephrine, Epi)
• Tryptamines:
  • Serotonin (5-HT)
  • Melatonin
• Trace amines:
  • β-Phenylethylamine (PEA, β-PEA)
  • Tyramine
  • Tryptamine
  • Octopamine
  • 3-Iodothyronamine
  • Thyronamines, a new group of compounds derived from thyroid hormones

Specific transporter proteins called monoamine transporters that transport monoamines in or out of a cell exist. These are the dopamine transporter (DAT), serotonin transporter (SERT), and the norepinephrine transporter (NET) in the outer cell membrane and the vesicular monoamine transporter (VMAT1 and VMAT2) in the membrane of intracellular vesicles.^{[citation needed]}

After release into the synaptic cleft, monoamine neurotransmitter action is ended by reuptake into the presynaptic terminal. There, they can be repackaged into synaptic vesicles or degraded by the enzyme monoamine oxidase (MAO), which is a target of monoamine oxidase inhibitors, a class of antidepressants.^{[citation needed]}

Evolution

As demonstrated by the wide existence of monoamine transmitters, an organism's ability to modify its behavior is advantageous to its survival. This system is found in various species such as nematodes, lobsters, desert locusts, hens, mice and zebra finches.

Disorders

Disorders of monoamine neurotransmitters exist, part of a growing number of neurotransmitter disorders identified. Such disorders are responsible for biosynthesis degradation and difficulty in transporting neurotransmitters such as dopamine, norepinephrine, epinephrine, or serotonin. Monoamine neurotransmitter disorders mimic the symptoms of other more prevalent neurological disorders (e.g. cerebral palsy) and thus are frequently misdiagnosed.

See also

• Monoamine oxidase
• Monoamine transporter
• Neurotransmitter
• Monoamine Hypothesis
• Biogenic amine
• Trace amine

External links

• Biogenic monoamines at the US National Library of Medicine Medical Subject Headings (MeSH)