Neuromelanin

Neuromelanin (NM) is a dark pigment found in the brain which is structurally related to melanin.wikipedia
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Melanin

eumelaninpheomelaninphaeomelanin
Neuromelanin (NM) is a dark pigment found in the brain which is structurally related to melanin. It is a polymer of 5,6-dihydroxyindole monomers.
There are three basic types of melanin: eumelanin, pheomelanin, and neuromelanin.

Substantia nigra

substantia nigra pars reticulatanigralsubstantia nigra pars compacta
Neuromelanin is found in large quantities in catecholaminergic cells of the substantia nigra pars compacta and locus coeruleus, giving a dark color to the structures.
Substantia nigra is Latin for "black substance", reflecting the fact that parts of the substantia nigra appear darker than neighboring areas due to high levels of neuromelanin in dopaminergic neurons.

Locus coeruleus

locus ceruleuslocus coereuleuslocus coeruleus-noradrenergic system
Neuromelanin is found in large quantities in catecholaminergic cells of the substantia nigra pars compacta and locus coeruleus, giving a dark color to the structures.
The neuromelanin is formed by the polymerization of noradrenaline and is analogous to the black dopamine-based neuromelanin in the substantia nigra.

Catecholamine

catecholaminescatecholamine synthesiscatecholamine systems
Neuromelanin biosynthesis is driven by excess cytosolic catecholamines not accumulated by synaptic vesicles.
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 ventral tegmental area and the substantia nigra, the latter of which contains neuromelanin-pigmented neurons.

Neuron

neuronsnerve cellsnerve cell
Neuromelanin-containing neurons in the substantia nigra undergo neurodegeneration during Parkinson's disease.
Some neurons also contain pigment granules, such as neuromelanin (a brownish-black pigment that is byproduct of synthesis of catecholamines), and lipofuscin (a yellowish-brown pigment), both of which accumulate with age.

Pars compacta

substantia nigra pars compactaSNc
The death of neuromelanin-containing neurons in the substantia nigra, pars compacta, and locus coeruleus have been linked to Parkinson's disease and also have been visualized in vivo with neuromelanin imaging.
In humans, the nerve cell bodies of the pars compacta are coloured black by the pigment neuromelanin.

Dopamine

dopaminergic systemDAdopaminergic
Neuromelanin is directly biosynthesized from L-DOPA, precursor to dopamine, by tyrosine hydroxylase (TH) and aromatic acid decarboxylase (AADC).
However, there is substantial evidence that the neuromelanin that gives a dark color to the brain's substantia nigra is at least in part dopamine-melanin.

Jan Evangelista Purkyně

PurkyněJan Evangelista PurkyneJan Purkinje
Dark pigments in the substantia nigra were first described in 1838 by Purkyně, and the term neuromelanin was proposed in 1957 by Lillie, though it has been thought to serve no function until recently.
Purkyně was also the first to describe and illustrate in 1838 the intracytoplasmic pigment neuromelanin in the substantia nigra.

MRI sequence

gradient echosequenceTurbo spin echo
The death of neuromelanin-containing neurons in the substantia nigra, pars compacta, and locus coeruleus have been linked to Parkinson's disease and also have been visualized in vivo with neuromelanin imaging.
This method exploits the paramagnetic properties of neuromelanin and can be used to visualize the substantia nigra and the locus coeruleus.

Pigment

pigmentspigmentationnatural pigment
Neuromelanin (NM) is a dark pigment found in the brain which is structurally related to melanin.

Polymer

polymershomopolymerpolymeric
It is a polymer of 5,6-dihydroxyindole monomers.

Catecholaminergic cell groups

catecholaminergic cells
Neuromelanin is found in large quantities in catecholaminergic cells of the substantia nigra pars compacta and locus coeruleus, giving a dark color to the structures.

Silver staining

silver stainsilverMethenamine silver stain
It is insoluble in organic compounds, and can be labeled by silver staining.

Toddler

toddlerstoddletoddlerhood
Neuromelanin is found to accumulate during aging, noticeably after the first 2–3 years of life.

Oxidative stress

oxidative damageoxidant stressoxidative
It is believed to protect neurons in the substantia nigra from iron-induced oxidative stress.

Radical (chemistry)

free radicalradicalfree radicals
It is considered a true melanin due to its stable free radical structure and it avidly chelates metals.

L-DOPA

levodopa L -DOPADOPA
Neuromelanin is directly biosynthesized from L-DOPA, precursor to dopamine, by tyrosine hydroxylase (TH) and aromatic acid decarboxylase (AADC).

Aromatic L-amino acid decarboxylase

DOPA decarboxylasearomatic L -amino acid decarboxylasearomatic amino acid decarboxylase
Neuromelanin is directly biosynthesized from L-DOPA, precursor to dopamine, by tyrosine hydroxylase (TH) and aromatic acid decarboxylase (AADC).

Synaptic vesicle

synaptic vesiclesvesiclesvesicle
Alternatively, synaptic vesicles and endosomes accumulate cytosolic dopamine (via vesicular monoamine transporter 2 (VMAT2) and transport it to mitochondria where it is metabolized by monoamine oxidase.

Cytosol

cytosolichyaloplasmintracellular fluid
Neuromelanin biosynthesis is driven by excess cytosolic catecholamines not accumulated by synaptic vesicles. Alternatively, synaptic vesicles and endosomes accumulate cytosolic dopamine (via vesicular monoamine transporter 2 (VMAT2) and transport it to mitochondria where it is metabolized by monoamine oxidase.

Vesicular monoamine transporter 2

VMAT2VMAT 2 2
Alternatively, synaptic vesicles and endosomes accumulate cytosolic dopamine (via vesicular monoamine transporter 2 (VMAT2) and transport it to mitochondria where it is metabolized by monoamine oxidase.

Mitochondrion

mitochondriamitochondrialmitochondrial membrane
Alternatively, synaptic vesicles and endosomes accumulate cytosolic dopamine (via vesicular monoamine transporter 2 (VMAT2) and transport it to mitochondria where it is metabolized by monoamine oxidase.

L-Dopaquinone

dopaquinone L -Dopaquinone
Excess dopamine and DOPA molecules are oxidized by iron catalysis into dopaquinones and semiquinones which are then phagocytosed and are stored as neuromelanin.

Primate

primatesnon-human primatesnon-human primate
Neuromelanin is found in higher concentrations in humans than in other primates.

Neuroprotection

neuroprotectiveneuroprotectantneuroprotective agent
Neuromelanin concentration increases with age, suggesting a role in neuroprotection (neuromelanin can chelate metals and xenobiotics ) or senescence.