This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (January 2008)

Figure 1. The seven transmembrane α-helix structure of a G-protein-coupled receptor.

A neurotransmitter receptor is a membrane receptor protein. A membrane protein interacts with the lipid bilayer that encloses the cell ^[1] and a membrane receptor protein interacts with a chemical in the cells external environment, which binds to the cell ^[2] . Membrane receptor proteins are particularly important in neuronal and glial (involved in neuronal transmission, but not technically neurons) cells, because they allow cells to communicate with one another through chemical signals. Neurotransmitter receptors send and receive signals that trigger an electrical signal that runs along the neuron and can be passed along a neural network, by regulating the activity of ion channels ^[3] A neurotransmitter receptor can be paired directly with an ion channel, but most send signals indirectly though guanyl nucleotide-binding proteins or G proteins ^[4] Interactions between neurotransmitters and neurotransmitter receptors are involved in a wide range of differing reactions from the cell receiving the signal, triggering anything from activation to inhibition.

[edit] Ion channel coupled neurotransmitter receptors

[edit] Desensitization and ligand concentration

One additional characteristic of neurotransmitter receptors is that they are subject to ligand-induced desensitization: That is, they can become unresponsive upon prolonged exposure to their neurotransmitter. Neurotransmitter receptors are present on both postsynaptic neurons and presynaptic neurons with the former being used to receive neurotransmitters and the latter for the purpose of preventing further release of a given neurotransmitter[1]. In addition to being found in neuron cells, neurotransmitter receptors are also found in various immune and muscle tissues[2]. Many neurotransmitter receptors are categorized as a serpentine receptor or G protein-coupled receptor because they span the cell membrane not once, but seven times. Neurotransmitter receptors are known to become unresponsive to the type of neurotransmitter they receive when exposed for extended periods of time. This phenomenon is known as ligand-induced desensitization[3] or downregulation.

[edit] Table of neurotransmitters

Neurotransmitters

[edit] Known neurotransmitter receptors (table2)^[5]

• Adrenergic

  α1A, α1b, α1c, α1d  α2a, α2b, α2c, α2d  β1, β2, β3 

• Dopaminergic

  D1, D2, D3, D4, D5 

• GABAergic

  GABAA, GABAB1a, GABAB1δ, GABAB2, GABAC 

• Glutaminergic

  NMDA, AMPA kainate, mGluR1, mGluR2, mGluR3, mGluR4, mGluR5, mGluR6, mGluR7 

• Histaminergic

  H1, H2, H3 

• Cholinergic

  Muscarinic: M1, M2, M3, M4, M5  Nicotinic: muscle, neuronal (α-bungarotoxin-insensitive), neuronal (α-bungarotoxin-sensitive) 

• Opioid

  μ, δ1, δ2, κ 

• Serotonergic

  5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, 5-HT1F, 5-HT2A, 5-HT2B, 5-HT2C, 5-HT3, 5-HT4, 5-HT5, 5-HT6, 5-HT7 

• Glycinergic

  Glycine 

[edit] See also

• Autoreceptor
• Receptor desensitization has been previously modeled in the context of a two-state mathematical model (see this link [14])
• Synaptic Transmission
• Neuromuscular transmission
• Catecholamines
• Cholinergic Agonists and Antagonists

[edit] Notes and references

[edit] External links

• MeSH Neuroregulator+Receptor