Wikia

Psychology Wiki

Neurotransmitters

Talk0
34,141pages on
this wiki
Revision as of 17:26, November 15, 2011 by Dr Joe Kiff (Talk | contribs)

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)


File:Aspartic Acid.png

Neurotransmitters are chemicals that are used to relay, amplify and modulate signals between a neuron and another cell. It does this through the process of receptor binding to a neuroreceptor, which triggers aresponse in the neuron to alter its functioning.

According to the prevailing beliefs of the 1960s, a chemical can be classified as a neurotransmitter if it meets the following conditions:

  • There are precursors and/or synthesis enzymes located in the presynaptic side of the synapse;
  • The chemical must be present in the presynaptic element
  • It is available in sufficient quantity in the presynaptic neuron to affect the postsynaptic neuron;
  • There must be postsynaptic receptors and the ability for the chemical to bind to said receptors
  • A biochemical mechanism for inactivation must be present.

Types of neurotransmitters

There are many different ways to classify neurotransmitters. Often, dividing them into amino acids, peptides, and monoamines is sufficient for many purposes.

Some more precise divisions are as follows:

The major "workhorse" neurotransmitters of the brain are glutamic acid and GABA.

Effects

Some examples of neurotransmitter action:

  • Acetylcholine - voluntary movement of the muscles
  • Norepinephrine - wakefulness or arousal
  • Dopamine - voluntary movement and motivation, "wanting", pleasure, associated with addiction and love
  • Serotonin - memory, emotions, wakefulness, sleep and temperature regulation
  • GABA - inhibition of motor neurons
  • Glycine - spinal reflexes and motor behaviour
  • Neuromodulators - sensory transmission - especially pain

Neurotransmitter systems

Main article: Neurotransmitter systems

Neurons expressing certain types of neurotransmitters sometimes form distinct systems, where activation of the system causes effects in large volumes of the brain, called volume transmission.

The major neurotransmitter systems are the noradrenaline (norepinephrine) system, the dopamine system, the serotonin system and the cholinergic system.

Drugs targeting the neurotransmitter of such systems affects the whole system, and explains the mode of action of many drugs;

Diseases may affect specific neurotransmitter systems. For example, Parkinson's disease is at least in part related to failure of dopaminergic cells in deep-brain nuclei, for example the substantia nigra. Treatments potentiating the effect of dopamine precursors have been proposed and effected, with moderate success.

A brief comparison of the major neurotransmitter systems follows:

Neurotransmitter systems
System Origin [1] Effects[1]
Noradrenaline system locus coeruleus
  • arousal
  • reward
Lateral tegmental field
Dopamine system dopamine pathways: motor system, reward, cognition, endocrine, nausea
Serotonin system caudal dorsal raphe nucleus Increase (introverson), mood, satiety, body temperature and sleep, while decreasing nociception.
rostral dorsal raphe nucleus
Cholinergic system pontomesencephalotegmental complex
basal optic nucleus of Meynert
medial septal nucleus

Common neurotransmitters

Category Name Abbreviation Metabotropic Ionotropic
Small: Amino acids Aspartate - -
Neuropeptides N-Acetylaspartylglutamate NAAG Metabotropic glutamate receptors; selective agonist of mGluR3 -
Small: Amino acids Glutamate (glutamic acid) Glu Metabotropic glutamate receptor NMDA receptor, Kainate receptor, AMPA receptor
Small: Amino acids Gamma-aminobutyric acid GABA GABAB receptor GABAA receptor, GABAC receptor
Small: Amino acids Glycine Gly - Glycine receptor
Small: Acetylcholine Acetylcholine Ach Muscarinic acetylcholine receptor Nicotinic acetylcholine receptor
Small: Monoamine (Phe/Tyr) Dopamine DA Dopamine receptor -
Small: Monoamine (Phe/Tyr) Norepinephrine (noradrenaline) NE - -
Small: Monoamine (Phe/Tyr) Epinephrine (adrenaline) Epi - -
Small: Monoamine (Phe/Tyr) Octopamine - -
Small: Monoamine (Phe/Tyr) Tyramine -
Small: Monoamine (Trp) Serotonin (5-hydroxytryptamine) 5-HT Serotonin receptor, all but 5-HT3 5-HT3
Small: Monoamine (Trp) Melatonin Mel Melatonin receptor -
Small: Monoamine (His) Histamine H Histamine receptor -
PP: Gastrins Gastrin - -
PP: Gastrins Cholecystokinin CCK Cholecystokinin receptor -
PP: Neurohypophyseals Vasopressin Vasopressin receptor -
PP: Neurohypophyseals Oxytocin Oxytocin receptor -
PP: Neurohypophyseals Neurophysin I - -
PP: Neurohypophyseals Neurophysin II - -
PP: Neuropeptide Y Neuropeptide Y NY Neuropeptide Y receptor -
PP: Neuropeptide Y Pancreatic polypeptide PP - -
PP: Neuropeptide Y Peptide YY PYY - -
PP: Opioids Corticotropin (adrenocorticotropic hormone) ACTH Corticotropin receptor -
PP: Opioids Dynorphin - -
PP: Opioids Endorphin - -
PP: Opioids Enkephaline - -
PP: Secretins Secretin Secretin receptor -
PP: Secretins Motilin Motilin receptor -
PP: Secretins Glucagon Glucagon receptor -
PP: Secretins Vasoactive intestinal peptide VIP Vasoactive intestinal peptide receptor -
PP: Secretins Growth hormone-releasing factor GRF - -
PP: Somtostatins Somatostatin Somatostatin receptor -
SS: Tachykinins Neurokinin A - -
SS: Tachykinins Neurokinin B - -
SS: Tachykinins Substance P - -
PP: Other Bombesin - -
PP: Other Gastrin releasing peptide GRP - -
Gas Nitric oxide NO - -
Gas Carbon monoxide CO - -
Other Anandamide AEA Cannabinoid receptor -
Other Adenosine triphosphate ATP P2Y12 P2X receptor

Production and destruction cycles

When neurotransmitters are released into the synapse only some binds with receptors, the rest may be broken down by enzymes in the synaptic fluid or is reabsorbed quickly into the presynaptic neuron via a reuptake transporter pump. This allows for the neurotransmitter to be repackaged in the vesicles and to be recycled. So, for example, monoamine transporter are structures in nerve-cell membranes which function as neurotransmitter transporters transferring monoamine neurotransmitters in or out of cells. Some psychiatric drugs work by effecting this process

Genetic control of neurotransmitters

Many of these neurochemicals have been studied with a view to identifying the genetic mechanisms underlying their production and control

Main article: Genetic factors influencing neurotransmitter production and action





See also

References & Bibliography

Key texts

Books

  • Kopn,L.J. (ed.) Neurotransmitters, Baltmore: Williams & Wilkins.


Papers

Additional material

Books

Papers

References

  1. 1.0 1.1 Rang, H. P. (2003). Pharmacology, page 474 for noradrenaline system, page 476 for dopamine system, page 480 for serotonin system and page 483 for cholinergic system., Edinburgh: Churchill Livingstone.

External links

Commons-logo
Wikimedia Commons has media related to:


|}

This page uses Creative Commons Licensed content from Wikipedia (view authors).

Around Wikia's network

Random Wiki