Neurotrophin

Neurotrophins (gr. about " nerves nutrients " ) are endogenous signal substances that cause targeted connections between nerve cells. They ensure the survival of neural connections. Neurotrophins are small basic proteins with a molecular mass of about 13 kDa.

Classification

There are five types of neurotrophins:

  • NGF - Nerve Growth Factor
  • BDNF - brain-derived neurotrophic factor
  • NT-3 - Neurotrophin 3
  • NT-4 - neurotrophin 4
  • NT -5 - 5 neurotrophin, as have NT -4 and NT -5 -like properties, they are often grouped together as NT - 4/5

These can bind to membrane receptors. There are two types of receptors for neurotrophins:

  • P75 neurotrophin receptor ( p75NTR ), a receptor of the TNF receptor family
  • Receptors of the tyrosine kinase receptor family ( Trk A, Trk B and Trk C)

The p75NTR is to bind all five neurotrophins able, but the affinity is relatively low. The receptors of the Trk family, however, are affine and specifically bind only certain neurotrophins:

  • Trk A - NGF
  • Trk B - BDNF, NT -4 and NT -5
  • Trk C - NT -3

The binding of neurotrophins to p75NTR leads to programmed cell death (see apoptosis) of the cell. Binding to receptors of the Trk family, however, triggers a cascade of kinases, the anti-apoptotic effect. The central enzyme of this mechanism is that, especially in the Anglo- American sphere, also known as " ACT " known protein kinase B. Because of this ambivalent behavior we see today neurotrophins no more than Neurostimulators, but as neuromodulators.

History

The term neurotrophin was introduced with the neurotrophin hypothesis of Viktor Hamburger and Rita Levi Montalcini -. It assumes that immature neurons compete for limited, proffered by target cells trophic factors. Only those neurons that link the successful synaptic connections, get enough of these trophic factors, in order to survive.

Neurons which do not receive sufficient trophic factors are removed by apoptosis.

Are neurotrophins are present, they bind to cell surface receptors of the Trk family. Then a cascade of kinases is triggered, cause their target proteins for suppression of apoptosis.

Psychology

Neurotrophins contribute to memory formation and play a major role in the construction and the mining of new nerve networks.

Experts in neurotrophin research at the Ruhr- University Bochum suggest that changing the neurotrophin - values ​​falling in love. Scientists at the Italian University of Pavia placed increased neurotrophin - values ​​determined for loving subjects and suggest that this is responsible for the typical euphoria at the beginning of a love romance. After a year of no more increased values ​​were found.

Digital Object Identifier
599325
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