When reading
articles about neuroepigenetics, one frequently comes across BDNF, which stands
for brain-derived neurotrophin factor. Neurotrophins are a class of
proteins which are important in neuron growth, development of synapses, neuron
regeneration, dendritic arborization, neuron differentiation, learning and memory
among other things. They are therefore essential for proper brain
development and lifelong plasticity. They are secreted by neurons and may
act on the cell itself or on neighboring cells but can also be transported over
longer distances via the axon. BDNF in particular has been linked to activity
dependent neuronal plasticity and therefore learning, as it is for example
upregulated by Calcium-ion influx into the neuron. It seems to be involved in
certain slower but more lasting changes in neuron connectivity, as it leads to
changes in the number of dendritic spines and certain neurotransmitter receptors.
Injecting BDNF into certain brain areas can enhance learning in mice. Also, without
the ability to produce BDNF, mice die early due to severe abnormalities in
brain development. Aberrant methylation of BDNF genes in humans, that is,
epigenetic changes in how BDNF is produced or detected in the neuron, have been
implicated in stress regulation, mood, long-term memory deficits, depression,
PTSD, addiction, and schizophrenia. On the other hand, antidepressiva and
physical activity lead to an increase in BDNF concentrations, which might be an
explanation for why these two factors are linked with enhanced brain plasticity. The ways
in which BDNF shapes the brain and mediates cognitive and affective functions is however still not completely understood and in parts controversial and therefore requires further research.
Sources:
Cunha, C., Brambilla, R., & Thomas, K. L. (2010). A simple role for
BDNF in learning and memory?. Frontiers in molecular
neuroscience, 3, 1.
Huang, E. J., & Reichardt, L. F. (2001). Neurotrophins: roles in
neuronal development and function. Annual review of neuroscience, 24(1), 677-736.
Kowiański, P., Lietzau, G.,
Czuba, E., Waśkow, M., Steliga, A., & Moryś, J. (2018). BDNF: a key factor with
multipotent impact on brain signaling and synaptic plasticity. Cellular and molecular neurobiology, 38(3), 579-593.
Groves, J. O. (2007). Is it time to reassess the BDNF hypothesis of depression?.
Molecular psychiatry,
12(12), 1079-1088.
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