brain-derived neurotrophic factor (BDNF)

introduction

a member of the neurotrophin neural growth factor family and is a secreted protein
it helps to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses
it is active in the hippocampus, cortex, and basal forebrain — areas vital to learning, memory, and higher thinking, particularly important for long-term memory
it is also expressed in the retina, the central nervous system, motor neurons, the kidneys, and the prostate, and is found in saliva.
BDNF increases in brain tissue:
- acute voluntary exercise
- upregulated by caffeine
- sleep deprivation
- ECT therapy
- antidepressants
- curcumin
- intellectual stimulation
- caloric restriction
- glutamate as a excitatory neurotransmitter
BDNF appears to be down-regulated by air pollution, stress, depression and corticosteroids, hence the potential for these factors to impair learning and memory, and perhaps also contribute to depression
it binds to:
- cell surface receptors:
  - TrkB
    - a tyrosine kinase based receptor and the primary receptor for BDNF and NT-4
  - LNGFR (for low-affinity nerve growth factor receptor, also known as p75)
    - may have a role in apoptosis
may also modulate the activity of various neurotransmitter receptors, including the α7 nicotinic receptor
interacts with the reelin signaling chain
may have a role in many disease states including:
- depression
- epilepsy
- drug dependency
- many psychiatric conditions
- neurodegenerative conditions such as dementia
- high levels appear to be present in patients with severe itching due to eczema
- congenital central hypoventilation syndrome