Btf

Brain-derived neurotrophic factor (BDNF) is a protein that, in humans, is encoded by the BDNF gene. BDNF is a member of the neurotrophin family of growth factors, which are related to the canonical nerve growth factor (NGF). Neurotrophic factors are found in the brain and the peripheral nervous system.

Function

BDNF acts on certain neurons of the central nervous system (CNS) and the peripheral nervous system (PNS), helping to support the survival of existing neurons, and encouraging the growth and differentiation of new neurons and synapses. In the brain, it is active in the hippocampus, cortex, and basal forebrain—areas vital to learning, memory, and higher thinking. BDNF itself is important for long-term memory.

Mechanism of Action

BDNF binds to at least two receptors on the surface of cells: the TrkB (pronounced "Track B") receptor and the LNGFR (low-affinity nerve growth factor receptor, also known as p75). The binding of BDNF to TrkB initiates a signaling cascade that leads to the activation of several intracellular pathways, including the MAPK/ERK pathway, the PI3K/Akt pathway, and the PLCγ pathway. These pathways are involved in cell survival, synaptic plasticity, and neuronal differentiation.

Role in the Nervous System

BDNF is crucial for the development and maintenance of the nervous system. It is involved in:

• Neurogenesis: BDNF promotes the growth and differentiation of new neurons from neural stem cells.
• Synaptic plasticity: BDNF enhances synaptic transmission and plasticity, which are essential for learning and memory.
• Neuronal survival: BDNF supports the survival of neurons by inhibiting apoptotic pathways.

Clinical Significance

BDNF has been implicated in several neurological and psychiatric disorders. Altered levels of BDNF have been associated with conditions such as:

• Depression: Reduced levels of BDNF have been observed in patients with depression, and antidepressant treatments have been shown to increase BDNF levels.
• Schizophrenia: Abnormal BDNF signaling may contribute to the pathophysiology of schizophrenia.
• Alzheimer's disease: BDNF levels are decreased in the brains of patients with Alzheimer's disease, and it is thought to play a role in the disease's progression.
• Parkinson's disease: BDNF may have a protective effect on dopaminergic neurons, which are affected in Parkinson's disease.

Therapeutic Potential

Given its role in neuronal survival and plasticity, BDNF is a target for therapeutic interventions in various neurological disorders. Strategies to increase BDNF levels or mimic its activity are being explored, including:

• Exercise: Physical activity has been shown to increase BDNF levels in the brain.
• Dietary interventions: Certain diets, such as the Mediterranean diet, may influence BDNF levels.
• Pharmacological agents: Drugs that enhance BDNF signaling or mimic its effects are under investigation.

Genetics

The BDNF gene is located on chromosome 11p14.1. It is highly polymorphic, with several known single nucleotide polymorphisms (SNPs) that can affect its expression and function. One of the most studied SNPs is the Val66Met polymorphism, which has been associated with altered activity-dependent secretion of BDNF and various neuropsychiatric disorders.

See Also

• Neurotrophin
• Nerve growth factor
• TrkB
• Neurogenesis