The Role of BDNF Gene Polymorphism in Formation of Clinical Characteristics of Migraine

Brain-derived neurotrophic factor (BDNF) is a neurotrophin presented widely in central nervous system (CNS). The general function of BDNF in CNS is maintaining neuronal viability in ischemic condition, as well as providing neuronal plasticity and modulating behavioral activity. BDNF regulates axonal growth and differentiation of neurons; synapse formation; activity of dopaminergic, serotoninergic, GABA-ergic, and cholinergic neurons. BDNF also supports cognitive processes such as learning and memory. BDNF modulates both activating and inhibiting synapses affecting sodium channels and thus regulating neuronal excitability. Human BDNF gene is located in 11p14.1 region. It has 9 promoters and 11 exons. The sequence that encodes functional protein resides in the last exon. Alternative promoters provide 9 tissueand time-specific transcripts that encode various leading peptides of pre-pro-protein BDNF [1,2]. The gene is expressed in nociceptive sensory neurons modulating metabotropic and ionotropic glutamate receptors. BDNF mRNA is translated into pre-pro-BDNF which is then processed into pro-BDNF and delivered to synapse. In the synapse, pro-BDNF is processed to form functional BDNF molecule. Targets of BDNF are tyrosine kinase receptors (TrkB). Activation of TrkB receptors triggers cascades that provide biological effects of BDNF (see Figure 1):