Implication of brain-derived neurotrophic factor in the release of dopamine and dopamine-related behaviors induced by methamphetamine.

It is widely recognized that methamphetamine enhances the release of dopamine at dopaminergic neuron terminals of the mesolimbic system, which induces dopamine-related behaviors. Brain-derived neurotrophic factor (BDNF), a neurotrophin, binds to and activates its specific receptor tyrosine kinase, TrkB. BDNF has been shown to influence the release of dopamine in the mesolimbic dopamine system. The present study was designed to investigate roles of BDNF and TrkB in the expression of methamphetamine-induced dopamine release in the nucleus accumbens and dopamine-related behaviors induced by methamphetamine in rats. Methamphetamine (1 mg/kg, s.c.) produced a substantial increase in the extracellular levels of dopamine and induced a progressive augmentation of dopamine-related behaviors such as rearing and sniffing. In contrast, both the stimulation of dopamine release and induction of dopamine-related behaviors by methamphetamine were significantly suppressed by pretreatment with intra-nucleus accumbens injection of either BDNF (2.0 microl/rat, 1:1000, 1:300 and 1:100) or TrkB (2.0 microl/rat, 1:1000 and 1:100) antibody. Furthermore, the basal level of dopamine in the nucleus accumbens was not affected by treatment with both BDNF and TrkB antibodies. These findings provide further evidence that BDNF/TrkB pathway is implicated in the methamphetamine-induced release of dopamine and the induction of dopamine-related behaviors.