New neurons are incorporated into the high vocal center (HVC), a nucleus of
the adult canary (Serinus canaria) brain that plays a critical role in the
acquisition and production of learned song. Recruitment of new neurons in
the HVC is seasonally regulated and depends upon testosterone levels. We sh
ow here that brain-derived neurotrophic factor (BDNF) is present in the HVC
of adult males but is not detectable in that of females, though the HVC of
both sexes has BDNF receptors (TrkB). Testosterone treatment increases the
levels of BDNF protein in the female HVC, and BDNF infused into the HVC of
adult females triples the number of new neurons. Infusion of a neutralizin
g antibody to BDNF blocks the testosterone-induced increase in new neurons.
Our results demonstrate that BDNF is involved in the regulation of neurona
l replacement in the adult canary brain and suggest that the effects of tes
tosterone are mediated through BDNF.