Aromatase B is expressed in progenitor cells in the brain of adult zebrafish
Brain aromatization of androgens is particularly important for the organization of sexually dimorphic structures in the brain, testosterone feedback on neuroendocrine circuits controlling the reproductive axis, and regulation of sexual behavior. The brain of teleost fish is characterized by a high aromatase activity corresponding to expression of Aromatase B (AroB) (cyp19b), one of two cyp19 duplicates. In teleost species, including the zebrafish, it was shown that Aromatase B (AroB) is expressed in radial glial cells. Given the well-known role of radial glial cells as progenitor cells during embryogenesis, we examined the possibility that Aromatase B radial cells are progenitor cells in the brain of adult fish using a combination of BrdU treatment and immunohistochemistry. We demonstrate for the first time, that aromatase-positive radial cells actively divide to generate newborn cells in many forebrain regions. These data provide new evidence for the mechanisms underlying adult neurogenesis in fish. Given that estrogens are known to affect proliferation, apoptosis, migration and differentiation, expression of Aromatase B (AroB) in progenitor cells is likely to affect adult neurogenesis under certain physiological conditions.