These authors contributed equally.
Aromatase, brain sexualization and plasticity: the fish paradigm
Article first published online: 12 DEC 2010
© 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd
European Journal of Neuroscience
Special Issue: Plasticity of Neuroendocrine Systems
Volume 32, Issue 12, pages 2105–2115, December 2010
How to Cite
Le Page, Y., Diotel, N., Vaillant, C., Pellegrini, E., Anglade, I., Mérot, Y. and Kah, O. (2010), Aromatase, brain sexualization and plasticity: the fish paradigm. European Journal of Neuroscience, 32: 2105–2115. doi: 10.1111/j.1460-9568.2010.07519.x
- Issue published online: 12 DEC 2010
- Article first published online: 12 DEC 2010
- Received 28 August 2010, revised 5 October 2010, accepted 6 October 2010
- radial glial cell;
In contrast to mammals, teleost fish have a very labile genetic sex determination. Sex differentiation is influenced by a combination of hormonal, social and environmental factors and teleost fishes exhibit many examples of hermaphroditism. This means that the brain of fish is not irreversibly sexualized early in life. This review aims at highlighting some unique features of fish that may explain their brain sexual plasticity. Unlike mammals, in which brain aromatase activity decreases after birth, adult teleosts exhibit an intense aromatase activity due to strong expression of one of two aromatase genes (aromatase A or cyp19a1a and aromatase B or cyp19a1b) that arose from a gene duplication event. Interestingly, aromatase B is only expressed in radial glial cells (RGC) of adult fish. These cells persist throughout life and act as progenitors in the brain of both developing and adult fish. In agreement with the fact that brain aromatase activity is correlated with sex steroid levels, the high expression of cyp19a1b is due to an autoregulatory loop through which estrogens and aromatizable androgens upregulate aromatase expression. Given the well-established roles of estrogens and aromatase on brain sexualization, these features suggest that the brain of fish conserves properties of embryonic mammalian brain throughout life – high neurogenic activity and high aromatase expression in progenitor cells correlated with sex steroid levels. The permanent dialogue between the brain and the gonad would permit sex changes and thus the emergence of a variety of reproductive strategies. Other hypotheses are also discussed.