Aromatase in radial glial progenitors of fish brain: evolutive novelty or conserved feature of vertebrates.

KAH, OLIVIER; MAURIEC, KAREN; DIOTEL, NICOLAS; VAILLANT, COLETTE; LE BOUC, MARIE; THIEULANT, MARIE-LOUISE; PELLEGRINI, ELISABETH; SOMOZA, GUSTAVO M.

Hong Kong, China.

Congreso; 16th International Congress of Comparative Endocrinology; 2009

The interest of comparing models to get insights into evolutive mechanisms and to understand the true meaning of some biological mechanisms is well exemplified by recent findings in different vertebrates suggesting a strong functional link between neurosteroid synthesis and neurogenesis.   Two intriguing features of the brain of fish are indeed the dramatic expression of aromatase and its high capacity to grow during adulthood. Recent data showing that aromatase, the estrogen synthesizing enzyme, is in fact expressed in radial glial cells and that such cells are neuronal progenitors in adults have further stimulated the interest in the potential roles of estrogens, not only in neuroprotection, but also in neurogenesis and brain repair. This lecture will present some comparative data suggesting that the intriguing situation observed in fish may well represent an exaggerated use of a more general mechanism present in other vertebrates during embryonic or reparative neurogenesis. Indeed, there is now growing evidence in birds and mammals that radial cells or astrocytes synthesize estrogens during embryonic, adult or reparative neurogenesis, bringing together separate pieces of a complex puzzle. Therefore, it is likely that the brain of fish, “adult” in terms of sexual status, keeps using mechanisms involved in the “immature” developing brain of birds and mammals.  Supported by CNRS, the ANR, the European Union and ECOs-Sud