Fadrozole induces delayed effects on neurons in the zebra finch song system.

To analyse the influences of estradiol on the differentiation of neurons in the song motor centers RA (robust nucleus of the archistriatum) and HVc (higher vocal center), juvenile male zebra finches were treated with the aromatase inhibitor, Fadrozole (CGS 16949A). The differentiation of neurons was determined by measuring neuronal soma sizes. As adults the treated animals showed a significant shift in the distribution of neuron sizes towards smaller cell diameters in both areas. The neuroanatomical modulation caused by Fadrozole was not accompanied by changes in song behaviour.