Follicle-Stimulating Hormone Regulates Gene Expression Directly or Downstream Effectors to Modulate Igf3 Effects on Zebrafish Spermatogenesis.

Previous work showed that pharmacological inactivation of Igf-binding proteins (Igfbps), modulators of Igf activity, resulted in an excessive differentiation of type A undifferentiated (A) spermatogonia in zebrafish testis in tissue culture when Fsh was present in the incubation medium. Using this testis tissue culture system, we studied here the regulation of transcript levels by Fsh and two of its downstream effectors, Igf3 and 11-ketotestosterone (11-KT). We also explored how Fsh-modulated expression affected spermatogonial proliferation by adding or removing the Igfbp inhibitor NBI-31772 at different times.