In vivo and in vitro inhibition of human chorionic gonadotropin-induced testosterone production in rat testis by bursa of fabricius extract.

A bursa of Fabricius homogenate extract (BHE) was used to investigate the endocrine regulation function of this avian organ. In vivo and in vitro results indicated that BHE inhibited human chorionic gonadotropin (HCG)-induced testosterone production by rat testes. Leydig cells from collagenase-dispersed rat testes, when treated with BHE, showed a dose-response related depression of testosterone production under HCG stimulation. Young male rats, injected simultaneously with BHE and HCG, failed to show the marked testosterone production peak observed in rats injected with HCG only. However, in vivo treatments with BHE, in the absence of HCG stimulation, did not inhibit basal testosterone production. These results indicate that the bursa of Fabricius produces an endocrine regulation factor that inhibits HCG-induced testosterone production both in vivo and in vitro. Further investigation is necessary to isolate the active factor and determine its mechanism of action.