Immunolocalization of Inhibin/Activin Subunits in Equine Fetal Adrenal Glands during Mid Gestation

Abstract

To elucidate the function of inhibin/activin subunits in developmental fetal adrenal glands, we investigated immunolocalization of inhibin α and inhibin/activin (β_A and β_B) subunits protein in the equine fetal adrenal glands during mid to late gestation. Fetal adrenal glands of three equines were obtained at 217, 225 and 235 days of gestation. The sections of fetal adrenal glands were immunostained by the avidin-biotin-peroxidase complex method (ABC) using polyclonal antisera raised against porcine inhibin α, inhibin/activin β_A and inhibin/activin β_B. Inhibin/activin β_B was identified in cortex cells of fetal adrenal glands throughout 217-235 days of gestation, but inhibin α and inhibin/activin β_A were not observed in fetal adrenal glands in this period. These results suggest that equine fetal adrenal glands have the ability to synthesize activin B but not inhibins and activin A. Also, inhibin/activin β_B may play a regulatory role in developing equine fetal adrenal glands.