IMMUNOLOGICAL APPROACHES TO FERTILITY REGULATION IN DOMESTIC LIVESTOCK

Antibodies to hormones have been used extensively to study endocrine r egulation of reproduction and in recent times they have been commercia lly exploited as therapeutic agents to manipulate reproduction. Despit e the release of two commercial products, little is known about the me chanism of action of immunoneutralization. The presence of hormone-bin ding antibodies in the circulation and the detection of hormone antibo dy complexes in blood has led investigators to suggest a vascular site of action for immunoneutralization. However, a vascular site of actio n is difficult to reconcile with some of the known effects of immunone utralization to the boar taint steroid (5alpha-androst-16-en-3-one) to androstenedione and to gonadotrophin-releasing hormone. In this paper we review some of our recent research into the mechanism of action of androstenedione immunoneutralization. We suggest that hormonal immuno neutralization of androstenedione may take place in the extracellular. compartment or within the plasma membrane where antibodies to androste nedione may bind to a specific steroid-binding protein in the plasma m embrane of granulosa cells.