A Vasoactive Intestinal Peptide Binding Component in Hen Granulosa Cells

Abstract

In radioligand assays, the vasoactive intestinal peptide (VIP) binding component in the membrane fraction of granulosa cells of the ovary of the hen was shown to possess characteristic properties of a receptor, such as reversible binding, binding specificity, high-affinity, and limited capacity. The binding site was of a single class. The binding affinity was higher in the largest (F₁) and the second largest follicle (F₂) than in the third largest follicle (F₃), and the binding capacity was greater in F₂ and F₃ than in F₁. During the ovulatory cycle, changes in affinity and capacity were observed only in F₁ shortly before ovulation. The results suggest the presence of VIP receptor in the hen granulosa cells and its binding is assumed to be related to the follicular growth and ovulation.