Evidence for a Local Endothelin-Angiotensin-Atrial Natriuretic Peptide System in Bovine Mature Follicles In Vitro: Effects on Steroid Hormones

Recent evidence suggests the presence of a functional en-dothelin-angiotensin-atrial natriuretic peptide system at the ovarian level. This study aimed to investigate 1) the local inter-relationships among angiotensin II (Ang II), endothelin-1 (ET-1), and atrial natriuretic peptide (ANP); 2) the possible effect of each vasoactive peptide on the secretion of steroid hormones and prostaglandins (PGs) in isolated bovine mature follicles; and 3) the expression of mRNAs for Ang II, ET-1, and ANP receptors in the theca layer of follicles at different developmental stages. Each preovulatory follicle obtained before the LH surge (based on the concentrations of steroids and PGs) received im-plants of 4 capillary dialysis membranes into the theca layer. The follicles were then incubated in organ culture chambers and perfused with Ringer’s solution for 12 h. Stimulation by infusio