Evidence for the involvement of blood flow-related mechanisms in the ovulatory process of the rat

To elucidate whether any relationship exists between ovarian blood flow and ovulation rate, the effects on these parameters were examined in equine ch orionic gonadotrophin/human chorionic gonadotrophin (eCG/HCG) (151 U/151 U) primed rats after bilateral Ligation and severance of either the ovarian b ranch of the uterine artery and vein (UL), the ovarian artery and vein (OL) or both sites (UL+OL) in comparison to sham operations, Laser Doppler flow metry demonstrated the presence of microcirculatory vasomotion and a reduct ion of blood flow after UL, OL and UL+OL performed during the intervals 0-3 h (78, 66 and 19% of pretreatment values respectively) and 6-9 h (68, 57 a nd 20%) after HCG. Experiments utilizing radioactive microspheres also indi cated decreased ovarian blood how by UL and OL, Ovulation rate was assessed 20 h after HCG in animals where ligations had been performed at 0, 3, 6 an d 9 h after HCG. No ovulations were Seen after UL+OL and significantly decr eased ovulation rates (similar to 50% of sham operated animals) were seen a fter UL at 0 and 3 h and after OL at 0, 6 and 9 h, Progesterone concentrati ons in blood 20 h after HCG sere reduced by OL but not UL and ovarian weigh ts were unaffected by ligation, It is concluded that acute blood flow reduc tion during the ovulatory interval reduces ovulation rate in the rat.