Ovarian increase in kinin-generating capacity in PMSG/hCG-primed immature rat

Ovarian kinin-generating capacity was determined during induced ovulation in immature Wistar rats. The onset of ovulation was monitored by counting the number of ova in the oviducts at 2-h intervals after the administration of human chorionic gonadotropin (hCG). Ova began to appear in significant numbers at 14 h after hCG, with an average of 7.6 +/- 2.3 ova/rat. By 16 h after hCG, the oviducts contained 32.7 +/- 4.1 ova/rat. The ovaries from each group of animals were homogenized in phosphate-buffered saline, and extracts of this tissue were incubated for 200 min to allow the generation of kinins from endogenous kininogen. The amount of kinin generated by this procedure was measured by radioimmunoassay. At 0 h (i.e., just before the administration of hCG), the ovaries contained 5.90 +/- 0.60 pg kinin/micrograms protein per 200 min in the ovarian extract. By 4 h after hCG, the kinins increased significantly (P less than 0.05) to 13.16 +/- 3.61 pg kinin/micrograms protein. The kinins progressively increased (P less than 0.001) to 67.88 +/- 23.26 pg kinin/micrograms protein by 16 h after hCG. Indomethacin and cycloheximide significantly inhibited both kinin-generating activity and ovulation. These data suggest that kinin-forming activity and kinins may have a role in the ovulatory process of mammals.