Collagenolytic activity in the rabbit and sow Graafian follicle during ovulation

Abstract

At various intervals preceding ovulation sections of ovarian follicles were assayed for collagenolytic activity. Enzyme activity was estimated by ninhydrin colorimetric analysis which determined the amount of glycyl-prolyl-alanine (GPA) hydrolyzed from the synthetic substrate carbobenzoxy-glycyl-prolyl-glycyl-glycyl-prolyl-alanine. The enzyme concentration in tissue from rabbit follicles was 0.44 units 10 hr. before rupture, but decreased to 0.18 units at the time of ovulation. When follicular and stromal activities were determined in the same group of ovaries there was a reduction of 52% and 31%, respectively, as ovulation neared. At an estimated 20, 5, and 1 hr. before rupture of sow follicles the activity in homogenized theca externa and tunica albuginea was 0.13, 0.11, and 0.05 units, respectively. Simultaneously the activity in sow follicular fluid increased from 2.7 to 4.2, and finally to 5.6 units just before ovulation. The preovulatory decrease of collagenolytic activity in follicular tissue may reflect physiological labilization and subsequent dissipation from the follicle of the enzyme(s) determined by this procedure.