[Changes in antiproteolytic activity in the blood and cervical mucus after superovulation stimulation]

The function of proteins, peptides, proteases and inhibitors of proteases in modulations of regulation mechanisms of gonadotrophins during the development of ovarian folicles has not been fully explained up to now. We can see difference reactions of ewes to superovulation stimulations in oestrous and anoestrous periods as shown by the variation of the antiproteolytic activity of blood plasma and cervical mucus. Trypsin is used as a model for serine protease, and trypsin inhibitory activity (TIA) was measured from the reduced rate of trypsin hydrolysis of the chromogenic substrate N-alpha-tosyl-L-arginine-4-nitroanilide (TAPA, Bartík et al., 1974). Full hydrolytic activity was determined as a change in absorbency at 405 nm = 1.0 after ten-minute incubation at 25 degrees C and pH = 8.1, and inhibition was expressed in percentage of full activity. Statistical analyses were performed by Student's t-test. Twenty-three ewes in anoestrus and twenty-eight ewes in oestrus were included in this experiment. They were of the Slovak Merino breed, two to three years old, with the mean live weight of thirty to forty kg. The ewes were treated with Ageline vaginal sponges (20 mg chlorsuperlutin/sponge) to provide for synchronization of ovarian activity, in the interval of eleven to twelve days. After removal of sponges, the ewes were stimulated for superovulation as shown in Tab. I. Heparinized blood plasma samples were stored at -25 degrees C. Low molecular TIA activities were determined in HClO4--treated blood plasma. Samples of cervical mucus were taken on cotton-wool tampons which were evaluated in 0.2 M Tris-HCl buffer, pH = 8.1. Figs. 1-6 shows TIA changes in blood plasma and cervical mucus on particular days. Fig. 7 shows the mean values of controls (I-initial) after synchronization (A) and after stimulation (S). TIA changes were different in anoestrous and oestrous periods. Differences in TIA changes in blood plasma and cervical mucus in oestrous period suggested certain local regulation mechanisms of synthesis and/or secretion of this activity in the cervix. Some values of TIA were maximum at the time of expected heat or ovulation and may be some of the factor(s) which influenced fertility of females after superovulation stimulations.