Changes in antiproteolytic activity in blood and ovarian follicular fluid in 3 breeds of sheep after stimulation of superovulation]

Serine proteases help to regulate the ovarian cycle at different levels and they are subjected to the control of gonadotropic hormones and protease inhibitors. Superovulation stimulations influence the activities of trypsin inhibitors (model serine protease) in blood plasma (BP) and in follicular fluid (FF), and also in dependence on the breed. Trypsin inhibiting activities were determined from the reduced rate of trypsin hydrolysis of a chromogenic substrate (TAPA) and they were determined in percent. A change in absorbancy at 405 nm = 1.0 after 10-minute incubation at 25 degrees C and pH = 8.05 was taken as 100%. The incubation mixture as a sample contained 100 microliters blood plasma or 10 microliters follicular fluid, diluted with gammaglobulin at 1:10. The differences in the trypsin inhibiting activities (TIA) of BP in ewes of the Merino, Tsigai and Wallachian breeds were insignificant, but Agelin synchronization (20 mg chlorsuperlutin per vaginal swab) induced statistically significant differences. The lowest TIA BP was recorded in the Tsigai breed (T), P less than 0.001 in comparison with the Wallachian (W) and Merino (M) breeds. Following the administration of 1,500 IU PMSG, the TIA BP within 120 hours decreased in W (P less than 0.001), it increased in T (P less than 0.1) and in M the changes in the TIA BP were insignificant. The average numbers of ovulations increased from 2.25 +/- 2.5 to 3.0 +/- 1.2 in W; from 0.25 +/- 0.43 to 2.5 +/- 1.6 in T and from 0.00 +/- 0.0 to 2.5 +/- 2.3 in M. Following the single administration of 2,000 IU PMSG after Agelin synchronization, the changes in M ewes were also insignificant, and there were no different responses in pregnant (1st to 2nd month) and nonpregnant ewes. In pregnant T ewes the TIA BP increased after Agelin synchronization and stimulation (P less than 0.01), in nonpregnant ewes these changes were not significant. In W lambing ewes the TIA BP increased (P less than 0.001), the effects of Agelin were greater than those of PMSG. The TIA of follicular fluid (FF) of antral follicles were on average tenfold if compared with BP. After hormonal treatment of ovaries, the TIA FF mostly increased at different levels of statistical significance. The TIA FF of follicles less than 10 mm were lower than in follicles greater than 10 mm (P less than 0.001 for M and W, P less than 0.1 for T).(ABSTRACT TRUNCATED AT 400 WORDS)