Oviductal isthmic motility in relation to ovulation and endocrine changes in unrestrained sows

This study was designed to characterize changes in the motility of the ovid uctal isthmus in relation to endocrine changes around ovulation in unrestra ined sows in their normal environment. Oviductal isthmic motility was monit ored on Polyview(TM) from 11 h prior to and up to 36 h after ovulation in 1 3 unrestrained multiparous sows during their second estrus after weaning, u sing a pressure microtransducer implanted 3 cm into the isthmus. Both the m aximum, minimum and mean pressures and the frequency of phasic pressure flu ctuations were high prior to ovulation but declined significantly (P<0.05) at 9 to 12 h, 13 to 16 h, 13 to 16 h and 5 to 8 h after ovulation, respecti vely. Plasma estradiol-17 beta and prostaglandin F-2 alpha, metabolite leve ls declined significantly (P<0.05) at 4 to 7 h prior to ovulation while pro gesterone levels increased significantly (P<0.01) at 5 to 8 h after ovulati on. The decrease in the plasma estradiol-17 beta levels was correlated to t he decrease in maximum and mean pressures and the frequency of phasic press ure fluctuations (n=113; r=0.30, 0.25, 0.25, respectively; P<0.01) but not to the decrease in minimum pressure (n=113; r=0.17, P>0.05). Similarly, the decrease in PGF(2 alpha) metabolite levels was correlated to the decrease in minimum, maximum and mean pressures and the frequency of phasic pressure fluctuations (n=112; r=0.43, 0.35, 0.38, 0.32, respectively; P<0.001). Con versely, the increase in plasma progesterone levels was correlated to the d ecrease in minimum, maximum and mean pressures and the frequency of phasic pressure fluctuations (n=113; r=-0.56, -0.70, -0.68, -0.60, respectively; P <0.001). Therefore, the pressure parameters seem to be influenced by change s in the levels of estradiol-17 beta, prostaglandin F-2 alpha and progester one with respect to ovulation. O 2000 by Elsevier Science Inc.