Bartlewski P M, Beard A P, Rawlings N C
Department of Veterinary Physiological Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
Theriogenology. 1999 Mar;51(4):813-27. doi: 10.1016/s0093-691x(99)00029-1.
The objective of this experiment was to assess the relationship between electrical resistance of the vaginal mucosa and serum concentrations of estradiol (E2) and progesterone (P4) during the estrous cycle in ewes. Vaginal impedance was recorded daily using a 2-electrode impedometer in 10 nonprolific Western white-faced and 7 prolific Finn ewes, during the mid-breeding season (October to December). Transrectal ultrasonography of ovaries was performed once a day to confirm ovulation and monitor follicle growth (follicles > or =3 mm in diameter) and development of corpora lutea (CL). Jugular blood samples were collected daily for radioimmunoassay (RIA) of estradiol and progesterone. In all ewes, a decline in vaginal impedance (to <40 ohms) was closely associated with the onset of behavioral estrus. In both breeds of sheep, there was no significant correlation between daily serum concentrations of estradiol and vaginal impedance throughout the estrous cycle. Daily serum concentrations of progesterone and the E2:P4 ratio were correlated with vaginal impedance during the period of luteolysis and follicular phase in both breeds (Western white-faced ewes: r = 0.62, P = 0.0002 and r = -0.56, P = 0.0002; Finn ewes: r = 0.61, P = 0.001 and r = -0.45, P = 0.03, respectively) and early in the cycle (Days 0 to 2, Day 0 = day of ovulation) in white-faced ewes (r = 0.61, P = 0.0003 and r = -0.36, P = 0.052, respectively) but not during the remaining portion of the luteal phase in either breed. In conclusion, vaginal mucous impedance appears to be primarily controlled by progesterone, but it also changes in response to shifts in the E2:P4 ratio when progesterone concentrations are low. Impedometric characteristics of the vaginal mucosa in cyclic ewes are an indicator of serum concentrations of progesterone and E2:P4 ratios during the terminal stage of the estrous cycle.
本实验的目的是评估母羊发情周期中阴道黏膜电阻与雌二醇（E2）和孕酮（P4）血清浓度之间的关系。在繁殖中期（10月至12月），使用两电极阻抗计每天记录10只非多产的西部白面母羊和7只多产的芬兰母羊的阴道阻抗。每天进行一次经直肠卵巢超声检查，以确认排卵并监测卵泡生长（直径≥3mm的卵泡）和黄体（CL）的发育。每天采集颈静脉血样，用于雌二醇和孕酮的放射免疫测定（RIA）。在所有母羊中，阴道阻抗下降（至<40欧姆）与行为发情的开始密切相关。在两个品种的绵羊中，整个发情周期中雌二醇的每日血清浓度与阴道阻抗之间均无显著相关性。在黄体溶解期和卵泡期，两个品种（西部白面母羊：r = 0.62，P = 0.0002和r = -0.56，P = 0.0002；芬兰母羊：r = 0.61，P = 0.001和r = -0.45，P = 0.03）以及白面母羊发情周期早期（第0至2天，第0天=排卵日）（分别为r = 0.61，P = 0.0003和r = -0.36，P = 0.052），孕酮的每日血清浓度和E2:P4比值与阴道阻抗相关，但在两个品种的黄体期其余阶段均不相关。总之，阴道黏膜阻抗似乎主要受孕酮控制，但当孕酮浓度较低时，它也会因E2:P4比值的变化而改变。周期性母羊阴道黏膜的阻抗特征是发情周期末期孕酮血清浓度和E2:P4比值的一个指标。
