Sayre B L, Lewis G S
Department of Animal and Poultry Sciences Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0306, USA.
Theriogenology. 1997 Jul 15;48(2):267-75. doi: 10.1016/s0093-691x(97)84074-5.
Based on our previous work, we found that exogenous oxytocin induces uterine tetany and cervical dilation, and permits transcervical access to the uterus. However, the oxytocin does not reduce sustained sperm transport from the uterus to the oviducts. Thus, we hypothesized that exogenous oxytocin may be a useful adjunct to transcervical intrauterine AI procedures for sheep: two experiments were conducted to test our hypothesis. In Experiment 1, purebred ewes (n = 75/group) were artificially inseminated intrauterine with either laparoscopic or oxytocin-transcervical (i.e., 200 USP units of oxytocin 30 min before AI) procedures. At 54 h after progestogenated pessaries were removed, ewes were inseminated with 200 x 10(6) sperm/0.25 ml of fresh, extended semen, which was collected from a purebred ram of the corresponding breed. Pregnancy rate was greater (P < 0.05) after laparoscopic (37.5%) than after transcervical AI (0%). Because of the disappointing results of Experiment 1, Experiment 2 was conducted to determine whether oxytocin or the AI procedure per se reduced ovum fertilization rate. Treatments were designed in a 2 x 2 factorial arrangement. At 60 h after norgestomet implant removal and 10 min before either laparoscopic or transcervical (cervical in a saline group) AI with 100 x 10(6) sperm/0.25 ml, ewes (n = 10/group) received an intravenous injection of either isotonic saline or 200 USP units of oxytocin. Fertilization rate, which was determined 72 h after AI, was greater (P < 0.05) after laparoscopic than after transcervical/cervical AI (92.5 vs 28%), but oxytocin treatment did not affect fertilization rate. The results indicate that exogenous oxytocin did not reduce ovum fertilization rate, but the transcervical AI procedure per se seemed to reduce fertilization rate.
基于我们之前的研究工作，我们发现外源性催产素可诱发子宫强直性收缩和宫颈扩张，并允许经宫颈进入子宫。然而，催产素并不能减少精子从子宫持续运输至输卵管。因此，我们推测外源性催产素可能是绵羊经宫颈子宫内人工授精（AI）操作的一种有用辅助手段：进行了两项实验来验证我们的假设。在实验1中，纯种母羊（每组n = 75只）通过腹腔镜或催产素经宫颈（即在人工授精前30分钟注射200美国药典单位催产素）的方法进行子宫内人工授精。在取出含孕激素的阴道栓54小时后，母羊用从相应品种的纯种公羊采集的200×10⁶个精子/0.25毫升新鲜稀释精液进行授精。腹腔镜人工授精后的妊娠率（37.5%）高于经宫颈人工授精后的妊娠率（0%）（P < 0.05）。由于实验1的结果令人失望，进行了实验2以确定是催产素还是人工授精操作本身降低了卵子受精率。实验处理采用2×2析因设计。在取出诺孕美特植入物60小时后，且在进行腹腔镜或经宫颈（生理盐水组为宫颈注射）人工授精（100×10⁶个精子/0.25毫升）前10分钟，母羊（每组n = 10只）静脉注射等渗盐水或200美国药典单位催产素。人工授精72小时后测定的受精率，腹腔镜人工授精后的受精率高于经宫颈/宫颈人工授精后的受精率（92.5%对28%，P < 0.05），但催产素处理对受精率没有影响。结果表明，外源性催产素并未降低卵子受精率，但经宫颈人工授精操作本身似乎降低了受精率。
