Stanchev P D, Rodriguez-Martinez H, Albihn A, Eriksson H, Gustafsson H, Larsson K
Department of Anatomy and Histology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala.
Zentralbl Veterinarmed A. 1991 May;38(4):271-80. doi: 10.1111/j.1439-0442.1991.tb01013.x.
The present study aimed to correlate the repeat breeder syndrome in the bovine with an impaired or suboptimal uterine progestational response. Concentrations of nuclear (i.e. transformed) receptors for progesterone (PRn) were determined with a binding and exchange method in endometrial samples from virgin (VH) and repeat breeder (RBH) heifers 15 days post oestrus. The heifers were recipients of Day 7 demi-embryos collected from donors with normal fertility and transferred 8 days prior to tissue sampling. Results were compared with both the type of heifer, the condition of the embryo present within the uterus and the temporal relationship to the hormone plasma levels. The binding data for PRn indicated that a single class of high-affinity, low-capacity sites existed. The amount of PRn in VH endometria holding embryonic structures was significantly greater than in RBH, but no statistical differences were found in their plasma progesterone levels. PRn concentrations were also higher in the uterine horn in which an elongated (greater than 15 mm), morphologically normal embryo was present, when compared to cornua with small (less than 5 mm) embryos, regardless of recipient group. Furthermore, in endometria with an elongated embryo in the lumen, the relative amount of PRn was significantly greater in VH than in RBH. The present results indicate that the RBH recipients of Day 7 demi-embryos by Day 15 have fewer numbers of specific receptors for maternal progesterone, which could explain in part the poorer development of the transferred embryos compared with that in virgin heifers.
本研究旨在将牛的重复配种综合征与子宫孕激素反应受损或欠佳联系起来。在发情后15天，采用结合与交换法测定了未孕（VH）和重复配种（RBH）小母牛子宫内膜样本中孕激素核受体（即转化受体，PRn）的浓度。这些小母牛是从具有正常繁殖力的供体收集的第7天半胚胎的受体，并在组织取样前8天进行移植。将结果与小母牛的类型、子宫内存在的胚胎状况以及与激素血浆水平的时间关系进行了比较。PRn的结合数据表明存在一类单一的高亲和力、低容量位点。在怀有胚胎结构的VH子宫内膜中PRn的量显著高于RBH，但它们的血浆孕酮水平没有统计学差异。与存在小（小于5mm）胚胎的子宫角相比，在存在伸长（大于15mm）、形态正常胚胎的子宫角中，PRn浓度也更高，无论受体组如何。此外，在管腔中有伸长胚胎的子宫内膜中，VH中PRn的相对量显著高于RBH。目前的结果表明，到第15天时，接受第7天半胚胎的RBH受体中母体孕酮的特异性受体数量较少，这可以部分解释与未孕小母牛相比，移植胚胎发育较差的原因。
