de Souza C J, Campbell B K, Baird D T
Department of Obstetrics and Gynaecology, University of Edinburgh, Centre for Reproductive Biology, UK.
Hum Reprod. 1998 Nov;13(11):3016-22. doi: 10.1093/humrep/13.11.3016.
In women there is a gradual rise in the basal level of follicle stimulating hormone (FSH) in the years prior to the menopause (pre-menopause) which is thought to be due to a relative lack of ovarian factors reflecting the number of antral follicles present in the ovaries. Experimental animal models for this phenomenon, particularly in mono-ovulatory species, have been lacking due to most animals' relatively short life span. We have available a group of experimental ewes in which the right ovary was removed and the left ovary was autotransplanted to the neck at least 10 years previously, which have been maintained in good health until an age of 12-13 years. Two experiments were conducted with these animals to determine the endocrine and follicular effects of age: a retrospective experiment in the same Finn-Merino ewes (n = 5) when the animals were 6-7 or 12-13 years of age; and a cohort experiment in old (12-13 years, n = 6) and young (2 years, n = 5) ewes of the same breed. In both retrospective and cohort experiments, the concentrations of FSH were significantly higher (P < 0.05) in older animals during the luteal phase when oestradiol secretion was low. This increase in FSH was associated with a decrease in the concentration of inhibin A (P < 0.05) in older animals in both the follicular and luteal stages of the cycle but the concentrations of oestradiol were similar between ages. Although there were significantly fewer antral follicles (P < 0.05) available for development in older ewes during the early luteal phase of the cycle, the ovulation rate was similar to that observed in younger animals (2.0+/-0 vs 2.0+/-4; P > 0.05) but the interval from luteal regression to the onset of the LH surge was longer (P < 0.05) in older animals. In conclusion, the endocrine changes associated with increasing reproductive age in sheep are therefore similar to those observed in women, suggesting that the sheep could be a useful animal model to study the effect of age on human fertility.
在绝经前的数年（绝经前期），女性促卵泡激素（FSH）的基础水平会逐渐升高，这被认为是由于反映卵巢中窦卵泡数量的卵巢因子相对缺乏所致。由于大多数动物的寿命相对较短，一直缺乏针对这一现象的实验动物模型，尤其是单排卵物种的模型。我们有一组实验母羊，其右侧卵巢在至少10年前被切除，左侧卵巢自体移植到颈部，这些母羊一直保持健康，直至12 - 13岁。对这些动物进行了两项实验，以确定年龄对内分泌和卵泡的影响：一项回顾性实验，对象为同一批芬兰美利奴母羊（n = 5），分别在6 - 7岁和12 - 13岁时进行；另一项队列实验，对象为同一品种的老年（12 - 13岁，n = 6）和幼年（2岁，n = 5）母羊。在回顾性实验和队列实验中，在黄体期雌二醇分泌较低时，老年动物体内FSH的浓度均显著更高（P < 0.05）。FSH的这种升高与老年动物在卵泡期和黄体期抑制素A浓度的降低相关（P < 0.05），但不同年龄组之间雌二醇的浓度相似。尽管在周期的早期黄体期，老年母羊中可供发育的窦卵泡数量显著减少（P < 0.05），但其排卵率与幼年动物相似（2.0±0对2.0±4；P > 0.05），但老年动物从黄体退化到促黄体生成素高峰开始的间隔时间更长（P < 0.05）。总之，绵羊中与生殖年龄增加相关的内分泌变化与女性中观察到的相似，这表明绵羊可能是研究年龄对人类生育能力影响的有用动物模型。
