Kinder J E, Garcia-Winder M, Imakawa K, Day M L, Zalesky D D, D'Occhio M L, Stumpf T T, Kittok R J, Schanbacher B D
Department of Animal Science, University of Nebraska, Lincoln 68583.
Domest Anim Endocrinol. 1991 Oct;8(4):463-9. doi: 10.1016/0739-7240(91)90015-c.
The objective of the research was to determine the relationship between circulating 17 beta-estradiol (E2) and secretion of luteinizing hormone (LH) in cows. A second objective was to determine if response to E2 was influenced by interval between ovariectomy and the start of E2 treatment. Thirty-one nulliparous cows 3 yr of age were randomly assigned to a 2 x 4 factorial arrangement of treatments. Sixteen cows were ovariectomized at 18 mo of age (long term), and the other 15 cows were ovariectomized at 36 mo of age (short term). At the time of ovariectomy of cows in the short term group, 11 cows in the short term group and 12 cows in the long term group were implanted subcutaneously with 1, 2 or 4 polydimethylsiloxane capsules containing E2. The other eight cows served as non-implanted controls (n = 4-short term, n = 4-long term). All cows were fitted with jugular vein catheters on day 29 of treatment, and on day 30 blood samples were collected at 12-min intervals for 6 hr. At the end of 6 hr, luteinizing hormone-releasing hormone (LHRH) was administered and blood sampling continued at 12-min intervals for an additional hour. Serum was analyzed for LH and E2. Variables of LH secretion analyzed were mean concentration, frequency of pulses, amplitude of pulses and maximum concentration after LHRH. There were no significant interactions for any of the variables of LH among cows ovariectomized for the long and short term. There was a significant linear increase in mean concentration of LH with increased circulating concentration of E2.(ABSTRACT TRUNCATED AT 250 WORDS)
该研究的目的是确定奶牛体内循环的17β-雌二醇（E2）与促黄体生成素（LH）分泌之间的关系。另一个目的是确定E2反应是否受卵巢切除与E2治疗开始之间的间隔影响。将31头3岁未产奶牛随机分配到2×4析因处理组。16头奶牛在18月龄时进行卵巢切除（长期组），另外15头奶牛在36月龄时进行卵巢切除（短期组）。在短期组奶牛进行卵巢切除时，短期组的11头奶牛和长期组的12头奶牛皮下植入含E2的1、2或4个聚二甲基硅氧烷胶囊。另外8头奶牛作为未植入对照组（短期组4头，长期组4头）。在治疗第29天，所有奶牛均安装颈静脉导管，在第30天，每隔12分钟采集一次血样，共采集6小时。6小时结束时，注射促黄体生成素释放激素（LHRH），并继续每隔12分钟采集一次血样，持续1小时。分析血清中的LH和E2。分析的LH分泌变量包括平均浓度、脉冲频率、脉冲幅度以及LHRH后的最大浓度。长期和短期卵巢切除的奶牛之间，LH的任何变量均无显著交互作用。随着循环中E2浓度的增加，LH的平均浓度呈显著线性增加。（摘要截短于250词）
