Area de Endocrinología, Facultad de Ciencias Veterinarias, UNCPBA, Campus Universitario, Paraje Arroyo Seco s/n, Tandil-7000, Buenos Aires, Argentina.
Acta Vet Scand. 2010 Feb 11;52(1):13. doi: 10.1186/1751-0147-52-13.
Llamas (Lama glama) are induced ovulators and the process of ovulation depends on dominant follicular size. In addition, a close relationship between behavioural estrus and ovulation is not registered in llamas. Therefore, the exogenous control of follicular development with hormones aims to predict the optimal time to mate. Oestradiol-17beta (E2) and its esters are currently used in domestic species, including camelids, in synchronization treatments. But, in llamas, there is no reports regarding the appropriate dosages to be used and most protocols have been designed by extrapolation from those recommended for other ruminants. The aim of the present study was to characterize plasma E2 concentrations in intact female llamas following a single intramuscular (i.m.) injection of two oestradiol esters: oestradiol benzoate (EB) and oestradiol cypionate (ECP).
Twelve non pregnant and non lactating sexually mature llamas were i.m. injected on day 0 with 2.5 mg of EB (EB group, n = 6) or ECP (ECP group, n = 6). Blood samples were collected immediately before injection, at 1, 6, 12, 24 h after treatment and then daily until day 14 post injection. Changes in hormone concentrations with time were analyzed in each group by analysis of variance (ANOVA) using a repeated measures (within-SS) design. Plasma E2 concentrations and area under the concentration-time curve (AUC) values were compared between groups by ANOVA. In all cases a Least-Significant Difference test (LSD) was used to determine differences between means. Hormonal and AUC data are expressed as mean +/- S.E.M.
Peak plasma E2 concentrations were achieved earlier and were higher in EB group than in ECP group. Thereafter, E2 returned to physiological concentrations earlier in EB group (day 5) than in ECP group (day 9). Although plasma E2 profiles differed over time among groups there were no differences between them on AUC values.
The i.m. injection of a single dose of both oestradiol esters resulted in plasma E2 concentrations exceeding physiological values for a variable period. Moreover, the plasma E2 profiles observed depended on the derivative of oestradiol administered. This basic information becomes relevant at defining treatment protocols including oestrogens in llamas.
羊驼是诱导排卵动物，排卵过程取决于优势卵泡的大小。此外，羊驼的性行为发情与排卵之间没有密切关系。因此，用激素对外源性控制卵泡发育的目的是预测最佳的交配时间。雌二醇-17β（E2）及其酯目前用于包括骆驼科动物在内的家畜同步处理。但是，在羊驼中，没有关于要使用的适当剂量的报告，并且大多数方案都是根据其他反刍动物推荐的方案推断出来的。本研究的目的是在单次肌肉内（i.m.）注射两种雌二醇酯（苯甲酸雌二醇（EB）和雌二醇环戊酯（ECP）后，描述完整雌性羊驼的血浆 E2 浓度特征。
12 只非妊娠和非哺乳期的性成熟羊驼在第 0 天接受 2.5 mg EB（EB 组，n = 6）或 ECP（ECP 组，n = 6）的 i.m.注射。在治疗前立即、治疗后 1、6、12、24 小时以及注射后第 14 天采集血样。使用重复测量（within-SS）设计的方差分析（ANOVA）分析每个组中随时间变化的激素浓度变化。通过 ANOVA 比较组间的激素浓度和曲线下面积（AUC）值。在所有情况下，都使用最小显著差异检验（LSD）来确定平均值之间的差异。激素和 AUC 数据表示为平均值 +/- S.E.M.
EB 组的血浆 E2 浓度峰值更早更高，并且 E2 恢复到生理浓度的时间也早于 ECP 组（第 5 天）。尽管两组之间的血浆 E2 谱随时间而有所不同，但 AUC 值之间没有差异。
单次肌肉内注射两种雌二醇酯均导致血浆 E2 浓度超过生理值，持续时间不同。此外，观察到的血浆 E2 谱取决于所给予的雌二醇衍生物。这一基本信息对于确定包括雌激素在内的羊驼治疗方案变得很重要。
