Towiboon Patcharapa, Saenphet Kanokporn, Tayapiwattana Chatchai, Tangyuenyong Siriwan, Watanabe Gen, Mahasawangkul Sittidet, Brown Janine L, Thitaram Chatchote
Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Center of Elephant and Wildlife Health, Chiang Mai University, Chiang Mai 50200, Thailand.
Vet Sci. 2022 May 22;9(5):244. doi: 10.3390/vetsci9050244.
The aim of this study was to examine relationships among serum progestagens, cortisol, and prolactin in pregnant and normal cycling Asian elephants living in tourist camps in northern Thailand. Samples were collected twice a month for 22 months from nine elephants. Of those, four were pregnant (24.3 ± 2.9 years of age; range 21−28 years) and five (20.2 ± 9.6 years; range 8−34 years) exhibited normal ovarian cycles based on serum progestagen analyses. Gestation was divided into three periods: 1st (week 1−31), 2nd (week 32−62), and 3rd (week 63 to parturition), while the estrous cycle was divided into the follicular and luteal phases. Serum progestagens were higher during the luteal phase of the cycle (p < 0.003), whereas cortisol and prolactin were similar. In pregnant elephants, there were no differences in serum progestagens or cortisol concentrations across the three gestational periods, whereas prolactin concentrations increased significantly during the 2nd and 3rd periods (p < 0.0001). By contrast, prolactin concentrations in nonpregnant elephants were consistently low throughout the ovarian cycle. In one cycling female, prolactin concentrations were similar to pregnant elephants, perhaps because she was an allomother to two calves. Another cycling female exhibited consistently elevated cortisol concentrations, 5 to 10 times higher than the other elephants. There were no correlations between serum progestagens, cortisol, and prolactin throughout gestation; however, serum progestagens and cortisol were positively related in cycling elephants (r = 0.386, p < 0.001). From our results, there were a number of individual differences in reproductive hormonal patterns, so it is important to develop personalized monitoring programs for each elephant to enhance breeding success and create sustaining captive populations of elephants in Asia.
本研究的目的是检测生活在泰国北部旅游营地的怀孕亚洲象和正常发情周期亚洲象的血清孕激素、皮质醇和催乳素之间的关系。在22个月的时间里，每月两次从9头大象身上采集样本。其中，4头怀孕（年龄24.3±2.9岁；范围21 - 28岁），另外5头（年龄20.2±9.6岁；范围8 - 34岁）根据血清孕激素分析显示具有正常的卵巢周期。妊娠期分为三个阶段：第1阶段（第1 - 31周）、第2阶段（第32 - 62周）和第3阶段（第63周直至分娩），而发情周期分为卵泡期和黄体期。血清孕激素在周期的黄体期较高（p < 0.003），而皮质醇和催乳素相似。在怀孕大象中，三个妊娠期的血清孕激素或皮质醇浓度没有差异，而催乳素浓度在第2和第3阶段显著增加（p < 0.0001）。相比之下，未怀孕大象的催乳素浓度在整个卵巢周期中一直较低。在一头处于发情周期的雌性大象中，催乳素浓度与怀孕大象相似，可能是因为它是两头幼象的代母。另一头处于发情周期的雌性大象的皮质醇浓度持续升高，比其他大象高5到10倍。在整个妊娠期，血清孕激素、皮质醇和催乳素之间没有相关性；然而，在发情周期的大象中，血清孕激素和皮质醇呈正相关（r = 0.386，p < 0.001）。根据我们的结果，生殖激素模式存在许多个体差异，因此为每头大象制定个性化的监测计划对于提高繁殖成功率和在亚洲建立可持续的圈养大象种群非常重要。
