Morfeld Kari A, Ball Ray L, Brown Janine L
J Zoo Wildl Med. 2014 Sep;45(3):569-76. doi: 10.1638/2013-0254R.1.
Hyperprolactinemia is associated with reproductive acyclicity in zoo African elephants (Loxodonta africana) and may contribute to the non-self-sustainability of the captive population in North America. It is a common cause of infertility in women and other mammals and can be treated with the dopamine agonist cabergoline. The objectives of this study were to assess prolactin responses to cabergoline treatment in hyperprolactinemic, acyclic African elephants and to determine the subsequent impact on ovarian cyclic activity. Five elephants, diagnosed as hyperprolactinemic (>11 ng/ml prolactin) and acyclic (maintenance of baseline progestagens for at least 1 yr), were treated with 1-2 mg cabergoline orally twice weekly for 16-82 wk. Cabergoline reduced (P < 0.05) serum prolactin concentrations during the treatment period compared to pretreatment levels in four of five elephants (11.5 +/- 3.2 vs. 9.1 +/- 3.4 ng/ml; 20.3 +/- 16.7 vs. 7.9 +/- 9.8 ng/ml; 26.4 +/- 15.0 vs. 6.8 +/- 1.5 ng/ml; 42.2 +/- 22.6 vs. 18.6 +/- 8.9 ng/ml). However, none of the females resumed ovarian cyclicity based on serum progestagen analyses up to 1 yr posttreatment. In addition, within 1 to 6 wk after cessation of oral cabergoline, serum prolactin concentrations returned to concentrations that were as high as or higher than before treatment (P < 0.05). One elephant that exhibited the highest pretreatment prolactin concentration (75.2 +/- 10.5 ng/ml) did not respond to cabergoline and maintained elevated levels throughout the study. Thus, oral cabergoline administration reduced prolactin concentrations in elephants with hyperprolactinemia, but there was no resumption of ovarian cyclicity, and a significant prolactin rebound effect was observed. It is possible that higher doses or longer treatment intervals may be required for cabergoline treatment to result in permanent suppression of prolactin secretion and to mitigate associated ovarian cycle problems.
高催乳素血症与圈养非洲象（Loxodonta africana）的生殖无周期性有关，可能是导致北美圈养象种群无法自我维持的一个原因。它是女性和其他哺乳动物不孕的常见原因，可用多巴胺激动剂卡麦角林进行治疗。本研究的目的是评估卡麦角林治疗对高催乳素血症、无周期性的非洲象催乳素的反应，并确定其对卵巢周期性活动的后续影响。五头被诊断为高催乳素血症（催乳素>11 ng/ml）且无周期性（基线孕激素维持至少1年）的大象，每周口服1 - 2 mg卡麦角林两次，持续16 - 82周。与五头大象中四头的治疗前水平相比，卡麦角林在治疗期间降低了（P < 0.05）血清催乳素浓度（11.5±3.2 vs. 9.1±3.4 ng/ml；20.3±16.7 vs. 7.9±9.8 ng/ml；26.4±15.0 vs. 6.8±1.5 ng/ml；42.2±22.6 vs. 18.6±8.9 ng/ml）。然而，根据血清孕激素分析，直至治疗后1年，没有一头雌性恢复卵巢周期性。此外，在口服卡麦角林停止后的1至6周内，血清催乳素浓度恢复到与治疗前一样高或更高的水平（P < 0.05）。一头治疗前催乳素浓度最高（75.2±10.5 ng/ml）的大象对卡麦角林无反应，在整个研究过程中催乳素水平一直居高不下。因此，口服卡麦角林可降低高催乳素血症大象的催乳素浓度，但卵巢周期性并未恢复，且观察到明显的催乳素反弹效应。可能需要更高剂量或更长的治疗间隔，卡麦角林治疗才能永久性抑制催乳素分泌并缓解相关的卵巢周期问题。
