Pelican K M, Brown J L, Wildt D E, Ottinger M A, Howard J G
Department of Reproductive Sciences, Conservation and Research Center, Smithsonian's National Zoological Park, Front Royal, VA 22630, USA.
Gen Comp Endocrinol. 2005 Nov;144(2):110-21. doi: 10.1016/j.ygcen.2005.04.014. Epub 2005 Jun 24.
Suppression and subsequent rebound of ovarian activity using a progestin (levonorgestrel; Norplant) versus a GnRH antagonist (antide) was assessed in the domestic cat via fecal estradiol and progesterone metabolite analyses. Following an initial dose-response trial, queens were assigned to one of four treatments: (1) antide, two 6 mg/kg injections 15 days apart (n = 8 cats); (2) levonorgestrel, six silastic rods (36 mg levonorgestrel/rod) implanted for 30 days (n = 8); (3) control injections (n = 5); and (4) control implants (n = 5). Steroid metabolites were quantified from daily fecal samples for 90 days before, 30 days during, and 90 days after treatment. Antide and levonorgestrel inhibited estrous cyclicity in contrast to continued cyclicity in controls. Cats already at estradiol baseline in antide (n = 7) and levonorgestrel (n = 4) groups remained inhibited during treatment. In females with elevated estradiol levels at treatment onset (Day 0), a normal estradiol surge was completed before concentrations declined to baseline (approximately Days 5-7) and remained suppressed throughout the remaining treatment period. Additionally, 56% of treatment animals exhibited at least one spontaneous ovulation during the pre-treatment period, but no female ovulated during treatment with levonorgestrel or antide. Antide-treated cats exhibited lower (P < 0.05) baseline estradiol concentrations during treatment compared to pre- and post-treatment. In contrast, levonorgestrel induced elevations in baseline estradiol following treatment compared to pre- and during treatment intervals. Control females showed no change (P > 0.05) in baseline estradiol throughout the study period. All levonorgestrel and antide cats returned to estrus after treatment withdrawal. Results demonstrate that: (1) both antide and levonorgestrel are effective for inducing short-term suppression of follicular recruitment and ovulation in the cat; (2) inhibition is reversible; and (3) GnRH antagonists and progestins differentially regulate basal estradiol secretion. This study also confirmed a relatively high incidence of spontaneous ovulation in the cat, a species generally considered to be an induced ovulator.
通过粪便雌二醇和孕酮代谢物分析，在家猫中评估了使用孕激素（左炔诺孕酮；Norplant）与促性腺激素释放激素（GnRH）拮抗剂（antide）抑制卵巢活动及随后的反弹情况。在初步剂量反应试验后，将母猫分为四种处理组之一：（1）antide组，每隔15天注射两次6 mg/kg（n = 8只猫）；（2）左炔诺孕酮组，植入6根硅橡胶棒（每根含36 mg左炔诺孕酮），持续30天（n = 8只）；（3）对照注射组（n = 5只）；（4）对照植入组（n = 5只）。在处理前90天、处理期间30天和处理后90天，对每日粪便样本中的类固醇代谢物进行定量分析。与对照组持续的发情周期不同，antide和左炔诺孕酮抑制了发情周期。antide组（n = 7只）和左炔诺孕酮组（n = 4只）中已处于雌二醇基线水平的猫在处理期间仍受到抑制。在处理开始时（第0天）雌二醇水平升高的雌性中，在浓度降至基线水平（约第5 - 7天）之前完成了正常的雌二醇激增，并且在整个剩余处理期间一直受到抑制。此外，56%的处理动物在处理前期至少有一次自发排卵，但在用左炔诺孕酮或antide处理期间没有雌性排卵。与处理前和处理后相比，接受antide处理的猫在处理期间的基线雌二醇浓度较低（P < 0.05）。相比之下，与处理前和处理期间相比，左炔诺孕酮处理后诱导基线雌二醇升高。在整个研究期间，对照雌性的基线雌二醇没有变化（P > 0.05）。所有左炔诺孕酮和antide处理的猫在停药后都恢复了发情。结果表明：（1）antide和左炔诺孕酮都能有效诱导短期抑制猫的卵泡募集和排卵；（2）抑制是可逆的；（3）GnRH拮抗剂和孕激素对基础雌二醇分泌的调节不同。本研究还证实了猫中自发排卵的发生率相对较高，而猫通常被认为是诱导排卵动物。
