Vance Carrie K, King E Heath, Bowers Susan D, Ryan Peter L, Walters Kevin, Shappell Nancy W
Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Starkville, MS, United States.
Department of Pathobiology and Population Medicine, Mississippi State University, Starkville, MS, United States.
Front Vet Sci. 2019 Nov 26;6:423. doi: 10.3389/fvets.2019.00423. eCollection 2019.
It is known that zearalenone (ZON) interacts directly with estrogen receptors, and its effects on reproduction have been well-documented in several species. In contrast, reports of ZON's impact on horse reproduction are conflicting and inconclusive, some studies confounded by the presence of mycotoxins such as deoxynivalenol in the feed. This study assesses the effect of chronic consumption of zearalenone on reproduction in cycling mares fed >95% pure ZON (0, 2, or 8 mg/da; = 7 mares/treatment) for three estrous cycles, followed by artificial insemination, through 16 days of pregnancy. Animals were on ZON treatment for between 70 and 121 days (average 84) depending on individual cycle patterns. ZON-induced changes in serum concentration of estradiol (E) and progesterone (P), and total estrogenicity were measured using RIAs and the E-screen assay, respectively. Effects on reproductive physiology and pregnancy were monitored by ultrasound and clinical parameters. No significant changes were found in reproductive hormone levels of E, or P for mares on ZON treatments compared to controls, although there was a significant ( < 0.01) increase in P levels across Cycle number in High ZON (8 mg/da) treated mares. There was also an increasing trend in the interovulatory interval in the High ZON treatment group. The overall estrogenicity was similar across treatments and over time, not differing from controls or between ZON treatment groups. Adverse uterine and ovarian effects were also not observed, but pregnancy rates were mixed with only 4 of 7 mares on Low ZON becoming pregnant, and only 3 maintaining pregnancy and fetal heartbeat by Day 30, compared to 5 of 6 control mares and all 7 mares on High ZON. Because reproductive efficiency and hormone concentrations are highly variable across individuals, this study did not demonstrate that ZON at 2 or 8 mg/da was detrimental to mares' reproduction. Yet, inferring that ZON treatments were completely without effect is also not appropriate, as the absence of measurable significant differences could be attributed to the limited sample size. Most importantly, there were no extreme signs of toxicology, in contrast to previous reports when ZON was fed at these "doses."
已知玉米赤霉烯酮（ZON）可直接与雌激素受体相互作用，并且其对多种物种繁殖的影响已有充分记录。相比之下，关于ZON对马繁殖影响的报道相互矛盾且尚无定论，一些研究因饲料中存在脱氧雪腐镰刀菌烯醇等霉菌毒素而受到干扰。本研究评估了长期食用玉米赤霉烯酮对处于发情周期的母马繁殖的影响，这些母马被喂食纯度>95%的ZON（0、2或8毫克/天；每组7匹母马），持续三个发情周期，随后进行人工授精，并持续至妊娠16天。根据个体的周期模式，动物接受ZON治疗的时间为70至121天（平均84天）。分别使用放射免疫分析法（RIAs）和E-筛选试验测量ZON诱导的雌二醇（E）和孕酮（P）血清浓度变化以及总雌激素活性。通过超声和临床参数监测对生殖生理和妊娠的影响。与对照组相比，接受ZON治疗的母马的生殖激素E或P水平未发现显著变化，尽管在高剂量ZON（8毫克/天）治疗的母马中，整个周期内P水平有显著（P<0.01）升高。高剂量ZON治疗组的排卵间期也有增加趋势。各处理组之间以及随时间推移，总体雌激素活性相似，与对照组或ZON治疗组之间无差异。也未观察到子宫和卵巢的不良影响，但妊娠率参差不齐，低剂量ZON组的7匹母马中只有4匹怀孕，到第30天时只有3匹维持妊娠并检测到胎儿心跳，而对照组的6匹母马中有5匹怀孕，高剂量ZON组的7匹母马全部怀孕。由于个体之间的生殖效率和激素浓度差异很大，本研究未证明2毫克/天或8毫克/天的ZON对母马繁殖有害。然而，推断ZON治疗完全没有效果也是不合适的，因为未检测到显著差异可能归因于样本量有限。最重要的是，与之前以这些“剂量”喂食ZON的报道相比，没有出现极端的毒理学迹象。
