Meyerholz Marie Margarete, Mense Kirsten, Linden Matthias, Raliou Mariam, Sandra Olivier, Schuberth Hans-Joachim, Hoedemaker Martina, Schmicke Marion
Endocrinology Laboratory, Clinic for Cattle, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, 30173, Hannover, Germany.
Institute for Farm Animal Reproduction, IFN Schönow e.V., Bernauer Allee 10, 16321, Bernau, Germany.
Acta Vet Scand. 2016 Sep 8;58(1):52. doi: 10.1186/s13028-016-0231-6.
Before the onset of fetal thyroid hormone production, the transplacental delivery of maternal thyroid hormones is necessary for embryonic and fetal development. Therefore, the adaptation of maternal thyroid hormone metabolism may be important for pregnancy success and embryo survival. The aims of this study were to determine the thyroid hormone levels during the early peri-implantation period until day 18 and on the day of ovulation, to determine whether pregnancy success is dependent on a "normothyroid status" and to determine whether physiological adaptations in maternal thyroid hormone metabolism occur, which may be necessary to provide sufficient amounts of biologically active T3 to support early pregnancy. Therefore, blood samples obtained on the day of ovulation (day 0) and days 14 and 18 of the Holstein-Friesian heifers (n = 10) during the respective pregnant, non-pregnant and negative control cycles were analyzed for thyroid-stimulating-hormone (TSH), thyroxine (T4) and triiodothyronine (T3). Liver biopsies (day 18) from pregnant and respective non-pregnant heifers were analyzed for mRNA expression of the most abundant hepatic thyroid hormone deiodinase (DIO1) by real time qPCR.
Although liver DIO1 mRNA expression did not differ between the pregnant and non-pregnant heifers on day 18, the serum concentrations of TSH and T3 on day 18 were higher in non-pregnant heifers compared to pregnant heifers (P < 0.05). Moreover, T3 decreased between day 0 and 18 in pregnant heifers (P < 0.001).
In conclusion, no associations between thyroid hormone patterns on day 18 and pregnancy success were detected. During the early peri-implantation period, TSH and T3 may be affected by the pregnancy status because both TSH and T3 were lower on day 18 in pregnant heifers compared to non-pregnant dairy heifers. In further studies, the thyroid hormone axis should be evaluated throughout the entire gestation to confirm these data and identify other possible effects of pregnancy on the thyroid hormone axis in cattle.
在胎儿甲状腺激素产生之前，母体甲状腺激素经胎盘输送对胚胎和胎儿发育至关重要。因此，母体甲状腺激素代谢的适应性变化可能对妊娠成功和胚胎存活具有重要意义。本研究的目的是测定从植入前期早期直至第18天以及排卵日的甲状腺激素水平，确定妊娠成功是否依赖于“甲状腺功能正常状态”，并确定母体甲状腺激素代谢是否发生生理适应性变化，这可能是为早期妊娠提供足够量生物活性T3所必需的。因此，对荷斯坦 - 弗里生小母牛（n = 10）在各自的妊娠、未妊娠和阴性对照周期中排卵日（第0天）、第14天和第18天采集的血样进行促甲状腺激素（TSH）、甲状腺素（T4）和三碘甲状腺原氨酸（T3）分析。通过实时定量PCR分析妊娠和相应未妊娠小母牛肝脏活检组织（第18天）中最丰富的肝脏甲状腺激素脱碘酶（DIO1）的mRNA表达。
虽然妊娠和未妊娠小母牛在第18天肝脏DIO1 mRNA表达无差异，但未妊娠小母牛第18天的血清TSH和T3浓度高于妊娠小母牛（P < 0.05）。此外，妊娠小母牛第0天至第18天T3水平下降（P < 0.001）。
总之，未检测到第18天甲状腺激素模式与妊娠成功之间的关联。在植入前期早期，TSH和T3可能受妊娠状态影响，因为与未妊娠奶牛相比，妊娠小母牛第18天的TSH和T3水平较低。在进一步研究中，应在整个妊娠期评估甲状腺激素轴，以证实这些数据并确定妊娠对牛甲状腺激素轴的其他可能影响。
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