Vanselow Jens, Vernunft Andreas, Koczan Dirk, Spitschak Marion, Kuhla Björn
Institute of Reproductive Biology, Leibniz Institute for Farm Animal Biology (FBN), 18196 Dummerstorf, Germany.
Institute for Immunology, University of Rostock, 18055 Rostock, Germany.
PLoS One. 2016 Aug 17;11(8):e0160600. doi: 10.1371/journal.pone.0160600. eCollection 2016.
High environmental temperatures induce detrimental effects on various reproductive processes in cattle. According to the predicted global warming the number of days with unfavorable ambient temperatures will further increase. The objective of this study was to investigate effects of acute heat stress during the late pre-ovulatory phase on morphological, physiological and molecular parameters of dominant follicles in cycling cows during lactation. Eight German Holstein cows in established lactation were exposed to heat stress (28°C) or thermoneutral conditions (15°C) with pair-feeding for four days. After hormonal heat induction growth of the respective dominant follicles was monitored by ultrasonography for two days, then an ovulatory GnRH dose was given and follicular steroid hormones and granulosa cell-specific gene expression profiles were determined 23 hrs thereafter. The data showed that the pre-ovulatory growth of dominant follicles and the estradiol, but not the progesterone concentrations tended to be slightly affected. mRNA microarray and hierarchical cluster analysis revealed distinct expression profiles in granulosa cells derived from heat stressed compared to pair-fed animals. Among the 255 affected genes heatstress-, stress- or apoptosis associated genes were not present. But instead, we found up-regulation of genes essentially involved in G-protein coupled signaling pathways, extracellular matrix composition, and several members of the solute carrier family as well as up-regulation of FST encoding follistatin. In summary, the data of the present study show that acute pre-ovulatory heat stress can specifically alter gene expression profiles in granulosa cells, however without inducing stress related genes and pathways and suggestively can impair follicular growth due to affecting the activin-inhibin-follistatin system.
高温环境会对奶牛的各种生殖过程产生不利影响。根据全球变暖预测，环境温度不利的天数将进一步增加。本研究的目的是调查排卵前后期急性热应激对泌乳期发情周期奶牛优势卵泡的形态、生理和分子参数的影响。八头处于泌乳期的德国荷斯坦奶牛被暴露于热应激（28°C）或中性温度条件（15°C）下，并配对饲养四天。在激素诱导发情后，通过超声监测各自优势卵泡的生长两天，然后给予排卵剂量的促性腺激素释放激素（GnRH），并在23小时后测定卵泡类固醇激素和颗粒细胞特异性基因表达谱。数据显示，优势卵泡的排卵前生长以及雌二醇浓度有受到轻微影响的趋势，但孕酮浓度没有。mRNA微阵列和层次聚类分析显示，与配对饲养动物相比，热应激组颗粒细胞的基因表达谱明显不同。在255个受影响的基因中，不存在与热应激、应激或细胞凋亡相关的基因。相反，我们发现主要参与G蛋白偶联信号通路、细胞外基质组成的基因以及溶质载体家族的几个成员上调，同时编码卵泡抑素的FST基因也上调。总之，本研究数据表明，排卵前急性热应激可特异性改变颗粒细胞中的基因表达谱，但不会诱导与应激相关的基因和通路，并且可能由于影响激活素-抑制素-卵泡抑素系统而损害卵泡生长。
