Anhui Provincial Key Laboratory of Conservation and Germplasm Innovation of Local Livestock, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China.
Qinghai Provincial Key Laboratory of Adaptive Management on Alpine Grassland, Qinghai Academy of Animal Science and Veterinary Medicine, Qinghai University, Xining 810016, China.
Int J Mol Sci. 2024 Oct 17;25(20):11161. doi: 10.3390/ijms252011161.
Heat stress (HS) has become a common stressor, owing to the increasing frequency of extreme high-temperature weather triggered by global warming, which has seriously affected the reproductive capacity of important livestock such as sheep. However, little is known about whether HS reduces sperm motility by inducing circadian rhythm disorders in rumen microorganisms and metabolites in sheep. In this study, the year-round reproduction of two-year-old Hu rams was selected, and the samples were collected in May and July 2022 at average environmental temperatures between 18.71 °C and 33.58 °C, respectively. The experiment revealed that the mean temperature-humidity index was 86.34 in July, indicating that Hu rams suffered from HS. Our research revealed that HS significantly decreased sperm motility in Hu rams. Microbiome analysis further revealed that HS reshaped the composition and circadian rhythm of rumen microorganisms, leading to the circadian disruption of microorganisms that drive cortisol and testosterone synthesis. Serum indicators further confirmed that HS significantly increased the concentrations of cortisol during the daytime and decreased the testosterone concentration at the highest body temperature. Untargeted metabolomics analysis revealed that the circadian rhythm of rumen fluid metabolites in the HS group was enriched by the cortisol and steroid synthesis pathways. Moreover, HS downregulated metabolites, such as kaempferol and L-tryptophan in rumen fluid and seminal plasma, which are associated with promotion of spermatogenesis and sperm motility; furthermore, these metabolites were found to be strongly positively correlated with . Overall, this study revealed the relationship between the HS-induced circadian rhythm disruption of rumen microorganisms and metabolites and sperm motility decline. Our findings provide a new perspective for further interventions in enhancing sheep sperm motility with regard to the circadian time scale.
热应激（HS）已成为一种常见的应激源，由于全球变暖导致极端高温天气的频率增加，这严重影响了绵羊等重要家畜的繁殖能力。然而，目前尚不清楚 HS 是否通过诱导瘤胃微生物和代谢物的昼夜节律紊乱来降低绵羊的精子活力。在这项研究中，选择了两岁的湖羊进行全年繁殖，并于 2022 年 5 月和 7 月分别在平均环境温度为 18.71°C 和 33.58°C 时采集样本。实验表明，7 月的平均温湿度指数为 86.34，表明湖羊遭受了热应激。我们的研究表明，热应激显著降低了湖羊的精子活力。微生物组分析进一步揭示了热应激重塑了瘤胃微生物的组成和昼夜节律，导致了驱动皮质醇和睾酮合成的微生物的昼夜节律紊乱。血清指标进一步证实，热应激显著增加了白天皮质醇的浓度，并在体温最高时降低了睾酮浓度。非靶向代谢组学分析表明，HS 组瘤胃液代谢物的昼夜节律通过皮质醇和类固醇合成途径得到了富集。此外，热应激下调了瘤胃液和精液中与促进精子发生和精子活力相关的代谢物，如 kaempferol 和 L-色氨酸；并且这些代谢物与. 呈强烈正相关。总的来说，这项研究揭示了 HS 诱导的瘤胃微生物和代谢物昼夜节律紊乱与精子活力下降之间的关系。我们的研究结果为在昼夜节律时间尺度上进一步干预提高绵羊精子活力提供了新的视角。
