The miRNA target genes.

Objective
The aim of this study was to explore the differentially expressed miRNAs in the hearts of rats protected from early spontaneous hypertension by blood flow-restricted resistance training and to elucidate the effects of blood flow-restricted resistance training on the expression of these genes.
Methods
Four-week-old SHRs and WKY rats were used and randomly divided into five groups: the normal group (WKY), SHR control group (SHR-SED), high-intensity resistance training group (HIRT), medium-intensity resistance training group (MIRT), and blood flow-restricted medium-intensity resistance training group (BFRT). During the experiment, the body weight, cardiac function and hemodynamic parameters of the rats were measured. After training, total RNA was extracted from the left ventricular myocardium of rats in the SHR-SED group and the BFRT group, miRNAs were sequenced, followed by GO enrichment and KEGG pathway analyses, and the differentially expressed miRNAs were subsequently validated via qRT‒PCR.
Results
1) Hemodynamic tests revealed that the blood pressure of SHRs in the BFRT decreased significantly and that the blood pressure level of SHRs in the BFRT decreased more significantly than that of the simple resistance training groups did (P < 0.05). 2) Cardiac function tests revealed that the EF, FS, and MV E/A of SHRs in the BFRT significantly increased, whereas the HR, IVSd, IVSs, LVIDd, LIVDs, LVPWd, LVPWs and LV mass significantly decreased (P < 0.05). 3) Transcriptome sequencing revealed 9 differentially expressed miRNAs in the BFRT group compared with the SHR-SED group (2 miRNAs were significantly upregulated, and 7 miRNAs were significantly downregulated), with P < 0.05 and |log2FoldChange| ≥ 1 used as the criteria for differential significance. The most prominent differentially expressed miRNA was miR-200b-3p (P = 0.00, |log2FoldChange| = 2.45). 4) The miRNA validation results revealed that BFRT significantly reduced the expression of miR-200a-3p, miR-200b-3p, miR-342-3p, miR-350, miR-429, miR-1249, miR-1949 in SHR myocardium, and increased the expression of miR-31a-5p and miR-224-5p (P < 0.01).
Conclusion
Eight weeks of blood flow-restricted medium-intensity resistance training could lower SHR blood pressure, and it might also improve early SHR cardiac function by regulating the expression of miR-224-5p, miR-31a-5p, miR-200b-3p, miR-200a-3p, miR-342-3p, miR-429, miR-1949, miR-1249, and miR-350, with the differential expression of miR-200b-3p being particularly significant.

研究目的
本研究旨在探讨血流限制性阻力训练干预下，早期自发性高血压大鼠（Spontaneously Hypertensive Rats, SHR）心脏组织中差异表达的microRNAs (miRNAs)，并阐明该训练方式对这些基因表达的调控作用。

研究方法
选取4周龄的自发性高血压大鼠（SHR）及Wistar京都大鼠（Wistar Kyoto Rats, WKY），随机分为5组：正常组（WKY）、SHR对照组（SHR静坐组, SHR-SED）、高强度阻力训练组（High-Intensity Resistance Training, HIRT）、中强度阻力训练组（Medium-Intensity Resistance Training, MIRT）及血流限制性中强度阻力训练组（Blood Flow-Restricted Medium-Intensity Resistance Training, BFRT）。实验过程中，定期检测大鼠的体重、心功能及血流动力学参数。训练结束后，提取SHR对照组与BFRT组大鼠左心室心肌组织的总RNA，进行miRNA测序，随后开展基因本体（Gene Ontology, GO）富集分析与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路分析，并通过实时定量聚合酶链反应（quantitative real-time polymerase chain reaction, qRT-PCR）验证差异表达的miRNAs。

研究结果
1) 血流动力学检测结果显示，BFRT组SHR的血压显著降低，且其降压效果优于单纯阻力训练组（P<0.05）。
2) 心功能检测结果显示，BFRT组SHR的射血分数（EF）、短轴缩短率（FS）及二尖瓣口血流E/A比值（MV E/A）均显著升高，而心率（HR）、舒张期室间隔厚度（IVSd）、收缩期室间隔厚度（IVSs）、舒张期左心室内径（LVIDd）、收缩期左心室内径（LVIDs）、舒张期左室后壁厚度（LVPWd）、收缩期左室后壁厚度（LVPWs）及左心室质量（LV mass）均显著降低（P<0.05）。
3) 转录组测序结果显示，相较于SHR对照组，BFRT组共筛选出9个差异表达miRNAs，其中2个显著上调、7个显著下调，以P<0.05且|log₂折叠变化（log2FoldChange）|≥1作为差异显著性判定标准。差异最显著的miRNA为miR-200b-3p（P=0.00，|log2FoldChange|=2.45）。
4) miRNA验证结果显示，BFRT可显著下调SHR心肌组织中miR-200a-3p、miR-200b-3p、miR-342-3p、miR-350、miR-429、miR-1249、miR-1949的表达水平，并显著上调miR-31a-5p与miR-224-5p的表达（P<0.01）。

研究结论
八周的血流限制性中强度阻力训练可降低SHR的血压，同时可能通过调控miR-224-5p、miR-31a-5p、miR-200b-3p、miR-200a-3p、miR-342-3p、miR-429、miR-1949、miR-1249及miR-350的表达，改善早期自发性高血压大鼠的心功能，其中miR-200b-3p的差异表达尤为显著。