The comprehensive analysis of microRNA in hearts of stress model rat

Non-coding microRNAs (miRNAs) hold enormous potential as a postmortem biomarker to quantify the physical stress applied before the death. Excited delirium syndrome causes a sudden unexpected death under agitated and excited situation. The forensic autopsies and laboratory tests can't reveal the mechanism of the sudden death. Then, we constructed a rat model of excited delirium syndrome-like situation by applying three stress modalities, alcohol intake for 3.8 g/kg body weight, treadmill running for 90 min, and suppression by 2 kg water bag for 90 min. The rats were divided into three groups: the control, the stress group A with alcohol intake and running, and the stress group B with alcohol intake, running and suppression. After the rats were euthanized by sevoflurane over-dose, total RNA was extracted from 20 mg left ventricle tissues. The small RNA library and templates were prepared for the next generation sequencer (NGS) analysis with Ion PGM system and Ion 318Chip (Thermo Fisher Scientific). The obtained data were analyzed by Torrent Suite software with reference to the rat miRNA databases. The top 30 miRNAs in expression level were selected and analyzed by statistical methods between the control and stress groups. The seven miRNAs (miR-126a-3p, miR-143-3p, miR-16-5p, miR-22-3p, miR-26a-5p, miR-29a-3p, and miR-29b-3p) showed the significant difference in expression level among the groups. Especially, miR-143-3p and miR-22-3p might reflect the physical stress on rat hearts well.