Effects of microRNA-490-5p on visceral sensitivity in rat with intestinal dysfunction

Abstract

Objective To investigate the role of microRNA-490-5p (miR-490-5p) in the regulation of visceral sensitivity in rats with intestinal dysfunction. Methods The lentivirus vector system was used to construct the rno-miRNA-490-5p lentivirus expression vector. The rats were divided into normal group, diarrhea-predominant irritable bowel syndrome (IBS-D) group, lentivirus empty vector group and the siRNA silent group and the latter three groups were model groups. The efficiency of siRNA was measured by real-time polymerase chain reaction (PCR). The rats were gavaged with 10% India ink, and then the time of first black stool, water content of feces and threshold of expansion capacity caused abdominal elevation or back arching were calculated. The visceral sensitivity of rats after miRNA-490-5p silenced was evaluated with abdominal withdrawal reflex (AWR) score by stimulating with different intensities of colonic dilatation. The abdominal electrical activity of rats stimulated by colonic distension was measured by BL-420F biological and functional experimental system. The change of the tension of rats isolated colon intestinal stimulated with acetylcholine chloride was also detected by BL-420F biological and functional experimental system. T test was used to compare the differences between the model groups and the normal group. One way analysis of variance was performed for multi-group comparison after miRNA-490-5p interfered. For comparison between two groups among multiple groups, least significant difference (LSD) method was used when the variance was equal, and Games-Howell method was used when the variance was unequal. Results The gastrointestinal propulsion time and the threshold of expansion capacity caused abdominal elevation or back arching of model groups were both lower than those of the normal group ((8.54±4.07) h vs (12.33±2.23) h, (0.56±0.08) mL vs (0.84±0.09) mL), and the differences were statistically significant (t=2.62 and 6.37, both P 0.05). After miRNA-490-5p silenced, gastrointestinal propulsion time of normal group, IBS-D group, lentivirus empty vector group and the siRNA silent group was (11.12±1.01) h, (6.23±3.17) h, (6.09±2.26) h and (12.36±1.97) h, and the differences among four groups were statistically significant (F=10.55, P 0.05). After distension with 1.6 mL sodium chloride solution, the abdominal electrical activity amplitude of silenced group was lower than the other groups, and the differences were statistically significant (F=11.09, P<0.01). After adding 1∶1 000 acetylcholine chloride added, the tension of colon of normal group, IBS-D group, lentivirus empty vector group and the siRNA silent group increased by 0.71±0.21, 0.81±0.06, 0.88±0.21 and 0.43±0.07, however there was no significant difference among the four groups (F=2.57, P=0.100). Conclusions Visceral hypersensitivity existed in rats with intestinal dysfunction. miRNA-490-5p may be involved in the regulation of visceral sensitivity. Key words: Irritable bowel syndrome; Visceral sensitivity; Abdominal electrical activities; Colonic tension; Rat