δ-Opioid Receptor Activation Modified MicroRNA Expression in the Rat Kidney under Prolonged Hypoxia

Abstract

Hypoxic/ischemic injury to kidney is a frequently encountered clinical problem with limited therapeutic options. Since microRNAs are differentially involved in hypoxic/ischemic events and δ-opioid receptor (DOR) activation is known to protect against hypoxic/ischemic injury, we speculated on the involvement of DOR activation in altering the microRNA (miRNA) expression in kidney under hypoxic condition. We selected 31 miRNAs based on microarray data for quantitative PCR analysis. Among them, 14 miRNAs were significantly altered after prolonged hypoxia, DOR activation or a combination of both. We found that 1) DOR activation alters miRNA expression profiles in normoxic conditions; 2) hypoxia differentially alters miRNA expression depending on the duration of hypoxia; and 3) DOR activation can modify hypoxia-induced changes in miRNA expression. For example, 10-day hypoxia reduced the level of miR-212 by over 70%, while DOR activation could mimic such reduction even in normoxic kidney. In contrast, the same stress increased miR-29a by >100%, which was reversed following DOR activation. These first data suggest that hypoxia comprehensively modifies the miRNA profile within the kidney, which can be mimicked or modified by DOR activation. Ascertaining the targeted pathways that regulate the diverse cellular and molecular functions of miRNA may provide new insights into potential therapies for hypoxic/ischemic injury of the kidney.

δ-Opioid Receptor Activation and MicroRNA Expression in the Rat Heart Under Prolonged Hypoxia

“…There are also other studies showing that DOR agonists can prolong survival of peripheral organs, such as the lungs, heart, liver, and kidney, and that DOR activation is protective against hypoxic/ischemic injury in the heart [22,23]. Since there is a growing body of evidence indicating that miRNAs play several regulatory roles in opioid pharmacology [24,25], and our previous studies demonstrate the involvement of DOR in the regulation of miRNA expression in the brain and kidney [26,27], we wanted to know whether DOR affects miRNA expression in the heart when exposed to prolonged hypoxia.…”

“…The total RNA was extracted from the collected homogenate using TRIzol Reagent (Thermo Fisher, USA) according to the manufacturer's instructions. The miRNA expression levels were quantified using TaqMan microRNA assay (Thermo Fisher, USA) on the Applied Biosystems 7500 (Thermo Fisher, USA) as previously reported [27]. U6 served as an internal control.…”

Characteristic MicroRNA Expression Induced by δ-Opioid Receptor Activation in the Rat Liver Under Prolonged Hypoxia

“…We monitored hypoxia-induced changes in the liver and body weights and investigated 20 miRNAs (miR-7a-5p, miR-10a-5p, miR-25-3p, miR-26b-5p, miR-30e-5p, miR-34a-5p, miR-34c-5p, miR-107-3p, miR-122-5p, miR-125a-5p, miR-128a-3p, miR-135b-5p, miR-142-5p, miR-145-5p, miR-146a-5p, miR-181a-5p, miR-182, miR-184, miR-192-5p, and miR-204-5p) that differentially respond to hypoxic stress based on our microarray and PCR analyses of miRNAs in the hypoxic kidney [26], cortex [25], and heart [27]. …”

“…The total RNA was extracted from the collected homogenate using TRIzol Reagent (Thermo Fisher, USA) according to the manufacturer’s instructions. The miRNA expression levels were quantified using TaqMan microRNA assay (Thermo Fisher, USA) on the Applied Biosystems 7500 (Thermo Fisher, USA) as previously reported [26]. U6 served as an internal control.…”

Effect of δ-Opioid Receptor Activation on BDNF-TrkB vs. TNF-α in the Mouse Cortex Exposed to Prolonged Hypoxia

“…Immediately before use, the stock solution was diluted in saline to the expected concentrations. The doses of UFP-512 was 1 mg/kg based on the previous works [47,48]. …”