[Tiaoqi electroacupuncture alleviates chronic pain-depression comorbidity via miRNA-124- mediated JAK2/STAT3...

To observe the effects of Tiaoqi (regulating qi) electroacupuncture (EA) on the micro ribonucleic acid-124 (miRNA-124) and Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in the prefrontal cortex (PFC) of rats with chronic pain-depression comorbidity (CPDC).

Sixty male SD rats were randomly divided into a blank group, a model group, an EA group and an EA+inhibitor group, with 15 rats in each group. Except for the blank group, the CPDC model was established by intraplantar injection of complete Freund's adjuvant in the other groups. Twenty-four hours after successful modeling, rats in the EA+inhibitor group received stereotaxic injection of miRNA-124 inhibitor into the PFC. Fourteen days after stereotaxic injection, Tiaoqi EA intervention was applied at bilateral "Hegu" (LI4) and "Taichong" (LR3) in the EA group and the EA+inhibitor group, with continuous wave, in frequency of 1.5 Hz, 20 min per time, once a day, for 14 consecutive days. Before modeling, after modeling and after intervention, mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were adopted to evaluate pain-like behaviors; open field test (OFT), sucrose preference test (SPT) and forced swimming test (FST) were performed to evaluate depression- like behaviors. After intervention, the expression of miRNA-124 in the PFC was detected by real-time quantitative PCR; the positive expression of JAK2, p-JAK2, STAT3 and p-STAT3 in the PFC was detected by immunohistochemistry; the levels of oxidative stress-related factors i.e. malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the PFC were detected by ELISA; the protein expression of apoptosis-related factors B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and cleaved cysteinyl aspartate specific proteinase-3 (Cleaved-Caspase-3) in the PFC was detected by Western blot; the neuronal apoptosis rate in the PFC was measured by TUNEL staining; the neuronal morphology in the PFC tissue was observed by HE staining.

Compared with the blank group, the MWT, TWL, sucrose preference rate, total movement distance and central residence time of OFT were decreased (P<0.05), the immobility time of FST was prolonged (P<0.05) in the model group. Compared with the model group, the MWT, TWL, sucrose preference rate, total movement distance and central residence time of OFT were increased (P<0.05), the immobility time of FST was shortened (P<0.05) in the EA group. Compared with the EA+inhibitor group, the MWT, TWL, sucrose preference rate, total movement distance and central residence time of OFT were increased (P<0.05), the immobility time of FST was shortened (P<0.05) in the EA group. Compared with the blank group, in the model group, the expression of miRNA-124, levels of SOD, CAT and GSH-Px, and protein expression of Bcl-2 in the PFC were decreased (P<0.05); the positive expression of p-JAK2 and p-STAT3, level of MDA, protein expression of Bax and Cleaved-Caspase-3, Bax/Bcl-2 ratio, and neuronal apoptosis rate were increased (P<0.05); the PFC neurons showed disordered arrangement, vacuoles and neurofibrillary tangles could be observed in the tissue interstitium, a large number of neurons exhibited pyknosis and hyperchromasia, and pyramidal cells were decreased or even disappeared. Compared with the model group, in the EA group, the expression of miRNA-124, levels of SOD, CAT and GSH-Px, and protein expression of Bcl-2 were increased in the PFC (P<0.05); the positive expression of p-JAK2 and p-STAT3, level of MDA, the protein expression of Bax and Cleaved-Caspase-3, Bax/Bcl-2 ratio and neuronal apoptosis rate were reduced (P<0.05); only a small number of pyknotic neurons were observed in the PFC tissue, with narrowed tissue interstitium and increased pyramidal cells. All the above indexes were improved in the EA group compared with those in the EA+inhibitor group.

Tiaoqi EA can effectively relieve CPDC by regulating the miRNA-124-mediated JAK2/STAT3 signaling pathway, alleviating oxidative stress and inhibiting neuronal apoptosis.