[Swertiamarin alleviates diabetic peripheral neuropathy in rats by suppressing NOXS/ ROS/NLRP3 signal pathway]

OBJECTIVE

To observe the therapeutic effect of swertiamarin on diabetic peripheral neuropathy (DPN) in rats and explore the molecular mechanism in light of the NOXS/ROS/NLRP3 signal pathway.

OBJECTIVE

Thirty-two SD rats were randomly divided into control group, DPN model group (treated with saline), swertiamarin (5 mg/kg) treatment group and NOXS inhibitor (10 mL/kg DPI) treatment group. Rat models of DPN were established in the latter 3 groups by intraperitoneal injections of STZ, and the treatments were administered on days 1, 7 and 14 after modeling. Tactile hypersensitivity of the rats was evaluated 30 min after the treatment. The expressions of NOXS, ROS, NLRP3 and inflammatory factors in the spinal cord tissue were detected using ELISA, and the protein expressions of NOXS, ROS, and NLRP3 were also detected with Western blotting.

OBJECTIVE

Compared with those in the control group, the rats in DPN group showed significant hyperalgesia (P < 0.001), increased expressions of TNF-α (P < 0.001) and IL-6 (P < 0.001), decreased expressions of TGF-β (P < 0.001), and increased expressions of NOXS/ROS/NLRP3 signal pathway (P < 0.001). Compared with those in DPN model group, the rats with swertiamarin treatment showed improved hyperalgesia (P < 0.001), decreased expressions of TNF-α (P=0.03) and IL-6 (P=0.002), increased expressions of TGF-β (P=0.04), and decreased expressions of NOXS (P < 0.001), ROS (P < 0.001) and NLRP3 (P=0.002). Treatment with swertiamarin and the NOXS inhibitor produced similar effects on the expressions of the inflammatory factors in the rat models (P>0.05).

OBJECTIVE

DPN effectively relieves hyperalgesia in rat models of DPN by restoring the balance in the expressions of the inflammatory factors by suppressing NOXs/ROS/NLRP3 signaling pathway.

Investigation of the role of miR-221 in diabetic peripheral neuropathy and related molecular mechanisms

BACKGROUND

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes, but the molecular mechanisms of DPN are still unclear.

OBJECTIVES

To investigate the role of miR-221 in DPN and the related molecular mechanisms.

MATERIAL AND METHODS

Streptozotocin (STZ) was used to establish an in vivo DPN model. An in vitro DPN model was established using high glucose-induced SH-SY5Y cells. The pain condition of rats was measured by evaluating the 50% paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). Serum exosomes were extracted and identified. Expression of miR-221 in serum exosomes and serum SOCS3 expression were determined using reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Western blotting was used to measure the protein levels of SOCS3, bradykinin (BK) and prostaglandin E2 (PEG2). The dual luciferase reporter assay was performed to confirm SOCS3 3'-UTR as a target of miR-221. The serum or cell supernatant levels of PEG2, BK, interleukin (IL)-6, IL-1β, and tumor necrosis factor alpha (TNF-α) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Induction of the lenti-miR-221 inhibitor significantly decreased the expression of miR-221 in DPN rats. Both 50% PWT and PWL values were markedly decreased in DPN rats. When miR-221 was inhibited, the 50% PWT and PWL values were both significantly increased. Knockdown of miR-221 significantly increased the expression of SOCS3 and decreased the expression of NF-κB. Furthermore, knockdown of miR-221 remarkably decreased the expression of PEG2, BK, IL-6, IL-1β, and TNF-α in both STZ-treated DPN rats and high glucose-induced SH-SY5Y cells, which was reversed by inhibition of SOCS3. The dual luciferase reporter assay showed that miR-221 directly targeted and negatively regulated SOCS3.

CONCLUSIONS

Inhibition of miR-221 can reduce pain and decrease expression of inflammatory factors through targeting SOCS3 in DPN.