Alpha-lipoic acid downregulates TRPV1 receptor via NF-κB and attenuates neuropathic pain in rats with diabetes

Abstract

Aims: Painful diabetic neuropathy (PDN) is a refractory complication of diabetes. The study aimed to investigate the role of α-lipoic acid (ALA) on the regulation of transient receptor potential vanilloid-1 (TRPV1) in dorsal root ganglion (DRG) neurons of rats with diabetes. Methods: Whole-cell patch-clamp recordings were employed to measure neuronal excitability in DiI-labeled DRG neurons of control and streptozotocin (STZ)-induced diabetic rats. Western blotting and immunofluorescence assays were used to determine the expression and location of NF-κBp65 and TRPV1. Results: STZ-induced hindpaw pain hypersensitivity and neuronal excitability in L4-6 DRG neurons were attenuated by intraperitoneal injection with ALA once a day lasted for one week. TRPV1 expression was enhanced in L4-6 DRGs of diabetic rats compared with age-matched control rats, which was also suppressed by ALA treatment. In addition, TRPV1 and p65 colocated in the same DRG neurons. The expression of p65 was upregulated in L4-6 DRGs of diabetic rats. Inhibition of p65 signaling using recombinant lentiviral vectors designated as LV-NF-κBp65 siRNA remarkably suppressed TRPV1 expression. Finally, p65 expression was downregulated by ALA treatment. Conclusion: Our findings demonstrated that ALA may alleviate neuropathic pain in diabetes by regulating TRPV1 expression via affecting NF-κB.