The implication of transient receptor potential canonical 6 in BDNF-induced mechanical allodynia in rat model of diabetic neuropathic pain.

Aims: Brain-derived neurotrophic factor (BDNF) is vital in the pathogenesis of mechanical allodynia with a paucity of reports available regarding diabetic neuropathy pain (DNP). Herein we identified the involvement of BDNF in driving mechanical allodynia in DNP rats via the activation of transient receptor potential canonical 6 (TRPC6) channel.

Materials And Methods: The DNP rat model was established via streptozotocin (STZ) injection, and allodynia was assessed by paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). The expression profiles of BDNF and TRPC6 in dorsal root ganglia (DRG) and spinal cord were illustrated by immunofluorescence and Western blotting. Intrathecal administration of K252a or TrkB-Fc was performed to inhibit BNDF/TrkB expression, and respective injection of GsMTX-4, BTP2 and TRPC6 antisense oligodeoxynucleotides (TRPC6-AS) was likewise conducted to inhibit TRPC6 expression in DNP rats. Calcium influx in DRG was monitored by calcium imaging.

Key Findings: The time-dependent increase of BDNF and TRPC6 expression in DRG and spinal cord was observed since the 7th post-STZ day, correlated with the development of mechanical allodynia in DNP rats. Intrathecal administration of K252a, TrkB-Fc, GsMTX-4 and BTP2 prevented mechanical allodynia in DNP rats. Pre-treatment of TRPC6-AS reversed the BDNF-induced pain-like responses in DNP rats rather than the naïve rats. In addition, the TRPC6-AS reversed BDNF-induced increase of calcium influx in DRG neurons in DNP rats.

Significance: The intrathecal inhibition of TRPC6 alleviated the BDNF-induced mechanical allodynia in DNP rat model. This finding may validate the application of TRPC6 antagonists as interesting strategy for DNP management.