The effects of vitamin B۱۲ and diclofenac and their combination on cold and mechanical allodynia in a neuropathic pain model in rats

The present study was performed to investigate the effects of long-term intraperitoneal (IP) injection of vitamin B۱۲ and diclofenac in separate and combined treatments on cold and mechanical allodynia in a neuropathic pain model in rats. Neuropathic pain was induced by crush injury in right tibial nerve. Acetone spray and von Frey tests were used to obtain cold and mechanical allodynia responses, respectively, on day ۱۱ after nerve crush. Normal saline, vitamin B۱۲ and diclofenac were injected intraperitoneally for ۱۰ consecutive days after surgery. Normal saline treated rats showed cold and mechanical allodynia responses after nerve crush. Vitamin B۱۲ at doses of ۵۰, ۱۰۰ and ۲۰۰ µg kg-۱ and diclofenac at a dose of ۲ mg kg-۱ produced antiallodynic effects. Antiallodynic effects were not observed when subanalgesic doses of vitamin B۱۲ (۲۵ µg kg-۱) and diclofenac (۰.۲۵ mg kg-۱) were used together. By increasing the dose of vitamin B۱۲ to an effective dose (۱۰۰ µg kg-۱), antiallodynic effects were observed when compared with diclofenac (۰.۲۵ mg kg-۱) alone. The results indicated that vitamin B۱۲ and diclofenac produced neuropathic pain suppressing effects. Moreover, a potentiation effect was observed between vitamin B۱۲ and diclofenac.

Keywords:

Allodynia , Diclofenac , Rats , Tibial nerve injury , Vitamin B۱۲