Document Type : Original Article

Authors

• Esmaeal Tamaddonfard1 ¹
• Farzad Samadi ²
• Karim Egdami ²

¹ Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran

² Graduated, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran

Abstract

The present study was performed to investigate the effects of long-term intraperitoneal (IP) injection of vitamin B₁₂ 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 11 after nerve crush. Normal saline, vitamin B₁₂ and diclofenac were injected intraperitoneally for 10 consecutive days after surgery. Normal saline treated rats showed cold and mechanical allodynia responses after nerve crush. Vitamin B₁₂ at doses of 50, 100 and 200 µg kg^-1 and diclofenac at a dose of 2 mg kg^-1 produced antiallodynic effects. Antiallodynic effects were not observed when subanalgesic doses of vitamin B₁₂ (25 µg kg^-1) and diclofenac (0.25 mg kg^-1) were used together. By increasing the dose of vitamin B₁₂ to an effective dose (100 µg kg^-1), antiallodynic effects were observed when compared with diclofenac (0.25 mg kg^-1) alone. The results indicated that vitamin B₁₂ and diclofenac produced neuropathic pain suppressing effects. Moreover, a potentiation effect was observed between vitamin B₁₂ and diclofenac.

Keywords

• Allodynia
• Diclofenac
• Rats
• Tibial nerve injury
• Vitamin B12