Physiology
Esmaeal Tamaddonfard; Sina Tamaddonfard; Siamak Cheraghiyan
Volume 9, Issue 4 , December 2018, , Pages 329-335
Abstract
Vitamin B12 modulates pain at the local and peripheral levels. This study has investigated the effects of intracerebroventricular (ICV) injection of vitamin B12 on themuscle pain. We used diclofenac (cyclooxygenase inhibitor) and naloxone (opioid receptors antagonist) to clarify the possible mechanisms. ...
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Vitamin B12 modulates pain at the local and peripheral levels. This study has investigated the effects of intracerebroventricular (ICV) injection of vitamin B12 on themuscle pain. We used diclofenac (cyclooxygenase inhibitor) and naloxone (opioid receptors antagonist) to clarify the possible mechanisms. For ICV injections, a guide cannula was implanted in the left lateral ventricle of the brain. Muscle pain was induced by intramuscular injection of formalin (2.50%; 50 µl) in the right gastrocnemius muscle and the number of paw flinching was recorded at 5-min blocks for 60 min. Locomotor activity was performed using an open-field test. Formalin induced a biphasic pain. Vitamin B12 (1.25, 2.50, 5.00 and 10.00 µg per rat) and diclofenac (12.50 and 25.00 µg per rat) significantly reduced both phases pain intensity. Significant antinociceptive effects were observed after combined treatments of diclofenac (6.25 and 12.50 µg per rat) with vitamin B12 (0.63 and 2.50 µg per rat), respectively. Prior ICV injection of naloxone (10.00 µg per rat) prevented vitamin B12 (10.00 µg per rat) and diclofenac (25.00 µg per rat) induced antinociceptive effects. All the above-mentioned chemicals did not alter locomotor behavior in an open-field test. The present results showed that the cyclooxygenase pathway and opioid receptors may be involved in the central antinociceptive effect of vitamin B12. In addition, opioid receptors might be involved in diclofenac-induced antinociception.
Esmaeal Tamaddonfard1; Farzad Samadi; Karim Egdami
Volume 4, Issue 1 , March 2013, , Pages 19-24
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. ...
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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.