Cellular and Molecular Machinery of Neuropathic Pain: an Emerging Insight

Betaine Attenuates Chronic Constriction Injury-Induced Neuropathic Pain in Rats by Inhibiting KIF17-Mediated Nociception

Kinesin superfamily proteins transport a diverse range of cargo, including excitatory receptors to the dendrite and axon of a neuron via retrograde and anterograde fashions along microtubules, causing central sensitization and neuropathic pain. In this study, we have performed in silico molecular dynamics simulation to delineate the dynamic interaction of betaine with KIF17, a kinesin protein, known to be involved in neuropathic pain. The results from the molecular dynamics study suggest that the betaine-KIF17 complex is stabilized through hydrogen bonding, polar interactions, and water bridges. Findings from in vivo studies suggest a significant increase in pain hypersensitivity, oxido-nitrosative stress, and KIF17 overexpression in the sciatic nerve, dorsal root ganglion (DRG), and spinal cord of nerve-injured rats, which was significantly attenuated on treatment with betaine. Betaine treatment also restored the increased NR2B expressions and levels of proinflammatory cytokines and neuropeptides in the DRG and spinal cord of nerve-injured rats. Findings from the current study suggest that betaine attenuates neuropathic pain in rats by inhibiting KIF17-NR2B-mediated neuroinflammatory signaling.

Caffeic Acid Phenethyl Ester (CAPE) Attenuates Paclitaxel-induced Peripheral Neuropathy: A Mechanistic Study

BACKGROUND

Chemotherapy-induced peripheral neuropathy is a debilitating pain syndrome produced as a side effect of antineoplastic drugs like paclitaxel. Despite efforts, the currently available therapeutics suffer from serious drawbacks like unwanted side effects and poor efficacy and provide only symptomatic relief. Hence, there is a need to find new therapeutic alternatives for the treatment of chemotherapy-induced peripheral neuropathy.

OBJECTIVE

The objective of this study was to explore the protective potential of caffeic acid phenethyl ester in paclitaxel-induced neuropathic pain.

METHODS

We examined the effects of caffeic acid phenethyl ester by administering paclitaxel (2 mg/kg, intraperitoneal) to female Sprague Dawley rats on four alternate days to induce neuropathic pain, followed by the administration of caffeic acid phenethyl ester (10 and 30 mg/kg, intraperitoneally).

RESULTS

Rats that were administered paclitaxel showed a substantially diminished pain threshold and nerve functions after 28 days. A significantly increased protein expression of Wnt signalling protein (β-catenin), inflammatory marker (matrix metalloproteinase 2) and a decrease in endogenous antioxidant (nuclear factor erythroid 2-related factor 2) levels were found in paclitaxel administered rats in comparison to the naïve control group. Caffeic acid phenethyl ester (10 and 30 mg/kg, intraperitoneal) showed improvements in behavioural and nerve function parameters along with reduced expression of β-catenin, matrix metalloproteinase 2 and an increase in nuclear factor erythroid 2- related factor 2 protein expression.

CONCLUSION

The present study suggests that caffeic acid phenethyl ester attenuates chemotherapyinduced peripheral neuropathy via inhibition of β-catenin and matrix metalloproteinase 2 and increases nuclear factor erythroid 2-related factor 2 activation.