Anti-Neuropathic Efficacy of Homoeopathic Dilutions of <i>Toxicodendron pubescens</i>: A Preclinical Study

Background: Toxicodendron pubescens Mill., the botanical name of Rhus toxicodendron (Rhus tox), also known as ‘poison ivy’, belongs to the family of Anacardiaceae and is widely used in the traditional system of Homoeopathy medicine. Its crude form and various dilutions are most commonly used to relieve arthritis symptoms, are beneficial as an anti-inflammatory and are also used for edema-related conditions. Aim: The study aims to evaluate the anti-neuropathic efficacy of the crude and diluted forms of Rhus tox, a homoeopathic preparation, using the chronic constriction injury (CCI) rat model. Methods: In the current study, before conducting the in vivo study, the cell viability study on Rhus tox dilutions was determined using the MTT assay with Lipopolysaccharide-treated U-87 glioblastoma cells. Consequently, the effect of the drug on mechanical, cold, and hot allodynia and motor nerve conduction velocity was determined. The levels of antioxidants, proinflammatory markers, and histopathological changes were also evaluated. Results: The 14-day treatment regimen with Rhus tox in the chronic constriction model mitigated behavioural alterations such as mechanical and thermal allodynia with an improvement in the conduction velocity in the sciatic nerve as compared to the corresponding groups. The dilutions were also capable of normalising the altered oxidative and inflammatory markers. The anti-neuropathic efficacy was further confirmed by the improved nerve architecture and reduced infiltration of inflammatory cells in histopathological examination. Conclusion: The present observations support the efficacy of ultra-dilutions of Rhus tox in the rodent CCI model of neuropathic pain through its antioxidant, anti-inflammatory, and modulatory effects on neuropathic pain. Major Findings: Rhus tox showed a cytoprotective effect on LPS-induced U-87 glioblastoma cells. Treatment with Rhus tox in CCI rats attenuated thermal and mechanical allodynia and normalised the nerve conduction. Rhus tox normalised oxidative stress and inflammatory levels, improved nerve architecture, and reduced inflammatory cell infiltration.