Introduction: Neuropathic pain is a common and painful somatosensory nervous system disease, and its treatment remains a medical challenge. Evidence demonstrates that gut microbiota alters in neuropathic pain and, therefore, improvement of the gut flora may affect the disease. The present study aimed to evaluate the antinociceptive effect of probiotics in neuropathic pain and oxidative biomarkers' responsiveness to the probiotic treatment.
Methods: Using chronic constriction injury (CCI) of the rats' sciatic nerve, neuropathic pain was induced. Investigating the analgesic effect of the probiotics mixture, 40 male rats were randomly assigned to 4 groups (n=10 for each): Sham-operated (SM), and CCI model rats orally received 1 mL saline (CS), or 100 mg/kg gabapentin (CG) or 1 mL probiotics mixture (CP) Lactobacillus plantarum, Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Bifidobacterium bifidum (109 CFU of each) daily. Using behavioral tests, the pain was assessed on days 1, 4, 7, 14, and 21 of the study. Finally, the biochemical evaluation of sciatic nerve tissue was done.
Results: Probiotics decreased cold and mechanic allodynia and thermal hyperalgesia. Reducing lipid peroxidation levels and increasing total antioxidant capacity, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity were also significant in the probiotics group.
Conclusion: These findings suggest that probiotics have analgesic effects on the CCI model of neuropathic pain via increasing the antioxidant capacity of the rats' sciatic nerve.
Highlights: Oral probiotics mixture diminishes cold and mechanical allodynia in chronic constriction injury (CCI) rats.Probiotics mixture reduces thermal hyperalgesia in CCI rats as well as gabapentine.Balancing in oxidant/anti-oxidant system is key pathway in neuropathic pain reduction.
Plain language summary: Currently, neuropathic pain is an underestimated socioeconomic health problem affecting millions of people worldwide. Neuropathic pain occurs when a health condition affects the nerves that carry sensations to the brain. With neuropathic pain, the pain isn't typically triggered by an event or injury. Instead, the body sends pain signals to the brain unprompted. Neuropathic pain tends to get worse over time. As neuropathic pain could result from an imbalance in the oxidative/antioxidative system, antioxidant supplementation may be a treatment option. Oxidative stress is known to result in the occurrence of molecular mechanisms of diabetes, atherosclerosis, inflammatory bowel disease, and damage to the heart, brain, or transplanted organs. Probiotics are made of good live bacteria and/or yeasts that naturally live in the body and have various health benefits. Consumption of probiotics alone or foods supplemented with probiotics may reduce cell oxidative damage. Incorporating probiotics in foods can provide an excellent strategy to supply dietary antioxidants. This study subjected rats to sciatic nerve ligation to induce neuropathic pain. The oral probiotics mixture was administered for 21 days post-surgery. The result showed that the probiotics mixture administration could reduce oxidative stress and pain in neuropathic pain rats. Therefore, probiotics can prevent and treat many systemic diseases in animal and human studies.
Keywords: Allodynia; Antioxidants; Chronic constriction injury; Hyperalgesias; Neuropathic pain; Probiotics; Rats.
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