Background
This study aimed to evaluate the effect of nanoemulsion containing peppermint and rosemary essential oils in rats with osteoarthritis (OA).
Methods
In this experimental study, we prepared a nanoemulsion containing peppermint and rosemary essential oils by spontaneous emulsification and evaluated the nanoemulsion’s dermal irritation and toxicity. Investigating the analgesic effect of the nanoemulsion, we randomly assigned 36 male rats to 6 groups: Control (saline injection into the knee), osteoarthritis (intra-articular injection of 2 mg monosodium iodoacetate), and four groups of OA treated with nanoemulsion gel, nanoemulsion solution, rosemary and peppermint essential oil gel, or diclofenac sodium. Treatments were administered topically at a dose of 1 ml daily. Using behavioral tests, we assessed pain on days 1, 4, 7, and 14 after injection. Finally, we did the histopathological and biochemical evaluation of rats’ knee joints.
Results
There were no irritation signs on the animals’ skin after receiving the nanoemulsion and no changes in the hematological and biochemical parameters of rats’ blood compared to the control group. Receiving nanoemulsion decreased the mechanical (P < 0.001) and thermal allodynia (P < 0.05), thermal hyperalgesia (P < 0.05), and ambulatory-evoked pain in comparison with the OA group. Also, the nanoemulsion receiving rats showed an increase in SOD and GPx activity and a decrease in MDA level. Histopathology of synovial tissues confirmed the results of behavioral and biochemical tests.
Conclusion
The nanoemulsion containing essential oils of peppermint and rosemary reduces osteoarthritis pain via increasing antioxidant capacity and improving the histopathological features of the rats’ knee joint.
Background: 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 have 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 level and increasing total antioxidant capacity, SOD, and GPx activity was also significant in the probiotics group. Conclusions: These findings suggest that probiotics have analgesic effects on the chronic constriction injury (CCI) model of neuropathic pain via increasing antioxidant capacity of the rats' sciatic nerve.
Aims: As effective herbal materials, flavonoids and the phenolic compounds are with anti-pain and anti-inflammatory effects. Based on the studies, there is a huge amount of polyphenols and flavonoids in the leaves of Morus alba L. Therefore, the aim of this study was to investigate the anti-pain effects of alcoholic extract of the leaves of Morus alba L. on the rats.
Materials & Methods:In the experimental study, 32 male Wistar rats were divided into 4 groups including control group and groups receiving 100, 200, and 400mg/kg alcoholic extract of the leaves of Morus alba L. There was 4-week daily extract gavage. The anti-pain effect of the extract was investigated through thermal hyperalgesia, writhing, tail flick, and formalin tests. Data was analyzed by SPSS 16 software using one-way ANOVA and Tukey's post-hoc tests. Findings: Daily use of 100, 200, and 400mg/kg of alcoholic extract of the leaves of Morus alba L. for 4 weeks led to significant increases in the mean foot withdrawal latency (p<0.001) and mean tail withdrawal latency (p<0.001) and significant reductions in the percentage of abdominal constriction (p<0.001) and pain feeling in both acute (p<0.05) and chronic (p<0.01) phases of formalin test than control group. Nevertheless, the effect of 200mg/kg dose was higher than the other doses. Conclusion: Oral consumption of the alcoholic extract of the leaves of Morus alba L. leads to a reduction in pain feeling in the rats. In addition, the anti-pain effect of 200mg/kg dose is higher than other doses.
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