No abstract

Neuropathic pain responds poorly to drug treatments, and partial relief is achieved in only about half of the patients. Puerarin, the main constituent of Puerariae Lobatae Radix, has been used extensively in China to treat hypertension and tumor. The current study examined the effects of puerarin on neuropathic pain using two most commonly used animal models: chronic constriction injury (CCI) and diabetic neuropathy. We found that consecutive intrathecal administration of puerarin (4–100 nM) for 7 days inhibited the mechanical and thermal nociceptive response induced by CCI and diabetes without interfering with the normal pain response. Meanwhile, in both models puerarin inhibited the activation of microglia and astroglia in the spinal dorsal horn. Puerarin also reduced the upregulated levels of nuclear factor-κB (NF-κB) and other proinflammatory cytokines, such as IL-6, IL-1β, and TNF-α, in the spinal cord. In summary, puerarin alleviated CCI- and diabetes-induced neuropathic pain, and its effectiveness might be due to the inhibition of neuroinflammation in the spinal cord. The anti-inflammation effect of puerarin might be related to the suppression of spinal NF-κB activation and/or cytokines upregulation. We conclude that puerarin has a significant effect on alleviating neuropathic pain and thus may serve as a therapeutic approach for neuropathic pain.

Inflammatory pain and neuropathic pain are major health issues that represent considerable social and economic burden worldwide. In this study we investigated the potential of obtusifolin and gluco-obtusifolin, two anthraquinones found in the seeds of the widely used traditional Chinese medical botanical Cassia obtusifolia, to reduce neuropathic and inflammatory pain. The potential analgesic effects of obtusifolin and gluco-obtusifolin were evaluated by mice formalin test and complete Freund's adjuvant (CFA)-induced nociceptive behaviors in rats. Chronic constriction injury (CCI), L5 spinal nerve ligation (L5 SNL), diabetes, and chemotherapeutics inducing allodynia were used to test whether repeated treatment with obtusifolin and gluco-obtusifolin ameliorated neuropathic pain. Finally, we explored whether obtusifolin and gluco-obtusifolin altered the degree of neuroinflammation in rat spinal cord after CFA administration and CCI induction. Obtusifolin and gluco-obtusifolin (0.25, 0.5, 1, and 2 mg/kg) reduced licking/biting time in dose-dependent manner in phase 2 of formalin-induced behavior in mice. Furthermore, repeated administration of obtusifolin and gluco-obtusifolin (0.25, 0.5, 1, and 2 mg/kg) reversed mechanical allodynia induced by CFA, CCI, L5 SNL, diabetes, and oxaliplatin in a dose-dependent manner in rats. Levels of activated nuclear factor-kappa B (NF-κB) and proinflammatory cytokines (interleukin (IL)-1β, IL-6, tumor necrosis factor α (TNF-α)) in lumbar spinal cord were elevated in rats following CFA treatment and CCI induction, and obtusifolin and gluco-obtusifolin significantly inhibited these effects. Our results demonstrate that obtusifolin and gluco-obtusifolin produce significant antinociceptive action in rodent behavioral models of inflammatory/neuropathic pain, and that this activity is associated with modulation of neuroinflammation in spinal cord.

Inflammatory pain and neuropathic pain are major health issues that represent considerable social and economic burden worldwide. In this study we investigated the potential of obtusifolin and gluco-obtusifolin, two anthraquinones found in the seeds of the widely used traditional Chinese medical botanical Cassia obtusifolia, to reduce neuropathic and inflammatory pain. The potential analgesic effects of obtusifolin and gluco-obtusifolin were evaluated by mice formalin test and complete Freund's adjuvant (CFA)-induced nociceptive behaviors in rats. Chronic constriction injury (CCI), L5 spinal nerve ligation (L5 SNL), diabetes, and chemotherapeutics inducing allodynia were used to test whether repeated treatment with obtusifolin and gluco-obtusifolin ameliorated neuropathic pain. Finally, we explored whether obtusifolin and gluco-obtusifolin altered the degree of neuroinflammation in rat spinal cord after CFA administration and CCI induction. Obtusifolin and gluco-obtusifolin (0.25, 0.5, 1, and 2 mg/kg) reduced licking/biting time in dose-dependent manner in phase 2 of formalin-induced behavior in mice. Furthermore, repeated administration of obtusifolin and gluco-obtusifolin (0.25, 0.5, 1, and 2 mg/kg) reversed mechanical allodynia induced by CFA, CCI, L5 SNL, diabetes, and oxaliplatin in a dose-dependent manner in rats. Levels of activated nuclear factor-kappa B (NF-κB) and proinflammatory cytokines (interleukin (IL)-1β, IL-6, tumor necrosis factor α (TNF-α)) in lumbar spinal cord were elevated in rats following CFA treatment and CCI induction, and obtusifolin and gluco-obtusifolin significantly inhibited these effects. Our results demonstrate that obtusifolin and gluco-obtusifolin produce significant antinociceptive action in rodent behavioral models of inflammatory/neuropathic pain, and that this activity is associated with modulation of neuroinflammation in spinal cord.

IntroductionThe prevalence of diminished ovarian reserve (DOR), a common gynaecological disorder, is approximately 10% across the world. Failure in early diagnosis and treatment may result in continuous decreases in ovarian function and the resultant loss in an opportunity of pregnancy, which greatly affects the happiness of the women’s family and women’s physical and mental health. Nevertheless, there has been no effective treatment for such a disorder until now. Folic acid, a member of the vitamin B family, is involved in one-carbon cycle and methylation regulation. It has been found that folic acid affects the whole period of pregnancy, and folic acid supplementation has shown effective to remarkably reduce the incidence of fetal neural tube defects and decrease plasma homocysteic acid levels, thereby resulting in a decline in the incidence of abortion. In addition, folic acid is reported to mediate ovarian functions. It is therefore hypothesised that folic acid may improve DOR.Methods and analysisA single-centre, open-label, randomised, placebo-controlled clinical trial is designed. We plan to recruit 140 women with DOR at ages of 30–35 years. All participants will be randomised into the folic acid group and placebo group, and each subject will be given a tablet with the same appearance daily for 6 months. The primary outcome is antral follicle count, and the secondary outcomes are ovarian reserve markers, ovarian low-dose stimulation responses and safety.Ethics and disseminationThis study was approved by the Ethics Review Committee of Nanping First Hospital Affiliated to Fujian Medical University on 10 February 2021 (approval number: NPSY202002042). Written informed consent was obtained from all participants prior to randomisation, following a detailed description of the purpose of the study. The results of this clinical trial will be presented at scientific conferences and submitted to a peer-reviewed journal.Trial registration numberChinese Clinical Trial Registry, ChiCTR2100047410.