Biological & pharmaceutical bulletin
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Application of camphor to the skin has been empirically thought to improve blood circulation. However, camphor's effects on blood circulation to the skin and on thermal sensation have not been well elucidated. In this study, we examined its effects on the quality of sensation as well as on skin and muscle blood flow in human. ⋯ Finally, we measured blood flow in skin and muscle after the application of camphor or menthol. Application of camphor or menthol separately induced increases in local blood flow in the skin and muscle. The present results indicate that camphor induces both cold and warm sensations and improves blood circulation.
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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. ⋯ 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.
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Observational Study
A retrospective study on the influence of nutritional status on pain management in cancer patients using the transdermal fentanyl patch.
It is unknown whether nutritional status influences pain intensity in cancer patients receiving a transdermal fentanyl patch (FP). This study aimed to determine whether nutritional status is associated with pain intensity and to evaluate the influence of changes in nutritional status on pain intensity in cancer patients receiving transdermal FP treatment. We included 92 patients receiving transdermal FP treatment for the first time with switching from oxycodone. ⋯ In 52 of 92 patients, who were evaluated using the NRS 2002 score and pain intensity on day 30 after FP application, the changes in NRS 2002 scores were significantly related to changes in pain intensities (odds ratio, 30.0; 95% confidence interval, 4.48-200.97; p=0.0005). These results suggest that an increase in the NRS 2002 score is a risk factor for an increase in pain intensity in cancer patients receiving FP treatment. Malnutrition may lead to poor pain management in cancer patients receiving FP treatment.
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Diabetic neuropathy is characterized by progressive degeneration of nerve fibers associated with diabetes mellitus. Antidepressants and anticonvulsants are the mainstay of pharmacological treatment, but are often limited in effectiveness against the core clinical feature of pain. In the current study, we examined the potential effects of koumine, a Gelsemium elegans Benth alkaloid, using a rat model of diabetic neuropathy. ⋯ At a dose of 7 mg/kg, koumine was more effective than gabapentin (100 mg/kg), and decreased mechanical sensitivity threshold to a level comparable to healthy control. Repeated treatment of koumine significantly reduced the damage to axon and myelin sheath of the sciatic nerve and increased SNCV, without affecting body weight and blood glucose. These findings encourage the use of koumine in the treatment of diabetic neuropathy.
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Pregabalin, (S)-3-isobutyl-γ-aminobutyric acid (GABA), is a widely used adjuvant therapy for patients with neuropathic pain, which is defined as chronic pain caused by lesions or diseases of the somatosensory nervous system. However, dizziness and somnolence (sleepiness) are common dose-limiting side effects, probably due to excessive sedative effects on higher centers of the central nervous system (CNS) which are involved in the anticonvulsant and analgesic actions of pregabalin. We speculated that transdermal delivery would minimize centrally mediated side effects. ⋯ Transdermally administered pregabalin increased the pain thresholds in response to mechanical stimuli in a partial sciatic nerve ligation model in rats and a spinal nerve ligation model in mice, and surprisingly also in normal animals. It is noteworthy that simple transdermal application of an aqueous solution of pregabalin is effective. This could be a useful treatment option to avoid or minimize the CNS-mediated side effects of orally administered pregabalin.