• The Korean Journal of Pain
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• v.33 no.4
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• pp.359-377
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• 2020

Background: This study investigated whether current smoking and a higher nicotine dependency were associated with chronic low back pain (LBP), lumbar related leg pain (sciatica) and/or radicular neuropathic pain. Methods: A cross-sectional study was conducted on 150 patients (mean age, 60.1 ± 13.1 yr). Demographic data, the International Association for the Study of Pain (IASP) neuropathic pain grade, STarT Back tool, and the Fagerström test were completed. A control group (n = 50) was recruited. Results: There was a significant difference between current smokers and nonsmokers in the chronic LBP group in the mean pain score (P = 0.025), total STarT Back score (P = 0.015), worst pain location (P = 0.020), most distal pain radiation (P = 0.042), and in the IASP neuropathic pain grade (P = 0.026). There was a significant difference in the mean Fagerström score between the four IASP neuropathic pain grades (P = 0.005). Current smoking yielded an odds ratio (OR) of 3.071 (P = 0.011) for developing chronic LBP and sciatica, and an OR of 4.028 (P = 0.002) for obtaining an IASP "definite/probable" neuropathic pain grade, for both cohorts. The likelihood for chronic LBP and sciatica increased by 40.9% (P = 0.007), while the likelihood for an IASP neuropathic grade of "definite/probable" increased by 50.8% (P = 0.002), for both cohorts, for every one unit increase in the Fagerström score. Conclusions: A current smoking status and higher nicotine dependence increase the odds for chronic LBP, sciatica and radicular neuropathic pain.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.1
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• pp.79-89
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• 2013

PURPOSE: To identify the effects of single trial transcutaneous electrical nerve stimulation (TENS) application on chronic neuropathic pain and the repeated TENS application to development of neuropathic pain following peripheral nerve injury. METHODS: First, 20 rats were given the median nerve ligation to induce chronic neuropathic pain. After the ligation, neuropathic pain was assessed by measuring the forepaws withdrawal threshold to von Frey filaments for 3 weeks. Afterward, rats were randomly divided into TENS group and placebo-TENS group. TENS (frequency 100Hz, pulse width $200{\mu}s$) was applied to the forearm for 20 minutes. Second, 34 rats were randomly allocated into two group after median nerve ligation: TENS group and placebo-TENS group. Both interventions were applied to the forearm for 20 minutes from 1 day to 3 weeks after injury. Neuropathic pain to mechanical was measured on each rat for 3 weeks. RESULTS: Exeprimental rats showed a clear neuropathic pain-like behaviors, such as reduced forepaw withdrawal threshold to mechanical stimulation for 3 weeks, after median nerve ligation. And, TENS decreased effectively the chronic neuropathic pain originated from median nerve injury. TENS also diminished the development of neuropathic pain after nerve injury. CONCLUSION: Our animal model studying for neuropathic pain following median nerve injury may be useful to investigate peripheral neuropathic pain in human. Also, TENS may be used to mediate chronic neuropathic pain and to prevent the development of neuropathic pain following median nerve injury.

• Korean Journal of Medicinal Crop Science
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• v.16 no.3
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• pp.183-187
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• 2008

Nerve injury can lead to neuropathic pain, which is often resistant to current analgesics and interventional therapeutic methods. Extracellular signal-regulated kinase (ERK) plays important role in the induction of neuropathic pain. We explored the antinociceptive effect of curcumin and its effect on ERK in the spinal cord in the neuropathic pain model of rats induced by chronic constriction injury (CCI) of the sciatic nerve. In injured rats, mechanical allodynia, which is one of characteristics of neuropathic pain developed and the activation of ERK in spinal cord significantly increased compared with control group. However, administration of curcumin (50 mg/kg/day p.o) for 7 days started from one day before the injury prevented the development of mechanical allodynia and increase of ERK phosphorylation. These results indicate that curcumin can be a new therapeutic agent in the treatment of neuropathic pain.

• The Korean Journal of Pain
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• v.27 no.3
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• pp.246-252
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• 2014

Background: Neuropathic pain is generally defined as a chronic pain state resulting from peripheral and/or central nerve injury. There is a lack of effective treatment for neuropathic pain, which may possibly be related to poor understanding of pathological mechanisms at the molecular level. Curcumin, a therapeutic herbal extract, has shown to be effectively capable of reducing chronic pain induced by peripheral administration of inflammatory agents such as formalin. In this study, we aimed to show the effect of curcumin on pain behavior and serum COX-2 level in a Chronic Constriction Injury (CCI) model of neuropathic pain. Methods: Wistar male rats (150-200 g, n = 8) were divided into three groups: CCI vehicle-treated, sham-operated, and CCI drug-treated group. Curcumin (12.5, 25, 50 mg/kg, IP) was injected 24 h before surgery and continued daily for 7 days post-surgery. Behavioral tests were performed once before and following the days 1, 3, 5, 7 after surgery. The serum COX-2 level was measured on day 7 after the surgery. Results: Curcumin (50 mg/kg) decreased mechanical and cold allodynia (P < 0.001) and produced a decline in serum COX-2 level (P < 0.001). Conclusions: A considerable decline in pain behavior and serum COX-2 levels was seen in rat following administration of curcumin in CCI model of neuropathic pain. High concentration of Curcumin was able to reduce the chronic neuropathic pain induced by CCI model and the serum level of COX-2.

• The Korean Journal of Pain
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• v.21 no.2
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• pp.112-118
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• 2008

Background: This study was conducted to quantitatively analyze proteins associated with the calcitonin gene-related peptide (CGRP) in cerebrospinal fluid (CSF) that was obtained from a rat model of chronic neuropathic pain following administration of intrathecal $CGRP_{8-37}$. Methods: Male Sprague-Dawley rats (100-150 g, 5-6 wks) were divided into two groups, sham controls and neuropathic pain models. At the time of operation for neuropathic pain model, an intrathecal catheter was threaded through the intrathecal space. At 1 or 2 wks after the operation (maximum pain state), a test dose of 1, 5, 10, or 50 nM of $CGRP_{8-37}$ was injected into the intrathecal catheter and the CSF was then aspirated. Conventional proteomics to evaluate the CSF were then performed using high resolution 2-D, gel electrophoresis followed by computational image analysis and protein identification by mass spectrometry. Results: Treatment with $CGRP_{8-37}$ effectively alleviated mechanical allodynia in a dose dependent manner. The most effective response was obtained when a dose of 50 nM was administered, but significant differences were obtained following administration of only 5 nM $CGRP_{8-37}$. Furthermore, the results of the proteomic analysis were consistent with the experimental results. Specially we detected 30 differentially expressed spots in 7 images when 2-D gel electrophoresis was conducted. The intensity of 6 of these spots (spot number: 20 and 26-30) was found decrease the $CGRP_{8-37}$ dose increased; therefore, these spots were evaluated by mass spectrometry. This analysis identified 2 different proteins, CGRP (spot numbers: 26-30) and neurotensin-related peptide (spot number: 20). Conclusions: The results of this study suggest that CGRP plays a role in chronic central neuropathic pain and is a major target of chronic neuropathic pain management.

• The Korean Journal of Pain
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• v.37 no.2
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• pp.107-118
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• 2024

Nociplastic pain by the "International Association for the Study of Pain" is defined as pain that arises from altered nociception despite no clear evidence of nociceptive or neuropathic pain. Augmented central nervous system pain and sensory processing with altered pain modulation are suggested to be the mechanism of nociplastic pain. Clinical criteria for possible nociplastic pain affecting somatic structures include chronic regional pain and evoked pain hypersensitivity including allodynia with after-sensation. In addition to possible nociplastic pain, clinical criteria for probable nociplastic pain are pain hypersensitivity in the region of pain to non-noxious stimuli and presence of comorbidity such as generalized symptoms with sleep disturbance, fatigue, or cognitive problems with hypersensitivity of special senses. Criteria for definitive nociplastic pain is not determined yet. Eight specific disorders related to central sensitization are suggested to be restless leg syndrome, chronic fatigue syndrome, fibromyalgia, temporomandibular disorder, migraine or tension headache, irritable bowel syndrome, multiple chemical sensitivities, and whiplash injury; non-specific emotional disorders related to central sensitization include anxiety or panic attack and depression. These central sensitization pain syndromes are overlapped to previous functional pain syndromes which are unlike organic pain syndromes and have emotional components. Therefore, nociplastic pain can be understood as chronic altered nociception related to central sensitization including both sensory components with nociceptive and/or neuropathic pain and emotional components. Nociplastic pain may be developed to explain unexplained chronic pain beyond tissue damage or pathology regardless of its origin from nociceptive, neuropathic, emotional, or mixed pain components.

• The Korean Journal of Pain
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• v.37 no.4
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• pp.299-309
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• 2024

Chronic peripheral neuropathic pain therapy currently focuses on modulating neuroinflammatory conditions. Methylcobalamin (MeCbl), a neuroregenerative agent, modulates neuroinflammation. This review aimed to explore the molecular pharmacology action of MeCbl as a chronic peripheral neuropathic pain therapeutic agent. MeCbl plays a role in various cellular processes and may have therapeutic potential in neurodegenerative diseases. Intracellular MeCbl modulates inflammation by regulating the activity of T lymphocytes and natural killer cells as well as secretion of inflammatory cytokines, namely, tumor necrosis factor-α, interleukin-6, interleukin-1β, epidermal growth factor, and neuronal growth factor. MeCbl can reduce pain symptoms in chronic neuropathic pain conditions by decreasing excitation and hyperpolarization-induced ion channel activity in medium-sized dorsal root ganglion (DRG) neurons and the expression of transient receptor potential ankyrin 1, transient receptor potential cation channel subfamily M member 8, phosphorylated p38MAPK, transient receptor potential cation channel subfamily V members 1 and 4 in the DRG, and the voltage-gated sodium channel in axons.

• The Korean Journal of Pain
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• v.28 no.4
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• pp.231-235
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• 2015

Damage to peripheral nerves or the spinal cord is often accompanied by neuropathic pain, which is a complex, chronic pain state. Increasing evidence indicates that alterations in the expression and activity of gap junction channels in the spinal cord are involved in the development of neuropathic pain. Thus, this review briefly summarizes evidence that regulation of the expression, coupling, and activity of spinal gap junction channels modulates pain signals in neuropathic pain states induced by peripheral nerve or spinal cord injury. We particularly focus on connexin 43 and pannexin 1 because their regulation vastly attenuates symptoms of neuropathic pain. We hope that the study of gap junction channels eventually leads to the development of a suitable treatment tool for patients with neuropathic pain.

• Annals of Clinical Neurophysiology
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• v.25 no.2
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• pp.78-83
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• 2023

Nociplastic pain refers to pain arising from altered nociception without evidence of tissue or somatosensory damage. It encompasses various clinical conditions with shared neurophysiological mechanisms involving different organ systems. Nociplastic pain can occur independently or alongside chronic pain conditions with a nociceptive or neuropathic origin. This review introduces the concept of nociplastic pain, its clinical manifestations and the underlying pathophysiology. Taking a biopsychosocial approach can lead to a better understanding of nociplastic pain and improved treatment outcomes for affected individuals.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.2
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• pp.69-75
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• 2022

Chronic pain is induced by tissue or nerve damage and is accompanied by pain hypersensitivity (i.e., allodynia and hyperalgesia). Previous studies using in vivo two-photon microscopy have shown functional and structural changes in the primary somatosensory (S1) cortex at the cellular and synaptic levels in inflammatory and neuropathic chronic pain. Furthermore, alterations in local cortical circuits were revealed during the development of chronic pain. In this review, we summarize recent findings regarding functional and structural plastic changes of the S1 cortex and alteration of the S1 inhibitory network in chronic pain. Finally, we discuss potential neuromodulators driving modified cortical circuits and suggest further studies to understand the cortical mechanisms that induce pain hypersensitivity.