• The Korean Journal of Pain
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• v.11 no.1
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• pp.23-29
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• 1998

Background: The present study was conducted to investigate effects of microinjection of bicuculline, GABA-A receptor antagonist, into the brain stem nuclei on the dorsal horn neuron responsiveness in rats with an experimental peripheral neuropathy. Methods: An experimental neuropathy was induced by a unilateral ligation of L5~L6 spinal nerves of rats. After 2~3 weeks after the surgery, single-unit recording was made from wide dynamic range (WDR) neurons in the spinal cord dorsal horn. Results: Responses of WDR neurons to both noxious and innocuous mechanical stimuli applied to the somatic receptive fields were enhanced on the nerve injured side. These enhanced responsiveness of WDR neurons were suppressed by microinjection of bicuculline into periaqueductal gray(PAG) or nucleus reticularis gigantocellularis(Gi). A similar suppression was also observed when morphine was microinjected into PAG or Gi. Suppressive action by Gi-bicuculline was reversed by naloxonazine, ${\mu}$-opioid receptor antagonist, microinjected into PAG whereas PAG-bicuculline induced suppression was not affected by naloxonazine injection into Gi. Gi-bicuculline induced suppression were reversed by a transection of dorsolateral funiculus(DLF) of the spinal cord. Conclusions: The results suggest that endogenous opioids, via acting on GABAergic interneurons in PAG and Gi, may be involved in the control of neuropathic pain by activating the descending inhibitory pathways that project to the spinal dorsal horn through DLF to inhibit the responsiveness of WDR neurons.

• Journal of Physiology & Pathology in Korean Medicine
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• v.32 no.1
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• pp.35-42
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• 2018

TRPA1 and TRPV1 are members of the TRP superfamily of structurally related, nonselective cation channels. TRPA1 and TRPV1 are often co-expressed in sensory neurons and play an important role in mechanical hyperalgesia and allodynia during neuropathic pain. Scutellariae Radix was reported to possess anti-inflammation properties and similar patterns of therapeutic action against different diseases. also Baicalin(a known principal constituent of Scutellaria Radix) was shown to down-regulate the mRNA expression levels of TRPV1. In this study, we observed the effects of Scutellariae Radix extract(SRE) in neuropathic pain induced SD rats via modulation of TRPV1 and TRPA1. Oral administration of a Scutellaria Radix extract(in doses of 300mg/kg, SRE(300)) showed a meaningful increase in the withdrawal threshold of mechanical allodynia and showed a meaningful decrease in the expression of c-fos compared to the control group. SRE(100) and SRE(300) showed a meaningful decrease in the expression of TRPV1 level compared to the control group. These results suggest that Scutellariae Radix extract could decrease mechanical allodynia by down-regulate the TRPV1 on the model of neuropathic pain.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.3
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• pp.241-249
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• 1997

The aim of the present study is to examine the brainstem sites where the electrical stimulation produces a suppression of dorsal horn neuron responses of neuropathic rats. An experimental neuropathy was induced by a unilateral ligation of L5-L6 spinal nerves of rats. Ten to 15 days after surgery, the spinal cord was exposed and single-unit recording was made on wide dynamic range (WDR) neurons in the dorsal horn. Neuronal responses to mechanical stimuli applied to somatic receptive fields were examined to see if they were modulated by electrical stimulation of various brainstem sites. Electrical stimulation of periaqueductal gray (PAG), n. raphe magnus (RMg) or n. reticularis gigantocellularis (Gi) significantly suppressed responses of WDR neurons -to both noxious and non-noxious stimuli. Electrical stimulation of other brainstem areas, such as locus coeruleus. (LC) and n. reticularis paragigantocellularis lateralis (LPGi), produced little or no suppression. Microinjection of morphine into PAG, RMg, or Gi also produced a suppression as similar pattern to the case of electrical stimulation, whereas morphine injection into LC or LPGi exerted no effects. The results suggest that PAG, NRM and Gi are the principle brainstem nuclei involved in the descending inhibitory systems responsible for the control of neuropathic pain. These systems are likely activated by endogenous opioids and exert their inhibitory effect by acting on WDR neurons in the spinal cord.

• Korean Journal of Acupuncture
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• v.36 no.4
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• pp.264-273
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• 2019

Objectives : Microglia play a crucial role in electroacupuncture (EA) analgesia on neuropathic pain. The role of chemokines in producing analgesic effects of EA, however, is largely unknown. In the present study, we investigated the role of chemokines in producing analgesic effects of EA in the neuropathic pain model. Methods : Sprague-Dawley rats were randomly assigned into three groups (anesthetized group (ANE), non-acupoint EA group (NAP), and ST36 - GB34 EA group (ACU)). Neuropathic pain was induced by tight ligation of L5 spinal nerve. Mechanical and thermal hypersensitivity of hind paw was tested. Western blot tests and immunofluorescence assay for C-C motif chemokine ligand 2 (CCL2) levels and microglia activation were performed on spinal cord L5/6. EA was treated once daily from the 3rd day after surgery for 5 days. Results : EA treatments applied to ST36 and GB34 significantly reduced both mechanical and thermal hypersensitivity after two and three times of treatment, respectively. While CCL2 expression significantly increased in neuropathic rats, it was significantly reduced in the ACU. In addition, co-localization of CCL2 and activated microglia significantly decreased in the ACU compared to those of ANE and NAP in the spinal cord L5/L6 dorsal horn. Conclusions : The present results suggest that EA applied to ST36 and GB34 modulates the reduction of CCL2 release from the injured neurons and consequently decreases microglia activation in the spinal cord. Regulation of chemokine induced spinal activation of microglia plays a key role in analgesic effects of EA in the rat model of neuropathic pain.

• Journal of Acupuncture Research
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• v.18 no.6
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• pp.215-224
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• 2001

Objcetive : Neuropathic pain sometimes arises from a partial peripheral nerve injury. This kind of pain is usually accompanied by spontaneous burning pain, allodynia and hyperalgesia. It has been well known that acupuncture is effective to the pain control from ancient time in Asia. However, it is not clear whether acupuncture can control neuropathic pain. The aim of the present study is to examine if acupuncture stimulation may be effective to the mechanical allodynia in a rat model of neuropathic pain. Methods : To produce neuropathic pain, under sodium pentobarbital anesthesia, the right superior caudal trunk was resected between the S3 and S4 spinal nerves. After the neuropathic surgery, we examined if the animals exhibited the behavioral signs of mechanical allodynia. The mechanical allodynia was assessed by stimulating the tail with von Frey hair (bending force : 2.0g). three or 6 weeks after the neuropathic surgery, acupuncture stimulation was delivered to Houxi (SI 3) as the following parameters (2HZ frequency, 0.07mA intensity and 3msec duration) for 30 minutes. Results : The stimulation of Houxi (SI 3) acupoint relieved the behavioral signs of mechanical allodynia. Conclusion : Our results suggest that acupuncture can control the mechanical allodynia of neuropathic pain.

• Journal of The Korean Dental Society of Anesthesiology
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• v.3 no.1 s.4
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• pp.6-9
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• 2003

Background: The use of neurolytic agents to control neuropathic pain has been described from the last century Phenol and ethyl alcohol have been widely used as neurolytic agents, however, their neurolytic effect is variable in efficacy and duration of action, and infrequently accompanied with grave complications. It has been found that 5% lidocaine causes irreversible conduction blockade in animal studies. The goal of this study was to evaluate the neurolytic effect of 5%o lidocaine on various neuropathic pain syndromes for prolonged analgesia. Methods: Twenty-five patients with a diagnosis of neuropathic pain including trigeminal neuralgia (n = 7), postherpetic neuralgia (n = 10), and postsurgical neuralgia (n = 8) were selected after failure of routine therapeutic regimens. After performing a diagnostic nerve block with 1% lidocaine and 5% lidocaine was injected. The patients were followed for 6 months. Visual analog scale (VAS) scores and side effects were recorded for each patients. Results: A significant decrease in pain scores after neurolytic blockade with 5% lidocaine was seen in all of three pain groups. All the patients reported immediate and prolonged pain relief lasting from 4 weeks to 6 months. None of patients exhibited any appreciable side effects or complications. Conclusions: We suggest that 5% lidocaine may be used safely and effectively for the purpose of prolonged analgesia in selected patients with intractable neuropathic pain syndromes.

• Herbal Formula Science
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• v.29 no.4
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• pp.229-237
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• 2021

Objectives: This study aimed to analyze the effectiveness of Sogunjung-tang on neuropathic pain. Methods: This study was conducted on 50 cases of patients with neuropathic pain who were treated in LUA clinic from Jun 2021, to Oct 2021. All patients were treated with Sogunjung-tang, and in some cases, acupuncture or moxibustion was also performed. We measured the efficacy of treatment with a numerical rating scale (NRS), frequency, and duration of pain before treatment, after 1 week, and 3 weeks. Results: Both average pain NRS and worst pain NRS significantly decreased 1 week and 3 weeks after treatment compared to pre-treatment. The frequency and duration of pain did not differ after 1 week of treatment but showed a significant difference after 3 weeks. Conclusions: This study suggests that herbal medicine treatment with Sogunjung-tang reduces pain intensity, frequency, and duration in patients with neuropathic pain.

• Korean Journal of Acupuncture
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• v.36 no.1
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• pp.52-62
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• 2019

Objectives : The objective of this study was to investigate the effects of Zingiberis Rhizoma Pharmacopuncture(ZP) at GB30 and ST36 in neuropathic pain induced SD rats by the block of Transient Receptor Potential Vanilloid 1(TRPV1). Methods : Neuropathic pain in rats was induced by tibial and common peroneal nerve transection of right leg. The rat subjects were divided into 6 groups : normal(Nor, n=5), control(Con, n=5), neuropathic pain plus 2 mg/kg ZP injection at GB30 and ST36(ZP-A, n=5), 10 mg/kg ZP(ZP-B, n=5), 20 mg/kg ZP(ZP-C, n=5) and 0.45 mg/kg Tramadol(Tra, n=5). Three days after the surgery, injections were administered once a day for 17 days. Withdrawal response of neuropathic rats' legs were measured by stimulating the paw of Right leg with von frey filament, acetone and radient heat on day 3, 7, 11, 15, 19 after surgery. After all treatments were completed, c-Fos in the midbrain central gray and TRPV1 & TRPA1 of DRG(L5) were analyzed. Results : Groups ZP-B and ZP-C showed a meaningful decrease in the withdrawal response of mechanical allodynia, thermal hyperalgesia and cold allodynia compared to the control group(p<0.05, p<0.01, p<0.001). Groups ZP-B and ZP-C showed a meaningful decrease in the expression of c-fos and TRPV1 protein level compared to the control group(p<0.05, p<0.01, p<0.001). Conclusions : These results suggest that Zingiberis Rhizoma Pharmacopuncture at GB30 and ST36 could decrease mechanical & cold allodynia and thermal hyperalgesia by block the TRPV1 on the model of neuropathic pain.

• Journal of Korean Foot and Ankle Society
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• v.26 no.4
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• pp.177-182
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• 2022

Purpose: The efficacy and safety of low-dose pregabalin and alpha lipoic acid in diabetic neuropathy were evaluated and analyzed. Materials and Methods: This study designed a retrospective study that included patients with diabetic neuropathic pain. From 2009 to 2022, 100 patients who suffered from diabetic neuropathic pain were included in this study. The patients were divided into group I (pregabalin 150 mg/day with alpha lipoic acid 600 mg/day) and group II (pregabalin 300 mg/day with alpha lipoic acid 600 mg/day). The visual analogue scale (VAS), medication side effects, and neurometer results were compared. Results: The mean follow-up period of the above patients was 120.23 weeks in group I and 149.05 weeks in group II. The average VAS score in group I decreased by 3.23 points, and the average VAS score in group II decreased by 2.86 points. Approximately 24.3% of group I had side effects, such as dizziness, sleepiness, and gastrointestinal trouble, while 76.7% of patients in group II had side effects. Sixtyseven patients had a neurometer examination before and after the medication, and there is no statistical difference between the two groups. Conclusion: The combination of low-dose pregabalin (pregabalin 150 mg/day) and alpha lipoic acid in diabetic neuropathy had a similar clinical effect and less frequent medication side effects than regular dose pregabalin (pregabalin 300 mg/day) and alpha lipoic acid. Therefore, low-dose pregabalin (pregabalin 150 mg/day) and alpha lipoic acid should be considered in treating diabetic neuropathy.

• The Korean Journal of Pain
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• v.9 no.2
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• pp.311-317
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• 1996

Background: Following peripheral nerve injury, rats will show a tactile allodynia and hyperalgesia. But the mechanism of allodynia is still obscure. Previous studies have shown this allodynia was reversed by intrathecal alpha-2 agonists and NMDA antagonists, but not by morphine. In formalin test, either the pretreatment of NMDA antagonist or morphine prevents the hyperalgesia. The present studies, using rats rendered allodynic by ligation of the left L5 and L6 nerves, aimed to investigate the effects of pretreatment of MK-801 and morphine on the development of tactile allodynia. Methods and Material: Male Sprague-Dawley rats (100~150g) were anesthetized with halothane, the left L5 and L6 spinal nerves were ligated tightly by 6-0 black silk. For sham operation muscle dissection was performed but the spinal nerve was not ligated. For pretreatment of drugs, MK-801 (NMDA antagonist; 0.3 mg/kg). CNQX (non-NMDA) antagonist; 0.3 mg/kg), morphine (1 mg/kg) or saline (placebo) was administered subcutaneously 30 minutes before operation. A second dose was administered subcutaneously 24 hours after operation and further doses were given daily for 2 days further. The volume of injection was 5 ml/kg. To assess the mechanical allodynia, paw withdrawal thresholds of ipsilateral limb were determined using 8 von Frey hairs. Results: Within 2 days saline, CNQX or morphine injected rats developed tactile allodynia (paw withdrawal threshold was about 2g), and persisted for over 2 weeks. Pretreatment of MK-801 delayed the development of tactile allodynia for 3 days comparing to that of saline injected rat. Conclusion: NMDA receptor in the central nerve system plays an important role in the development of tactile allodynia induced by peripheral nerve injury. But the mechanism may be different from hyperalgesia developed in formalin test.