Woong Mo Kim

A randomized controlled trial of intra-articular prolotherapy versus steroid injection for sacroiliac joint pain.

OBJECTIVES Controversy exists regarding the efficacy of ligament prolotherapy in alleviating sacroiliac joint pain. The inconsistent success rates reported in previous studies may be attributed to variability in patient selection and techniques between studies. It was hypothesized that intra-articular prolotherapy for patients with a positive response to diagnostic block may mitigate the drawbacks of ligament prolotherapy. The purpose of this study was to evaluate the efficacy and long-term effectiveness of intra-articular prolotherapy in relieving sacroiliac joint pain, compared with intra-articular steroid injection. DESIGN This was a prospective, randomized, controlled trial. SETTINGS/LOCATION The study was conducted at an outpatient pain medicine clinic at Chonnam National University Hospital in Gwang-ju, Korea. SUBJECTS The study included patients with sacroiliac joint pain, confirmed by ≥50% improvement in response to local anesthetic block, lasting 3 months or longer, and who failed medical treatment. INTERVENTIONS The treatment involved intra-articular dextrose water prolotherapy or triamcinolone acetonide injection using fluoroscopic guidance, with a biweekly schedule and maximum of three injections. OUTCOME MEASURES Pain and disability scores were assessed at baseline, 2 weeks, and monthly after completion of treatment. RESULTS The numbers of recruited patients were 23 and 25 for the prolotherapy and steroid groups, respectively. The pain and disability scores were significantly improved from baseline in both groups at the 2-week follow-up, with no significant difference between them. The cumulative incidence of ≥50% pain relief at 15 months was 58.7% (95% confidence interval [CI] 37.9%-79.5%) in the prolotherapy group and 10.2% (95% CI 6.7%-27.1%) in the steroid group, as determined by Kaplan-Meier analysis; there was a statistically significant difference between the groups (log-rank p < 0.005). CONCLUSIONS Intra-articular prolotherapy provided significant relief of sacroiliac joint pain, and its effects lasted longer than those of steroid injections. Further studies are needed to confirm the safety of the procedure and to validate an appropriate injection protocol.

Analgesic Effects of Intrathecal Curcumin in the Rat Formalin Test

Background Curcumin has been reported to have anti-inflammatory, antioxidant, antiviral, antifungal, antitumor, and antinociceptive activity when administered systemically. We investigated the analgesic efficacy of intrathecal curcumin in a rat model of inflammatory pain. Methods Male Sprague Dawley rats were prepared for intrathecal catheterization. Pain was evoked by injection of formalin solution (5%, 50 µl) into the hind paw. Curcumin doses of 62.5, 125, 250, and 500 µg were delivered through an intrathecal catheter to examine the flinching responses. The ED50 values (half-maximal effective dose) with 95% confidence intervals of curcumin for both phases of the formalin test were calculated from the dose-response lines fitted by least-squares linear regression on a log scale. Results In rats with intrathecal administration of curcumin, the flinching responses were significantly decreased in both phases. The slope of the regression line was significantly different from zero only in phase 2, and the ED50 value (95% confidence interval) of curcumin was 511.4 µg (23.5-1126.5). There was no apparent abnormal behavior following the administration of curcumin. Conclusions Intrathecal administration of curcumin decreased inflammatory pain in rats, and further investigation to elucidate the precise mechanism of spinal action of curcumin is warranted.

Role of neuronal nitric oxide synthase in the antiallodynic effects of intrathecal EGCG in a neuropathic pain rat model

Epigallocatechin-3-gallate (EGCG), the major catechin in green tea, is known to have antioxidant activity against nitric oxide (NO) by scavenging free radicals, chelating metal ions, and inducing endogenous antioxidant enzymes. NO and NO synthase (NOS) play an important role in nociceptive processing. In this study, we examined the effects of intrathecal EGCG in neuropathic pain induced by spinal nerve ligation and the possible involvement of NO. Intrathecal EGCG attenuated mechanical allodynia in spinal nerve ligated-rats, compared to sham-operated rats, with a maximal possible effect of 69.2%. This antinociceptive effect was reversed by intrathecal pretreatment with l-arginine, a precursor of NO. Intrathecal EGCG also blocked the increase in nNOS expression in the spinal cord of spinal nerve-ligated rats, but iNOS expression was not significantly suppressed. These findings suggest that intrathecal EGCG could produce an antiallodynic effect against spinal nerve ligation-induced neuropathic pain, mediated by blockade of nNOS protein expression and inhibition of the pronociceptive effects of NO.

Antinociceptive effect of intrathecal cannabinoid receptor agonist WIN 55,212-2 in a rat bone tumor pain model

Bone tumor pain is a poorly controlled pain comprising background and severe pain on moving or weight-bearing postures that decreases the quality of life for cancer patients; thus, more effective analgesics are clearly needed. This study evaluated the efficacy of a cannabinoid (CB) receptor agonist (WIN 55,212-2) on bone tumor pain in the spinal cords of rats, and clarified the roles of the CB1 and CB2 receptors in WIN 55,212-2-induced antinociception at the spinal level. Bone tumor pain was induced by injecting MRMT-1 tumor cells (1×10(5)) into the right tibias of female Sprague-Dawley rats under sevoflurane anesthesia. Bone tumor development was monitored radiologically. Under sevoflurane anesthesia, a polyethylene catheter was inserted into the intrathecal space for drug administration. To assess pain, the withdrawal threshold was measured by applying a von Frey filament to the tumor cell inoculation site. The effect of intrathecal WIN 55,212-2 was investigated. Next, the WIN 55,212-2-mediated antinociception was reversed using CB1 (AM 251) and CB2 (AM 630) receptor antagonists. The intratibial injection of MRMT-1 tumor cells produced radiologically confirmed bone tumors. The paw withdrawal threshold decreased significantly (mechanical allodynia) with tumor development; however, intrathecal WIN 55,212-2 dose-dependently increased the withdrawal threshold. The antinociceptive effect of WIN 55,212-2 was reversed by both CB1 and CB2 receptor antagonists. Intrathecal WIN 55,212-2 reduced bone tumor-related pain behavior mediated via spinal CB1 and CB2 receptors. Therefore, spinal CB receptor agonists may be novel analgesics in the treatment of bone tumor pain.

Urinary Trypsin Inhibitors Afford Cardioprotective Effects through Activation of PI3K-Akt and ERK Signal Transduction and Inhibition of p38 MAPK and JNK

Background: We determined the effect of urinary trypsin inhibitors (UTI) in regional myocardial ischemia/reperfusion (I/R) injury and its underlying mechanisms involving the role of prosurvival kinases such as phosphatidylinositol-3-OH kinases (PI3K)-Akt and extracellular signal-regulated kinases (ERK 1/2) and apoptotic kinases such as p38 and JNK. Methods: The rats were anesthetized and subjected to an I/R insult consisting of 30-min left anterior descending coronary artery (LAD) occlusion followed by reperfusion. Infarct size was measured after 120 min of reperfusion. UTI was given alone or along with wortmannin (inhibitor of PI3K) or PD098059 (inhibitor of ERK1/2) before LAD occlusion. The phosphorylation of Akt, ERK1/2, p38 and JNK was determined by immunoblotting after 5 min of reperfusion. UTI was administered 10 min before LAD occlusion, and wortmannin and PD098059 were administered 20 min before LAD occlusion. Results: UTI significantly reduced the infarct size compared with the control. Wortmannin or PD098059 alone did not affect the infarct size, but they abolished the UTI-induced cardioprotective effect. UTI significantly reduced the phosphorylation of p38 and JNK, while it enhanced that of Akt and ERK1/2. Conclusions: UTI has a protective effect against regional myocardial I/R injury through activation of survival kinases PI3K-Akt and ERK1/2 and attenuation of p38 and JNK.

Evaluation for the interaction between intrathecal melatonin and clonidine or neostigmine on formalin-induced nociception.

AIMS We examined the nature of pharmacological interaction after coadministration of melatonin with clonidine or neostigmine on formalin-induced nociception at the spinal level. Further, the role of melatonin receptor subtypes in melatonin-induced antinociception was clarified. MAIN METHODS Catheters were inserted into the intrathecal space of male Sprague-Dawley rats. Pain was assessed using the formalin test (induced by a subcutaneous injection of 50 microl of a 5% formalin solution to the hindpaw). Isobolographic analysis was used for the evaluation of drug interaction between melatonin and clonidine or neostigmine. Non-selective MT1/MT2 receptors antagonist (luzindole), MT2 receptor antagonist (4-P-PDOT), and MT3 receptor/alpha-1 adrenoceptor antagonist (prazosin) were intrathecally given to verify the involvement of the melatonin receptor subtypes in the antinociception of melatonin. Furthermore, the effect of intrathecal MT3 receptor ligand (GR 135531) was observed. KEY FINDINGS Intrathecal melatonin, clonidine, and neostigmine dose-dependently suppressed the flinching response during phase 1 and phase 2 in the formalin test. Isobolographic analysis showed additivity between melatonin and clonidine or neostigmine in both phases. The antinociceptive effect of melatonin was antagonized by luzindole, 4-P-PDOT, and prazosin in the spinal cord. Intrathecal GR 135531 was ineffective against the formalin-induced flinching response. SIGNIFICANCE These results suggest that melatonin interacts additively with clonidine and neostigmine in the formalin-induced nociception at the spinal level. Furthermore, the antinociception of melatonin is mediated through the MT2 receptor, but not the MT3 receptor. However, it seems that alpha-1 adrenoceptor plays in the effect of melatonin.

Antiallodynic Effect of Thalidomide and Morphine on Rat Spinal Nerve Ligation-induced Neuropathic Pain

Background Tumor necrosis factor-alpha and other proinflammatory cytokines are becoming well recognized as key mediators in the pathogenesis of many types of neuropathic pain. Thalidomide has profound immunomodulatory actions in addition to their originally intended pharmacological actions. There has been debate on the analgesic efficacy of opioids in neuropathic pain. The aim of this study was to investigate the effect of thalidomide and morphine on a spinal nerve ligation model in rats. Methods Male Sprague-Dawley rats weighing 100-120 g were used. Lumbar (L) 5 and 6 spinal nerve ligations were performed to induce neuropathic pain. For assessment of mechanical allodynia, mechanical stimulus using von Frey filament was applied to the paw to measure withdrawal threshold. The effects of intraperitoneal thalidomide (6.25, 12.5, 25 and 50 mg/kg, respectively) and morphine (3 and 10 mg/kg, respectively) were examined on a withdrawal threshold evoked by spinal nerve ligation. Results After L5 and 6 spinal nerve ligation, paw withdrawal thresholds on the ipsilateral side were significantly decreased compared with pre-operative baseline and with those in the sham-operated group. Intraperitoneal thalidomide and morphine significantly increased the paw withdrawal threshold compared to controls and produced dose-responsiveness. Conclusions Systemic thalidomide and morphine have antiallodynic effect on neuropathic pain induced by spinal nerve ligation in rat. These results suggest that morphine and thalidomide may be alternative therapeutic approaches for neuropathic pain.

Roles of opioid receptor subtypes on the antinociceptive effect of intrathecal sildenafil in the formalin test of rats

Recently, it has been known that the antinociception of sildenafil, a phosphodiesterase 5 inhibitor, is mediated through the opioid receptors. There are common three types of opioid receptors mu, delta, and kappa. We characterized the role of subtypes of opioid receptor for the antinociception of sildenafil at the spinal level. Intrathecal catheters were placed for drug delivery and formalin solution (5%, 50 microl) was injected for induction of nociception within male SD rats. The effect of mu opioid receptor antagonist (CTOP), delta opioid receptor antagonist (naltrindole), and kappa opioid receptor antagonist (GNTI) on the activity of sildenafil was examined. Intrathecal sildenafil decreased the flinching responses during phases 1 and 2 in the formalin test. Intrathecal CTOP and naltrindole reversed the antinociception of sildenafil during both phases in the formalin test. Intrathecal GNTI reversed the effect of sildenafil during phase 2, but not phase 1. These results suggest that sildenafil is effective to acute pain and the facilitated pain state at the spinal level. Both mu and delta opioid receptors are involved. However, it seems that kappa opioid receptors play in the effect of sildenafil.

Antinociceptive Effect of Memantine and Morphine on Vincristine-induced Peripheral Neuropathy in Rats

Background Vincristine-induced peripheral neuropathy is a major dose limiting side effect and thus effective therapeutic strategy is required. In this study, we investigated the antinociceptive effect of memantine and morphine on a vincristine-induced peripheral neuropathy model in rats. Methods Male Sprague-Dawley rats weighing 220-240 g were used in all experiments. Rats subsequently received daily intraperitoneal injections of either vincristine sulfate (0.1 ml/kg/day) or saline (0.1 ml/kg/day) over 12 days, immediately following behavioral testing. For assessment of mechanical allodynia, mechanical stimuli using von Frey filament was applied to the paw to measure withdrawal threshold. The effects of N-methyl-D-aspartate receptors antagonist (memantine; 2.5, 5, 10 mg/kg intraperitoneal), opioid agonist (morphine; 2.5, 5, 10 mg/kg intraperitoneal) and vehicle (saline) on vicristine-induced neuropathy were evaluated. Results Mechanical allodynia developed over the course of ten daily injections of vincristine relative to groups receiving saline at the same time. Morphine abolished the reduction in paw withdrawal threshold compared to vehicle and produced dose-responsiveness. Only the highest dose of memantine (10 mg/kg) was able to increase paw withdrawal threshold compared to vehicle. Conclusions Systemic morphine and memantine have an antinociceptive effect on the vincristine-induced peripheral neuropathy model in rats. These results suggest morphine and memantine may be an alternative approach for the treatment of vincristine-induced peripheral neuropathic pain.

Antinociceptive Effect of Intrathecal Nefopam and Interaction with Morphine in Formalin-Induced Pain of Rats

Background Nefopam, a non-opiate analgesic, has been regarded as a substance that reduces the requirement for morphine, but conflicting results have also been reported. The inhibition of monoamine reuptake is a mechanism of action for the analgesia of nefopam. The spinal cord is an important site for the action of monoamines however, the antinociceptive effect of intrathecal nefopam was not clear. This study was performed to examine the antinociceptive effect of intrathecal (i.t.) nefopam and the pattern of pharmacologic interaction with i.t. morphine in the formalin test. Methods Male Sprague-Dawley rats were implanted with an i.t. catheter, and were randomly treated with a vehicle, nefopam, or morphine. Formalin was injected into the hind-paw 10 min. after an i.t. injection of the above experiment drugs. After obtaining antinociceptive ED50 of nefopam and morphine, the mixture of nefopam and morphine was tested for the antinociceptive effect in the formalin test at a dose of 1/8, 1/4, 1/2 of ED50, or ED50 of each drug followed by an isobolographic analysis. Results Intrathecal nefopam significantly reduced the flinching responses in both phases of the formalin test in a dose-dependent manner. Its effect, however, peaked at a dose of 30 µg in phase 1 (39.8% of control) and 10 µg during phase 2 (37.6% of control). The isobolograhic analysis indicated an additive interaction of nefopam and morphine during phase 2, and a synergy effect in antinociception during phase 1. Conclusions This study demonstrated that i.t. nefopam produces an antinociceptive effect in formalin induced pain behavior during both phases of the formalin test, while interacting differently with i.t. morphine, synergistically during phase 1, and additively during phase 2.