Both nitric oxide and nitrite prevent homocysteine-induced endoplasmic reticulum stress and subsequent apoptosis via cGMP-dependent pathway in neuronal cells.

Growing evidence indicates that endoplasmic reticulum (ER) stress and/or ER stress-mediated apoptosis may play a role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease. The present study investigated the effects of non-cytotoxic concentrations of nitric oxide (NO) and nitrite, a metabolite of NO, on ER stress and ER stress-mediated apoptosis in Neuro-2a cells exposed to homocysteine (Hcy), an endogenous ER stress inducer. Hcy induced ER stress, as confirmed by inositol-requiring enzyme 1α (IRE1α) phosphorylation and X-box-binding protein-1 (Xbp1) mRNA splicing as well as C/EBP homologous protein (CHOP) expression, and apoptosis, as verified by Annexin V-positive cells. Surprisingly, non-cytotoxic NO (S-nitrosoglutathione) and nitrite markedly reduced Hcy-induced IRE1α phosphorylation, Xbp1 mRNA splicing, CHOP expression, and Annexin V-positive cells, indicating the cytoprotection of NO and nitrite against Hcy-induced ER stress and apoptosis. Moreover, inhibition of sGC/cGMP pathway abolished the cytoprotective effects of NO and nitrite, whereas cellular elevation of cGMP levels mimicked the cytoprotective actions of NO and nitrite. These findings provide the first evidence showing that both NO and nitrite can reduce ER stress and subsequent apoptosis via NO-sGC-cGMP pathway in neuronal cells and suggesting that NO and/or nitrite may have therapeutic value in the treatment of ER stress-associated neurodegenerative diseases.

Epidemiology of Postherpetic Neuralgia in Korea: An Electronic Population Health Insurance System Based Study.

Postherpetic neuralgia (PHN) is a disease entity defined as persistent pain after the acute pain of herpes zoster gradually resolves. It is associated with impaired daily activities, resulting in reduced quality of life. General epidemiological data on PHN is necessary for the effective management. However, data on the epidemiology of PHN in Korea is lacking. The aim of this study was to evaluate the epidemiological features of PHN in the general population.We used population-based medical data for 51,448,491 subscribers to the Health Insurance Service in the year of 2013 to analyze of PHN epidemiology in Korea, such as the incidence, regional distribution, seasonal variation, and healthcare resource utilization. Total number of patients and medical cost on PHN were analyzed from 2009 to 2013.Findings indicate that the incidence of PHN in Korea was 2.5 per 1000 person-years, which was strongly correlated with age and sex. There were no differences in seasonal variation or regional distribution. The medical cost increased steadily over the study period. When admitted to general hospitals, patients with PHN were mainly managed in the dermatology and anesthesiology departments.The incidence and prevalence rates of PHN in Koreans appear to be considerably higher compared to those in western populations, while the sex and age predisposition was similar. Considering that the pain associated with PHN can have a marked impact on a patient's quality of life resulting in a medicosocial economic burden, anesthesiology physicians have an important role in primary care in Korea. Future research on the cost-effectiveness of the management of PHN is needed.

Resveratrol analog piceatannol restores the palmitic acid-induced impairment of insulin signaling and production of endothelial nitric oxide via activation of anti-inflammatory and antioxidative heme oxygenase-1 in human endothelial cells.

Growing evidence suggests that the elevation of free fatty acids, including palmitic acid (PA), are associated with inflammation and oxidative stress, which may be involved in endothelial dysfunction, characterized by the reduced bioavailability of nitric oxide (NO) synthesized from endothelial NO synthase (eNOS). Heme oxygenase-1 (HO-1) is important in the preservation of NO bioavailability. Piceatannol (Pic), with similar chemical structure to resveratrol, is suggested to possess similar protective effects as resveratrol. In the present study, human umbilical vein endothelial cells (HUVECs), stimulated with PA, were used to examine the endothelial protective effects of Pic. Pic increased the expression of HO-1 via nuclear factor erythroid-2-related factor-2 activation in the HUVECs, and decreased the PA-induced secretions of interleukin-6 and tumor necrosis factor-α, and the formation of reactive oxygen species ROS via inhibition of NF-κB activation. Notably, following inhibition of HO-1 activity by tin protoporphryin-IX, Pic did not prevent cytokine secretion, ROS formation, and NF-κB activation in the PA-stimulated HUVECs. PA attenuated insulin-mediated insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation, leading to decreased glucose uptake, and phosphorylation of eNOS, leading to a reduction in the production of NO. Pic effectively mitigated the inhibitory effects of PA on the insulin-mediated phosphorylation of IRS-1 and eNOS, which was not observed following inhibition of HO­1 activity. The results of the present study suggested that Pic may have the potential to prevent PA-induced impairment of insulin signaling and eNOS function, by inducing the expression of the anti-inflammatory and antioxidant, HO-1.

Suppression of spinal connexin 43 expression attenuates mechanical hypersensitivity in rats after an L5 spinal nerve injury.

Activation of spinal astrocytes may contribute to neuropathic pain. Adjacent astrocytes can make direct communication through gap junctions formed by connexin 43 (Cx43) in the central nervous system. Yet, the role of spinal astroglial gap junctions in neuropathic pain is not fully understood. Since Cx43 is the connexin isoform expressed preferentially in astrocytes in the spinal cord, we used a small interfering RNA (siRNA) approach to examine whether suppression of spinal Cx43 expression inhibits mechanical hypersensitivity in rats after an L5 spinal nerve ligation (SNL). SNL rats were administered intrathecal Cx43 siRNA (3µg/15µl, twice/day) or an equal amount of mismatch siRNA (control) on days 14-17 post-SNL. Cx43 siRNA, but not mismatch siRNA, alleviated mechanical hypersensitivity in SNL rats. Furthermore, Western blot analysis showed that the pain inhibition induced by Cx43 siRNA correlated with downregulation of Cx43 expression, but not that of Cx36 (the neuronal gap junction protein) or glial fibrillary acidic protein (GFAP, a marker for reactive astrocytes) in the spinal cord of SNL rats. Western blot analysis and immunohistochemistry also showed that SNL increased GFAP expression, but decreased Cx43 expression, in spinal cord. Our results provide direct evidence that selective suppression of spinal Cx43 after nerve injury alleviates neuropathic mechanical hypersensitivity. These findings suggest that in the spinal cord, the enhanced function of astroglial gap junctions, especially those formed by Cx43, may be important to neuropathic pain in SNL rats.

Intrathecal carbenoxolone inhibits neuropathic pain and spinal wide-dynamic range neuronal activity in rats after an L5 spinal nerve injury.

Spinal glial gap junctions may play an important role in dorsal horn neuronal sensitization and neuropathic pain. In rats after an L5 spinal nerve ligation (SNL), we examined the effects of intrathecal injection of carbenoxolone (CBX), a gap junction decoupler, on neuropathic pain manifestations and on wide-dynamic range (WDR) neuronal activity in vivo. Intrathecal injection of CBX dose-dependently (0.1-50 µg, 10 µl) inhibited mechanical hypersensitivity in rats at 2-3 weeks post-SNL. However, the same doses of glycyrrhizic acid (an analogue of CBX that does not affect gap junctions) and mefloquine hydrochloride (a selective neuronal gap junction decoupler) were ineffective. Intrathecal CBX (5µg) also attenuated heat hypersensitivity in SNL rats. Further, rats did not develop tachyphylaxis to CBX-induced inhibition of mechanical hypersensitivity after repetitive drug treatments (25 µg/day) during days 14-16 post-SNL. Electrophysiological study in SNL rats showed that spinal topical application of CBX (100 µg, 50 µl), which mimics intrathecal drug administration, attenuated WDR neuronal responses to mechanical stimuli and to repetitive intracutaneous electrical stimuli (0.5 Hz) that induce windup, a short-form of activity-dependent neuronal sensitization. The current findings suggest that the inhibition of neuropathic pain manifestations by intrathecal injection of CBX in SNL rats may involve an inhibition of glial gap junctions and an attenuation of WDR neuronal activity in the dorsal horn.

Antidiabetic potential of the heme oxygenase-1 inducer curcumin analogues.

Although there is a therapeutic treatment to combat diabetes, the identification of agents that may deal with its more serious aspects is an important medical field for research. Diabetes, which contributes to the risk of cardiovascular disease, is associated with a low-grade chronic inflammation (inflammatory stress), oxidative stress, and endoplasmic reticulum (ER) stress. Because the integration of these stresses is critical to the pathogenesis of diabetes, agents and cellular molecules that can modulate these stress responses are emerging as potential targets for intervention and treatment of diabetic diseases. It has been recognized that heme oxygenase-1 (HO-1) plays an important role in cellular protection. Because HO-1 can reduce oxidative stress, inflammatory stress, and ER stress, in part by exerting antioxidant, anti-inflammatory, and antiapoptotic effects, HO-1 has been suggested to play important roles in pathogenesis of diabetes. In the present review, we will explore our current understanding of the protective mechanisms of HO-1 in diabetes and present some emerging therapeutic options for HO-1 expression in treating diabetic diseases, together with the therapeutic potential of curcumin analogues that have their ability to induce HO-1 expression.

The analgesic effect of nefopam with fentanyl at the end of laparoscopic cholecystectomy.

BACKGROUND: Nefopam is a centrally acting analgesic that is used to control pain. The aim of this study was to find an appropriate dose of nefopam that demonstrates an analgesic effect when administered in continuous infusion with fentanyl at the end of laparoscopic cholecystectomy. METHODS: Ninety patients scheduled for laparoscopic cholecystectomy were randomly assigned to receive analgesia with fentanyl alone (50 µg, Group 1, n = 30), or with fentanyl in combination with nefopam 20 mg (Group 2, n = 30) or in combination with nefopam 40 mg (Group 3, n = 30) at the end of surgery. Pain and side effects were evaluated at 10 minutes, 30 minutes, 1 hour, 2 hours, 6 hours, and 12 hours after arrival in the post-anesthesia care unit (PACU). RESULTS: Pain was statistically significantly lower in Groups 2 and 3 than in Group 1 at 10 minutes, 2 hours, and 6 hours after arrival in the PACU. Nausea was statistically significantly lower in Group 2 than in Groups 1 and 3 at 10 minutes after arrival in the PACU. Shivering was statistically significantly lower in Groups 2 and 3 than in Group 1 at 10 minutes after arrival in the PACU. CONCLUSIONS: Nefopam is a drug that can be safely used as an analgesic after surgery, and its side effects can be reduced when fentanyl 50 µg is injected with nefopam 20 mg.

Tolerance develops to the antiallodynic effects of the peripherally acting opioid loperamide hydrochloride in nerve-injured rats.

Peripherally acting opioids are potentially attractive drugs for the clinical management of certain chronic pain states due to the lack of centrally mediated adverse effects. However, it remains unclear whether tolerance develops to peripheral opioid analgesic effects under neuropathic pain conditions. We subjected rats to L5 spinal nerve ligation (SNL) and examined the analgesic effects of repetitive systemic and local administration of loperamide hydrochloride, a peripherally acting opioid agonist. We found that the inhibition of mechanical hypersensitivity, an important manifestation of neuropathic pain, by systemic loperamide (1.5mg/kg subcutaneously) decreased after repetitive drug treatment (tolerance-inducing dose: 0.75 to 6.0mg/kg subcutaneously). Similarly, repeated intraplantar injection of loperamide (150 µg/50 µL intraplantarly) and D-Ala(2)-MePhe(4)-Glyol(5) enkephalin (300 µg/50 µL), a highly selective mu-opioid receptor (MOR) agonist, also resulted in decreased inhibition of mechanical hypersensitivity. Pretreatment with naltrexone hydrochloride (5mg/kg intraperitoneally) and MK-801 (0.2mg/kg intraperitoneally) attenuated systemic loperamide tolerance. Western blot analysis showed that repetitive systemic administration of morphine (3mg/kg subcutaneously), but not loperamide (3mg/kg subcutaneously) or saline, significantly increased MOR phosphorylation in the spinal cord of SNL rats. In cultured rat dorsal root ganglion neurons, loperamide dose-dependently inhibited KCl-induced increases in [Ca(2+)]i. However, this drug effect significantly decreased in cells pretreated with loperamide (3 µM, 72 hours). Intriguingly, in loperamide-tolerant cells, the delta-opioid receptor antagonist naltrindole restored loperamide's inhibition of KCl-elicited [Ca(2+)]i increase. Our findings indicate that animals with neuropathic pain may develop acute tolerance to the antiallodynic effects of peripherally acting opioids after repetitive systemic and local drug administration.

Conventional and kilohertz-frequency spinal cord stimulation produces intensity- and frequency-dependent inhibition of mechanical hypersensitivity in a rat model of neuropathic pain.

BACKGROUND: Spinal cord stimulation (SCS) is a useful neuromodulatory technique for treatment of certain neuropathic pain conditions. However, the optimal stimulation parameters remain unclear. METHODS: In rats after L5 spinal nerve ligation, the authors compared the inhibitory effects on mechanical hypersensitivity from bipolar SCS of different intensities (20, 40, and 80% motor threshold) and frequencies (50, 1 kHz, and 10 kHz). The authors then compared the effects of 1 and 50 Hz dorsal column stimulation at high- and low-stimulus intensities on conduction properties of afferent Aα/ß-fibers and spinal wide-dynamic-range neuronal excitability. RESULTS: Three consecutive daily SCS at different frequencies progressively inhibited mechanical hypersensitivity in an intensity-dependent manner. At 80% motor threshold, the ipsilateral paw withdrawal threshold (% preinjury) increased significantly from pre-SCS measures, beginning with the first day of SCS at the frequencies of 1 kHz (50.2 ± 5.7% from 23.9 ± 2.6%, n = 19, mean ± SEM) and 10 kHz (50.8 ± 4.4% from 27.9 ± 2.3%, n = 17), whereas it was significantly increased beginning on the second day in the 50 Hz group (38.9 ± 4.6% from 23.8 ± 2.1%, n = 17). At high intensity, both 1 and 50 Hz dorsal column stimulation reduced Aα/ß-compound action potential size recorded at the sciatic nerve, but only 1 kHz stimulation was partially effective at the lower intensity. The number of actions potentials in C-fiber component of wide-dynamic-range neuronal response to windup-inducing stimulation was significantly decreased after 50 Hz (147.4 ± 23.6 from 228.1 ± 39.0, n = 13), but not 1 kHz (n = 15), dorsal column stimulation. CONCLUSIONS: Kilohertz SCS attenuated mechanical hypersensitivity in a time course and amplitude that differed from conventional 50 Hz SCS, and may involve different peripheral and spinal segmental mechanisms.

Pneumocephalus in a patient with no cerebrospinal fluid leakage after lumbar epidural block - a case report -.

Several complications are possible after a lumbar epidural block. However pneumocephalus are rare. In this case, we report a case of pneumocephalus. A 68-year-old male patient received lumbar epidural block with the loss of resistance technique using air, and after 35 minutes, apnea, unconsciousness, hypotension, and bradycardia occurred. Immediately, brain CT was done, and we found pneumocephalus. The patient complained of severe occipital headache and itchiness due to pneumocehalus. After conservative treatment, the patient recovered without neurologic complications, and on the seventh day of his hospitalization, he was discharged from the hospital.

Okanin, a chalcone found in the genus Bidens, and 3-penten-2-one inhibit inducible nitric oxide synthase expression via heme oxygenase-1 induction in RAW264.7 macrophages activated with lipopolysaccharide.

Excess production of nitric oxide by activated macrophages via inducible nitric oxide synthase leads to the development of various inflammatory diseases. Heme oxygenase-1 expression via activation of nuclear factor-erythroid 2-related factor 2 inhibits nitric oxide production and inducible nitric oxide synthase expression in activated macrophages. Okanin is one of the most abundant chalcones found in the genus Bidens (Asteraceae) that is used as various folk medications in Korea and China for treating inflammation. Here, we found that okanin (possessing the α-ß unsaturated carbonyl group) induced heme oxygenase-1 expression via nuclear factor-erythroid 2-related factor 2 activation in RAW264.7 macrophages. 3-Penten-2-one, of which structure, as in okanin, possesses the α-ß unsaturated carbonyl group, also induced nuclear factor-erythroid 2-related factor 2-dependent heme oxygenase-1 expression, while both 2-pentanone (lacking a double bond) and 2-pentene (lacking a carbonyl group) were virtually inactive. In lipopolysaccharide-activated RAW264.7 macrophages, both okanin and 3-penten-2-one inhibited nitric oxide production and inducible nitric oxide synthase expression via heme oxygenase-1 expression. Collectively, our findings suggest that by virtue of its α-ß unsaturated carbonyl functional group, okanin can inhibit nitric oxide production and inducible nitric oxide synthase expression via nuclear factor-erythroid 2-related factor 2-dependent heme oxygenase-1 expression in lipopolysaccharide-activated macrophages.

Mitogen-Activated Protein Kinases and Reactive Oxygen Species: How Can ROS Activate MAPK Pathways?

Mitogen-activated protein kinases (MAPKs) are serine-threonine protein kinases that play the major role in signal transduction from the cell surface to the nucleus. MAPKs, which consist of growth factor-regulated extracellular signal-related kinases (ERKs), and the stress-activated MAPKs, c-jun NH(2)-terminal kinases (JNKs) and p38 MAPKs, are part of a three-kinase signaling module composed of the MAPK, an MAPK kinase (MAP2K) and an MAPK kinase (MAP3K). MAP3Ks phosphorylate MAP2Ks, which in turn activate MAPKs. MAPK phosphatases (MKPs), which recognize the TXY amino acid motif present in MAPKs, dephosphorylate and deactivate MAPKs. MAPK pathways are known to be influenced not only by receptor ligand interactions, but also by different stressors placed on the cell. One type of stress that induces potential activation of MAPK pathways is the oxidative stress caused by reactive oxygen species (ROS). Generally, increased ROS production in a cell leads to the activation of ERKs, JNKs, or p38 MAPKs, but the mechanisms by which ROS can activate these kinases are unclear. Oxidative modifications of MAPK signaling proteins and inactivation and/or degradation of MKPs may provide the plausible mechanisms for activation of MAPK pathways by ROS, which will be reviewed in this paper.

Treatment of intractable hiccups with an oral agent monotherapy of baclofen -a case report-.

Hiccups are an involuntarily powerful spasm of the diaphragm, followed by a sudden inspiration with a closure of the glottis. Hiccups that are caused by gastric distention, spicy foods and neural dysfunction can resolve themselves without any treatment. Some hiccups are associated with certain diseases or they occur postsurgically, and life-restricting intractable hiccups should be treated. The cause of hiccups should be quickly determined so as to administer the proper treatment. Hiccups often remit spontaneously within a short period of time, but they may also occur without remission for a prolonged period in some cases. We report here on a 36-year-old man who suffered with intractable hiccups for 5 years. We administered a single oral dose of baclofen, and then the hiccups disappeared. We conclude that a single dose of baclofen is a good treatment for intractable hiccups.

Spinal cord stimulation in a patient with pain in both legs due to spinal metastasis of lung cancer: A case report.

Spinal metastasis is common in patients with cancer, as the spine is the third most common site for metastasis of lung cancer. A 58-year-old woman was suffering from pain in her both legs due to spinal metastasis of lung cancer. She was treated with various nerve blocks including lumbar epidural block, and continuous epidural block with morphine, subarachnoid alcohol block, and with opioid medication. None of these treatments were effective for the pain, but spinal cord stimulation produced excellent results.

Involvement of anti-inflammatory heme oxygenase-1 in the inhibitory effect of curcumin on the expression of pro-inflammatory inducible nitric oxide synthase in RAW264.7 macrophages.

Curcumin, at high concentrations (>2 microM), inhibits the production of nitric oxide (NO) and the expression of inducible NO synthase (iNOS) through inactivation of nuclear factor (NF)-kappaB and, at low concentrations, induces the expression of heme oxygenase (HO)-1 in macrophages. Here, we demonstrated that curcumin at low concentrations (0.5-2 microM) can also inhibit NO production and iNOS expression in lipopolysaccharide (LPS)-activated RAW264.7 macrophages only when the cells were pretreated for at least 6h with curcumin. Curcumin induced dose- and time-dependent HO-1 expression, and this was coincident with the inhibitory effects of low concentrations of curcumin on NO production and iNOS expression. Blockage of HO-1 activity or knockdown of HO-1 expression abolished the inhibitory effects of curcumin. Over-expression of HO-1 or exogenous addition of carbon monoxide, a byproduct derived from heme degradation, mimicked the inhibitory action of low concentrations of curcumin. Moreover, LPS-induced NF-kappaB was diminished in macrophages subjected to prolonged treatment with low concentrations of curcumin. Treatment with HO inhibitor abolished the inhibitory effect of curcumin on LPS-induced NF-kappaB activation. Collectively, we provide evidence to support the important role of HO-1 in inhibition of NO production and iNOS expression by curcumin even at low concentrations.