Spinal sigma-1 receptors activate NADPH oxidase 2 leading to the induction of pain hypersensitivity in mice and mechanical allodynia in neuropathic rats

We have recently demonstrated that spinal sigma-1 receptors (Sig-1Rs) mediate pain hypersensitivity in mice and neuropathic pain in rats. In this study, we examine the role of NADPH oxidase 2 (Nox2)-induced reactive oxygen species (ROS) on Sig-1R-induced pain hypersensitivity and the induction of chronic neuropathic pain. Neuropathic pain was produced by chronic constriction injury (CCI) of the right sciatic nerve in rats. Mechanical allodynia and thermal hyperalgesia were evaluated in mice and CCI-rats. Western blotting and dihydroethidium (DHE) staining were performed to assess the changes in Nox2 activation and ROS production in spinal cord, respectively. Direct activation of spinal Sig-1Rs with the Sig-1R agonist, PRE084 induced mechanical allodynia and thermal hyperalgesia, which were dose-dependently attenuated by pretreatment with the ROS scavenger, NAC or the Nox inhibitor, apocynin. PRE084 also induced an increase in Nox2 activation and ROS production, which were attenuated by pretreatment with the Sig-1R antagonist, BD1047 or apocynin. CCI-induced nerve injury produced an increase in Nox2 activation and ROS production in the spinal cord, all of which were attenuated by intrathecal administration with BD1047 during the induction phase of neuropathic pain. Furthermore, administration with BD1047 or apocynin reversed CCI-induced mechanical allodynia during the induction phase, but not the maintenance phase. These findings demonstrate that spinal Sig-1Rs modulate Nox2 activation and ROS production in the spinal cord, and ultimately contribute to the Sig-1R-induced pain hypersensitivity and the peripheral nerve injury-induced induction of chronic neuropathic pain.

Character comparison of abdomen-derived and eyelid-derived mesenchymal stem cells

OBJECTIVES

While most human adipose tissues, such as those located in the abdomen, hip and thigh, are of mesodermal origin, adipose tissues located in the face are of ectodermal origin. The present study has compared stem cell-related features of abdomen-derived adult stem cells (A-ASCs) with those of eyelid-derived adult stem cells (E-ASCs).

MATERIALS AND METHODS

Adipose tissue-derived cells were maintained in DMEM supplemented with 10% FBS. Before passage 6, cells were analysed using FACS, immunocytochemistry and quantitative real time PCR (qRT-PCR). To examine multi-differentiational potential, early passage ASCs were cultivated in each of a commercial Stempro(®) Differentiation kit.

RESULTS

Unlike fibroblast-like morphology of A-ASCs, E-ASCs had bipolar morphology. Both types of cell exhibited similar surface antigens, and neuronal cell-related genes and proteins. However, there were differences in mRNA expression levels of CD90 and CD146; neuron-specific enolase (NSE) and nuclear receptor-related protein 1 (Nurr1) were different between the two cell types. There was no difference in multi-differentiational potential between 3 E-ASCs lines, however, E-ASCs had higher expression levels of chondrocyte-related genes compared to A-ASCs. These cells underwent senescence and maintained normal karyotypes.

CONCLUSIONS

Although isolated from similar adipose tissues, both types of cells displayed many contrasting characteristics. Understanding defining phenotypes of such cells is useful for making suitable choices in differing clinical indications.

A randomized, multi-center, open-label, phase II study of once-per-cycle DA-3031, a biosimilar pegylated G-CSF, compared with daily filgrastim in patients receiving TAC chemotherapy for early-stage breast cancer

BACKGROUNDS

A pegylated form of recombinant granulocyte-colony stimulating factor (G-CSF) was developed for prophylactic use in breast cancer. The aim of this study was to evaluate the efficacy and safety of once-per-cycle DA-3031 in patients receiving chemotherapy for breast cancer.

METHODS

A total of 61 patients receiving docetaxel, doxorubicin, and cyclophosphamide (TAC) chemotherapy were randomized in cycle 1 to receive daily injections of filgrastim (100 μg/m(2)) or a single subcutaneous injection of pegylated filgrastim DA-3031 at a dose of either 3.6 mg or 6 mg.

RESULTS

The mean duration of grade 4 neutropenia in cycle 1 was comparable among the treatment groups (2.48, 2.20, and 2.05 days for filgrastim, DA-3031 3.6 mg and 6 mg, respectively; P=0.275). No statistically significant differences were observed in the incidence of febrile neutropenia between the treatment groups (9.5 %, 15.0 %, and 5.0 % for filgrastim, DA-3031 3.6 mg and 6 mg, respectively; P=0.681) in cycle 1. The incidences of adverse events attributable to G-CSF were similar among the treatment groups.

CONCLUSIONS

Fixed doses of 3.6 mg or 6 mg DA-3031 have an efficacy comparable to that of daily injections of filgrastim in ameliorating grade 4 neutropenia in patients receiving TAC chemotherapy.

Antinociceptive Effect of Cyperi rhizoma and Corydalis tuber Extracts on Neuropathic Pain in Rats

In this study, we examined the antinociceptive effect of Cyperi rhizoma (CR) and Corydalis tuber (CT) extracts using a chronic constriction injury-induced neuropathic pain rat model. After the ligation of sciatic nerve, neuropathic pain behavior such as mechanical allodynia and thermal hyperalgesia were rapidly induced and maintained for 1 month. Repeated treatment of CR or CT (per oral, 10 or 30 mg/kg, twice a day) was performed either in induction (day 0~5) or maintenance (day 14~19) period of neuropathic pain state. Treatment of CR or CT at doses of 30 mg/kg in the induction and maintenance periods significantly decreased the nerve injury-induced mechanical allodynia. In addition, CR and CT at doses of 10 or 30 mg/kg alleviated thermal heat hyperalgesia when they were treated in the maintenance period. Finally, CR or CT (30 mg/kg) treated during the induction period remarkably reduced the nerve injury-induced phosphorylation of NMDA receptor NR1 subunit (pNR1) in the spinal dorsal horn. Results of this study suggest that extracts from CR and CT may be useful to alleviate neuropathic pain.

Repetitive treatment with diluted bee venom reduces neuropathic pain via potentiation of locus coeruleus noradrenergic neuronal activity and modulation of spinal NR1 phosphorylation in rats

We previously demonstrated that a single injection of diluted bee venom (DBV) temporarily alleviates thermal hyperalgesia, but not mechanical allodynia, in neuropathic rats. The present study was designed to determine whether repetitive injection of DBV produces more potent analgesic effects on neuropathy-induced nociception and whether those effects are associated with increased neuronal activity in the locus coeruleus (LC) and with the suppression of spinal NMDA receptor NR1 subunit phosphorylation (pNR1). DBV (.25 mg/kg) was administered subcutaneously twice a day for 2 weeks beginning on day 15 post-chronic constrictive injury surgery. Pain responses were examined and potential changes in LC Fos expression and spinal pNR1 expression were determined. Repetitive DBV administration significantly reduced mechanical allodynia, as well as thermal hyperalgesia. The activity of LC noradrenergic neurons was increased and spinal pNR1 expression was significantly suppressed by repetitive DBV as compared with those of vehicle or single DBV injection. These suppressive effects of repetitive DBV on neuropathic pain and spinal pNR1 were prevented by intrathecal pretreatment of idazoxan, an alpha-2 adrenoceptor antagonist. These results indicate that repetitive DBV produces potent analgesic effects on neuropathic pain and this is associated with the activation of the LC noradrenergic system and with a reduction in spinal pNR1.

PERSPECTIVE

The results of current study demonstrate that repetitive administration of DBV significantly suppresses neuropathic pain. Furthermore, this study provides mechanistic information that repetitive treatment of DBV can produce more potent analgesic effect than single DBV treatment, indicating a potential novel strategy for the management of chronic pain.

The differential effect of intrathecal Nav1.8 blockers on the induction and maintenance of capsaicin- and peripheral ischemia-induced mechanical allodynia and thermal hyperalgesia

BACKGROUND

It has been reported that the selective blockade of Nav1.8 sodium channels could be a possible target for the development of analgesics without unwanted side effects. However, the precise role of spinal Nav1.8 in the induction and maintenance of persistent pain, e.g., mechanical allodynia (MA) and thermal hyperalgesia (TH), is not clear. We designed this study to investigate whether spinal Nav1.8 contributes to capsaicin-induced and peripheral ischemia-induced MA and TH.

METHODS

The Nav1.8 blockers, A-803467 or ambroxol, were injected intrathecally either before or after intraplantar capsaicin injection. To evaluate capsaicin-induced neuronal activation in the spinal cord, we quantified the number of Fos-immunoreactive cells in the dorsal horn. In the thrombus-induced ischemic pain model, we determined the differential effect of A-803467 on the induction phase or maintenance phase of MA.

RESULTS

Intrathecal injection of A-803467 (10, 30, 100 nmol) or ambroxol (241, 724, 2410 nmol) before intraplantar injection of capsaicin dose dependently prevented the induction of both MA and TH. However, posttreatment with A-803467 (100 nmol) and ambroxol (2410 nmol) did not reduce the MA that had already developed, but did significantly suppress capsaicin-induced TH. Moreover, the capsaicin-induced increase of spinal Fos-immunoreactive cells was significantly diminished by pretreatment, but not posttreatment with Nav1.8 blockers. In thrombus-induced ischemic pain rats, repetitive treatments of A-803467 during the induction period also prevented the development of MA, whereas A-803467 treatments during the maintenance period were ineffective in preventing or reducing MA.

CONCLUSIONS

These results demonstrate that spinal activation of Nav1.8 mediates the early induction of MA, but not the maintenance of MA. However, both the induction and maintenance of TH are modulated by the intrathecal injection of Nav1.8 blockers. These findings suggest that early treatment with a Nav1.8 blocker can be an important factor in the clinical management of chronic MA associated with inflammatory and ischemic pain.

Chemical stimulation of the ST36 acupoint reduces both formalin-induced nociceptive behaviors and spinal astrocyte activation via spinal alpha-2 adrenoceptors

Spinal astrocytes have emerged as important mechanistic contributors to pathological and chronic pain. Recently, we have demonstrated that injection of diluted bee venom (DBV) into the Zusanli (ST36) acupoint produces a potent anti-nociceptive effect via the activation of spinal alpha-2 adrenoceptors. However, it is unclear if this anti-nociceptive effect is associated with alterations in spinal astrocytes. Thus, the present study was designed to determine: (1) whether DBV's anti-nociceptive effect in the formalin test involves suppression of spinal astrocyte activation; (2) whether DBV-induced astrocyte inhibition is mediated by spinal alpha-2 adrenoceptors; and (3) whether this glial modulation is potentiated by intrathecal administration of the glial metabolic inhibitor, fluorocitrate (FC) in combination with DBV injection. DBV was injected directly into the ST36 acupoint, and spinal expression of the astrocytic marker, glial fibrillary acidic protein (GFAP), was assessed together with effects on formalin-induced nociception. DBV treatment reduced pain responses in the late phase of the formalin test and significantly blocked the formalin-evoked increase in spinal GFAP expression. These effects of DBV were prevented by intrathecal pretreatment with selective alpha-2A and alpha-2C adrenoceptor antagonists. Moreover, low dose intrathecal injection of FC in conjunction with low dose DBV injection into the ST36 acupoint synergistically suppressed pain responses and GFAP expression. These results demonstrate that DBV stimulation of the ST36 acupoint inhibits the formalin-induced activation of spinal astrocytes and nociceptive behaviors in this inflammatory pain model and this inhibition is associated with the activation of spinal alpha-2 adrenoceptors.

Spinal neuronal NOS activation mediates sigma-1 receptor-induced mechanical and thermal hypersensitivity in mice: involvement of PKC-dependent GluN1 phosphorylation

BACKGROUND AND PURPOSE We recently demonstrated that activation of the spinal sigma-1 receptor induces mechanical and thermal hypersensitivity via calcium-dependent second messenger cascades and phosphorylation of the spinal NMDA receptor GluN1 subunit (pGluN1). Here we examined the role of NO in this process, as it plays a critical role in PKC-mediated calcium signalling and the potentiation of NMDA receptor function. EXPERIMENTAL APPROACH The effects of intrathecal (i.t.) pretreatment with nNOS inhibitors on PRE084 (sigma-1 receptor agonist)-induced pain were assessed in mice by use of mechanical allodynia and thermal hyperalgesia tests. Western blot analysis, immunoprecipitation and immunohistochemical techniques were used to determine effects of these treatments on spinal pGluN1-immunoreactive (ir) cells, whether PRE084 induces a time-dependent modification of nNOS activity in the dorsal horn, and if any changes in nNOS activity can be blocked by sigma-1 receptor, calcineurin or soluble guanylyl cyclase (sGC) inhibitors. KEY RESULTS PRE084, injected i.t., induced mechanical and thermal hypersensitivity, and increased the number of PKC- and PKA-dependent pGluN1-ir cells in spinal cord. This PRE084-induced hypersensitivity and increase in PKC-dependent pGluN1 expression were blocked by pretreatment with N(G) -nitro-L-arginine methyl ester (L-NAME) or 7-nitroindazole (7-NI). PRE084 also time-dependently decreased the ratio of phosphorylated nNOS (pnNOS) to nNOS expression and the number of spinal pnNOS-ir cells. This decrease in pnNOS was prevented by BD1047, a sigma-1 receptor antagonist and cyclosporin A, a calcineurin inhibitor, but not by a sGC inhibitor. CONCLUSIONS AND IMPLICATIONS Spinal sigma-1 receptor-induced sensitization is mediated by an increase in nNOS activity, which is associated with an NO-induced increase in PKC-dependent pGluN1 expression.

Acidic pH facilitates peripheral αβmeATP-mediated nociception in rats: differential roles of P2X, P2Y, ASIC and TRPV1 receptors in ATP-induced mechanical allodynia and thermal hyperalgesia

Peripheral ischemia is commonly associated with an increase in tissue ATP concentration and a decrease in tissue pH. Although in vitro data suggest that low tissue pH can affect ATP-binding affinities to P2 receptors, the mechanistic relationship between ATP and low pH on peripheral nociception has not been fully examined. This study was designed to investigate the potential role of an acidified environment on intraplantar αβmeATP-induced peripheral pain responses in rats. The mechanical allodynia (MA) produced by injection of αβmeATP was significantly increased in animals that received the drug diluted in pH 4.0 saline compared to those that received the drug diluted in pH 7.0 saline. Moreover, animals injected with αβmeATP (100 nmol) in pH 4.0 saline developed thermal hyperalgesia (TH), which did not occur in animals treated with αβmeATP diluted in pH 7.0 saline. To elucidate which receptors were involved in this pH-related facilitation of αβmeATP-induced MA and TH, rats were pretreated with PPADS (P2 antagonist), TNP-ATP (P2X antagonist), MRS2179 (P2Y1 antagonist), AMG9810 (TRPV1 antagonist) or amiloride (ASIC blocker). Both PPADS and TNP-ATP dose-dependently blocked pH-facilitated MA, while TH was significantly reduced by pre-treatment with MRS2179 or AMG9810. Moreover, amiloride injection significantly reduced low pH-induced facilitation of αβmeATP-mediated MA, but not TH. These results demonstrate that low tissue pH facilitates ATP-mediated MA via the activation of P2X receptors and ASICs, whereas TH induced by ATP under low pH conditions is mediated by the P2Y1 receptor and TRPV1, but not ASIC. Thus distinct mechanisms are responsible for the development of MA and TH under conditions of tissue acidosis and increased ATP.

An increase in spinal dehydroepiandrosterone sulfate (DHEAS) enhances NMDA-induced pain via phosphorylation of the NR1 subunit in mice: involvement of the sigma-1 receptor

Our laboratory has recently demonstrated that an increase in the spinal neurosteroid, dehydroepiandrosterone sulfate (DHEAS) facilitates nociception via the activation of sigma-1 receptors and/or the allosteric inhibition GABA(A) receptors. Several lines of evidence have suggested that DHEAS positively modulates N-methyl-d-aspartate (NMDA) receptor activity within the central nervous system. Moreover, we have demonstrated that the activation of sigma-1 receptors increases NMDA receptor activity. Since NMDA receptors play a key role in the enhancement of pain perception, the present study was designed to determine whether spinally administered DHEAS modulates NMDA receptor-mediated nociceptive activity and whether this effect is mediated by sigma-1 or GABA(A) receptors. Intrathecal (i.t.) DHEAS was found to significantly potentiate i.t. NMDA-induced spontaneous pain behaviors. Subsequent immunohistochemical analysis demonstrated that i.t. DHEAS also increased protein kinase C (PKC)- and protein kinase A (PKA)-dependent phosphorylation of the NMDA receptor subunit NR1 (pNR1), which was used as a marker of NMDA receptor sensitization. The sigma-1 receptor antagonist, BD-1047, but not the GABA(A) receptor agonist, muscimol, dose-dependently suppressed DHEAS's facilitatory effect on NMDA-induced nociception and pNR1 expression. In addition, pretreatment with either a PKC or PKA blocker significantly reduced the facilitatory effect of DHEAS on NMDA-induced nociception. Conversely the GABA(A) receptor antagonist, bicuculline did not affect NMDA-induced pain behavior or pNR1 expression. The results of this study suggest that the DHEAS-induced enhancement of NMDA-mediated nociception is dependent on an increase in PKC- and PKA-dependent pNR1. Moreover, this effect of DHEAS on NMDA receptor activity is mediated by the activation of spinal sigma-1 receptors and not through the inhibition of GABA(A) receptors.

Deuterium nuclear magnetic resonance investigation of the effects of proteins and polypeptides on hydrocarbon chain order in model membrane systems

Deuterium Fourier-transform nuclear magnetic resonance spectra have been obtained of 1-myristoyl 2-(14,14,14-trideutero)myristoyl phosphatidylcholine bilayers at 34.1 MHz by using the quadrupole echo pulse technique. Thereby, we have investigated the effects upon the deuterated dimyristoyl phosphatidylcholine bilayers of the following proteins and polypeptides: gramicidin A, bacteriophage f1 coat protein, beef brain myelin proteolipid apoprotein, cytochrome b(5), and cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). Above T(c), the transition temperature between the gel and liquid crystal phases, the quadrupole splitting of the deuterium-labeled methyl group is reduced or collapsed in the presence of protein or polypeptide. No evidence has been found for ordered "boundary lipid." Below T(c), the spectra show that the hydrocarbon chains are prevented from crystallizing by the protein (or polypeptide) incorporated in the membrane. Similar disordering effects above T(c) are also seen when an unsaturated lipid, 1-(16,16,16-trideutero)palmitoyl 2-palmitoleyl phosphatidylcholine is complexed with cytochrome oxidase.

Sigma-1 receptor-induced increase in murine spinal NR1 phosphorylation is mediated by the PKCalpha and epsilon, but not the PKCzeta, isoforms

Our previous studies have demonstrated that intrathecal (i.t.) administration of a sigma-1 receptor agonist facilitated peripheral nociception via calcium-dependent second messenger cascades including protein kinase C (PKC). We also showed that activation of spinal sigma-1 receptors increased the phosphorylation of the NMDA receptor NR1 subunit (pNR1) in the spinal cord dorsal horn, which resulted in the potentiation of NMDA receptor function. The present study was designed to examine the effect of different PKC isoform inhibitors on sigma-1 receptor-mediated pain facilitation and increased spinal pNR1 expression in mice. The intrathecal injection of the sigma-1 receptor agonist, PRE-084 (PRE, 3nmol/5mul) increased the frequency of paw withdrawal responses to mechanical stimuli (0.6g) and the number of spinal pNR1-immunoreactive (ir) cells. Intrathecal pretreatment with inhibitors (Go6976, PKCepsilonV1-2 or PKC zetapseudosubstrate) of the PKCalpha, epsilon or zeta isoforms significantly reduced the PRE-induced pain facilitatory effect. On the other hand, the PRE-induced increase in the number of spinal pNR1-ir neurons was only blocked by inhibitors of the PKCalpha and PKCepsilon isoforms, but not the PKCzeta isoform. These findings demonstrate that the sigma-1 receptor-induced increase in spinal pNR1 expression is mediated by the PKCalpha and PKC epsilon isoforms, which in turn contribute to the pain facilitation phenomenon. Conversely, the sigma-1 receptor activation of the PKCzeta isoform appears to be involved in a pain signaling pathway that is independent of spinal pNR1 modulation.

Peripheral acid-sensing ion channels and P2X receptors contribute to mechanical allodynia in a rodent thrombus-induced ischemic pain model

We have previously established a thrombus-induced ischemic pain (TIIP) model in the rat, which mimics the pathophysiology of ischemic pain in patients with peripheral arterial disease. Because ischemia commonly induces acidosis and ATP release, one of the goals of this study was to investigate the role of acid-sensing ion channels (ASICs), transient receptor potential vanilloid-1 (TRPV1) receptors, and P2X receptors in the maintenance of ischemia-induced mechanical allodynia (MA). To test this, amiloride (an ASIC blocker), AMG-9810 (a TRPV1 blocker), or PPADS (a P2Xs antagonist) was intraplantarly injected at day 3 after FeCl(2) application onto the femoral artery. Ipsilateral administration of amiloride or PPADS but not AMG-9810 dose-dependently reduced MA. However, contralateral amiloride or PPADS did not suppress contralateral MA. Interestingly, co-administration of submaximal doses of amiloride and PPADS produced a significantly prolonged suppression of MA. Furthermore, ipsilateral EGTA (a calcium chelator) or chelerythrine (a protein kinase C inhibitor) also significantly reduced MA. Collectively, these findings suggest that peripheral ASICs and P2X receptors are involved in the maintenance of TIIP, which is possibly mediated by a Ca(2+)-protein kinase C signaling mechanism. These results provide mechanistic information about peripheral ischemic nociception that may be useful for developing better therapeutic management of ischemic pain in patients with peripheral arterial disease.

PERSPECTIVE

The results of the current study demonstrate that peripheral administration of an ASICs blocker or P2X antagonist significantly suppress TIIP. Co-administration of submaximal doses of ASIC and P2X antagonists produced an even greater effect. These results implicate peripheral ASICs and P2X receptors in the maintenance of thrombus-induced ischemic pain.

The anti-arthritic effect of ursolic acid on zymosan-induced acute inflammation and adjuvant-induced chronic arthritis models

Ursolic acid (UA) is pentacyclic triterpenoic acid that naturally occurs in many medicinal herbs and plants. In this study, we examined the possible suppressive effect of UA extracted from Oldenlandia diffusa on zymosan-induced acute inflammation in mice and complete Freund's adjuvant (CFA)-induced arthritis in rats. UA treatment (per oral) dose-dependently (25–200 mg kg−1) suppressed zymosan-induced leucocyte migration and prostaglandin E2 (PGE2) production in the air pouch exudates. Since the maximal effective dose of UA was 50 mg kg−1 in the zymosan experiment, we used this dose of UA in a subsequent study using an adjuvant-induced rheumatoid arthritis model. UA treatment (50 mg kg−1, per oral, once a day for 10 days) was started from day 12 after adjuvant injection. UA dramatically inhibited paw swelling, plasma PGE2 production and radiological changes in the joint caused by CFA injection. Moreover, UA significantly suppressed the arthritis-induced mechanical and thermal hyperalgesia as well as the spinal Fos expression, as determined by immunohistochemistry, which was increased by CFA injection. In addition, overall anti-arthritic potency of UA was comparable with ibuprofen (100 mg kg−1, oral) while UA did not induce significant gastric lesions as compared with the ibuprofen treatment group. These findings strongly suggest that UA is a useful suppressive compound for rheumatoid arthritis treatment with low risk of gastric problems.

Intrathecal injection of the neurosteroid, DHEAS, produces mechanical allodynia in mice: involvement of spinal sigma-1 and GABA receptors

BACKGROUND AND PURPOSE

The neurosteroid, dehydroepiandrosterone sulphate (DHEAS) and its non-sulphated form, DHEA, are considered as crucial endogenous modulators of a number of important physiological events. Evidence suggests that DHEAS and DHEA modulate central nervous system-related functions by activating sigma-1 receptors and/or allosterically inhibiting gamma-aminobutyric acid receptor type A (GABA(A)) receptors. As both the sigma-1 receptor and the GABA(A) receptor play important roles in spinal pain transmission, the present study was designed to examine whether intrathecally injected DHEAS or DHEA affect nociceptive signalling at the spinal cord level.

EXPERIMENTAL APPROACH

We first determined whether intrathecal (i.t.) DHEA or DHEAS injection was able to affect nociceptive thresholds to peripheral mechanical stimulation and subsequently examined whether this effect was mediated by sigma-1 or the GABA(A) receptors.

KEY RESULTS

The i.t. DHEAS injection dose-dependently decreased the nociceptive threshold to mechanical stimulation, thus producing mechanical allodynia. Moreover, this DHEAS-induced mechanical allodynia was significantly reduced by administration of the sigma-1 receptor antagonist, BD-1047 or the GABA(A) receptor agonist, muscimol. Conversely, i.t. DHEA had no effect on mechanical sensitivity. However, when i.t. DHEA was combined with the GABA(A) receptor antagonist bicuculline, DHEA dose-dependently produced mechanical allodynia similar to that of DHEAS. This effect was blocked by BD-1047 and by muscimol.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that i.t. injection of DHEAS produces mechanical allodynia and that the development of this mechanical allodynia is mediated by sigma-1 and GABA(A) receptors. The findings of this study raise several interesting questions for further investigations into the mechanisms underlying neurosteroid modulation of spinal pain transmission.

Three point method to characterize low-pressure electronegative discharges using electrostatic probe

Electrostatic probe measurements for low-pressure inductively coupled SF(6) plasmas are performed. From the current-voltage (I-V) curves of probe, the saturation currents of the positive ions and electrons and the electron temperature are measured. The electronegativity and the negative ion density are deduced by using the ratios of these parameters at three adjacent pressure points. The positive ion density is calculated by the orbital-motion-limited theory, and the electron temperatures are given either by the slope of the I-V curves or by the electron energy distribution function with the second derivative of I-V curves. The variations in the charged species density with pressure and power are investigated.

The anti-arthritic effect of ursolic acid on zymosan-induced acute inflammation and adjuvant-induced chronic arthritis models

Ursolic acid (UA) is pentacyclic triterpenoic acid that naturally occurs in many medicinal herbs and plants. In this study, we examined the possible suppressive effect of UA extracted from Oldenlandia diffusa on zymosan-induced acute inflammation in mice and complete Freund's adjuvant (CFA)-induced arthritis in rats. UA treatment (per oral) dose-dependently (25-200 mg kg(-1)) suppressed zymosan-induced leucocyte migration and prostaglandin E2 (PGE(2)) production in the air pouch exudates. Since the maximal effective dose of UA was 50 mg kg(-1) in the zymosan experiment, we used this dose of UA in a subsequent study using an adjuvant-induced rheumatoid arthritis model. UA treatment (50 mg kg(-1), per oral, once a day for 10 days) was started from day 12 after adjuvant injection. UA dramatically inhibited paw swelling, plasma PGE(2) production and radiological changes in the joint caused by CFA injection. Moreover, UA significantly suppressed the arthritis-induced mechanical and thermal hyperalgesia as well as the spinal Fos expression, as determined by immunohistochemistry, which was increased by CFA injection. In addition, overall anti-arthritic potency of UA was comparable with ibuprofen (100 mg kg(-1), oral) while UA did not induce significant gastric lesions as compared with the ibuprofen treatment group. These findings strongly suggest that UA is a useful suppressive compound for rheumatoid arthritis treatment with low risk of gastric problems.

Low-frequency electroacupuncture suppresses zymosan-induced peripheral inflammation via activation of sympathetic post-ganglionic neurons

Electroacupuncture (EA) is used to treat a variety of inflammatory diseases; however, the neurophysiological mechanisms underlying EA's anti-inflammatory effect remain unclear. Accumulating evidence suggests that the sympathetic nervous system regulates immunologic and inflammatory responses and thus we hypothesized that this system could be involved in EA's anti-inflammatory effect (EA-AI). The goal of the present study was to evaluate whether the sympathetic nervous system plays a critical role in EA-AI using a mouse air pouch inflammation model. We found that bilateral low-frequency (1 Hz) EA applied to the Zusanli acupoint significantly suppressed the number of zymosan-induced leukocytes migrating into the air pouch. Furthermore, double-labeling immunohistochemical experiments showed that EA stimulation increased Fos expression in choline acetyltransferase (ChAT)-positive sympathetic pre-ganglionic neurons in the intermediolateral region of thoracic spinal cord segments. Chemical sympathetic denervation by intraperitoneal injection of 6-hydroxydopamine (which spares sympathetic adrenal medullary innervation) significantly inhibited EA-AI. In contrast, adrenalectomy did not alter EA-AI. Finally, systemic propranolol administration significantly inhibited EA's anti-inflammatory effect, suggesting that beta-adrenoceptors are involved. Collectively, these results suggest that EA produces an anti-inflammatory effect in this mouse air pouch model by activating the sympathetic nervous system leading to the release of catecholamines from post-ganglionic nerve terminals, which act on beta-adrenoceptors on immune cells to inhibit their migration.

The origin of the triploid in Paragonimus westermani on the basis of variable regions in the mitochondrial DNA

Triploid, parthenogenetic forms of the lungfluke, Paragonimus westermani, occur in Japan, Korea and China. The origin(s) of triploidy has been debated over the years. Sequences of two regions in the mitochondrial DNA, i.e. partial lrRNA (16S), and a portion of the non-coding region, were obtained from natural populations of P. westermani. All triploid individuals (Japan, Korea, China) and a single tetraploid individual (China) had identical sequences in the 16S region studied. Some sequence variation was observed among diploids, with those from Taiwan being distinct from the remainder. Both neighbour joining and parsimony trees using the 16S region placed diploid individuals from southwestern Japan close to the triploids and the tetraploid. The fragment amplified from the mitochondrial non-coding region showed dimorphism. One form (type A) consisted of 239 bp comprising two identical tracts of 70 bp separated by a tract of 93 bp. The second form (Type B) consisted of only a single 70 bp tract. All diploid individuals from Taiwan, China and Korea possessed type A, while those from Japan were polymorphic; individuals from Oita and Hyogo had type B, those from Chiba had type A, but both types were found in Mie. On the other hand, all of the triploid individuals and two tetraploid individuals possessed type B. Both the form present in the non-coding region and the 16S sequence suggest an affinity between a south-eastern group of diploid populations in Japan and the triploid form. A possible mechanism responsible for the origin of the triploid is discussed.

Comparative study on biologic and immunologic characteristics of the pancreas islet cell between 24 degrees C and 37 degrees C culture in the rat

The aim of this study was to investigate the effect of culture at 24 degrees C on cell viability, cellular function, immunogenicity, and cytokine profiles of rat pancreatic islets. Pancreatic islets were isolated from Lewis rats and cultured at either 24 degrees C or 37 degrees C for 14 days. Islet recovery was counted as islet equivalents; islet viability was examined with fluorescent vital staining. Islet function was measured with a glucose stimulation test. Annexin V, and MHC class I and II expression were measured using flow cytometric assay for apoptosis and immunogenicity, respectively. Lymphocyte cell proliferation was examined with WST-1 proliferation assay. Cytokine profiles were analyzed with quantitative real time RT-PCR. All these parameters were measured on 1, 3, 5, 7 and 14 culture days after islet isolation. Islet recovery was higher in islets cultured at 24 degrees C than 37 degrees C without a change in viability. Insulin secretion after glucose stimulation was more effective in 24 degrees C culture conditions. Decreased apoptotic cell death was demonstrated in 24 degrees C cultured islets. Both MHC class I and II expression on islets and lymphocyte proliferation upon coculture with islets were less prominent in 24 degrees C cultured islets. TNF-alpha expression was lower in islets cultured at 24 degrees C than in islets cultured at 37 degrees C. Both IL-1beta and IL-10 cytokine expressions were similar under both culture conditions. This study demonstrated that cell recovery and function are increased in islets cultured at 24 degrees C than those at 37 degrees C with decreased antigenicity and proinflammatory cytokine expression.