Selegiline Modulates Lipid Metabolism by Activating AMPK Pathways of Epididymal White Adipose Tissues in HFD-Fed Obese Mice.

Obesity, as a major cause of many chronic diseases such as diabetes, cardiovascular disease, and cancer, is among the most serious health problems. Increased monoamine oxidase (MAO) activity has been observed in the adipose tissue of obese humans and animals. Although previous studies have already demonstrated the potential of MAO-B inhibitors as a treatment for this condition, the mechanism of their effect has been insufficiently elucidated. In this study, we investigated the anti-obesity effect of selegiline, a selective MAO-B inhibitor, using in vivo animal models. The effect was evaluated through an assessment of body energy homeostasis, glucose tolerance tests, and biochemical analysis. Pharmacological inhibition of MAO-B by selegiline was observed to reduce body weight and fat accumulation, and improved glucose metabolism without a corresponding change in food intake, in HFD-fed obese mice. We also observed that both the expression of adipogenenic markers, including C/EBPα and FABP4, and lipogenic markers such as pACC were significantly reduced in epididymal white adipose tissues (eWATs). Conversely, increased expression of lipolytic markers such as ATGL and pHSL and AMPK phosphorylation were noted. Treating obese mice with selegiline significantly increased expression levels of UCP1 and promoted eWAT browning, indicating increased energy expenditure. These results suggest that selegiline, by inhibiting MAO-B activity, is a potential anti-obesity treatment.

The Peripheral Role of CCL2 in the Anti-Nociceptive Effect of Sigma-1 Receptor Antagonist BD1047 on Inflammatory Hyperalgesia in Rats.

Our recent study demonstrated that the CC-chemokine ligand 2 (CCL2) present in primary afferent fibers (PAFs) plays an important role in the microglia-dependent neuronal activation associated with zymosan-induced inflammatory pain. The present study was aimed to evaluate whether BD1047 (a prototypical sigma-1 receptor (Sig-1R) antagonist) is capable of modifying elevated levels of inflammation-evoked CCL2 as a peripheral antinociceptive mechanism. In DRG primary culture, zymosan dose-dependently increased CCL2 release from isolectin B4 (IB4)-positive DRG neurons, a process that was inhibited by co-culture with BD1047. Single treatment of BD1047 before intraplantar injection of zymosan in rats significantly reduced thermal hyperalgesia and mechanical hyperalgesia, as well as CCL2 expression in DRG neurons and microglia activation in the spinal dorsal horn. In the Complete Freund's adjuvant (CFA)-induced inflammation model, repeated administration of BD1047 dramatically attenuated thermal hyperalgesia and mechanical hyperalgesia, and significantly diminished CCL2 immunoreactivity and microglia activation. Notably, CFA-induced inflammation significantly increased Sig-1R immunoreactivity in DRG neurons, which was co-localized with CCL2 and IB4, respectively. Taken together, our results suggest that BD1047's anti-nociceptive property was substantially mediated by the inhibition of CCL2 release in unmyelinated PAFs and that this may, in turn, have attenuated the spinal microglia activation that is associated with inflammatory pain.

Extract of Triticum aestivum Sprouts Suppresses Acetaminophen-Induced Hepatotoxicity in Mice by Inhibiting Oxidative Stress.

Wheat (Triticum aestivum L.) is the oldest known food crop, and many studies have reported that wheat shoots (i.e., wheatgrass) possess anti-cancer, anti-inflammatory, and antioxidant activities. However, the potentially ameliorative effect of wheat shoots on hepatotoxicity caused by high doses of N-acetyl-para-aminophenol (acetaminophen, APAP) has yet to be reported. C57BL/6 mice received daily oral TAE (100 or 200 mg/kg), positive control (silymarin 100 mg/kg), or negative control (saline vehicle) treatments for 7 days prior to intraperitoneal APAP injection. Histological, serum (ELISA), Western blotting, and quantitative PCR analyses of excised liver tissues were then performed. Pre-treatment with TAE (100 or 200 mg/kg) ameliorated APAP-induced pathological damage (i.e., hepatotoxic lesions), reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and also ameliorated APAP-induced increases in oxidative stress, thereby inhibiting oxidative liver damage and reducing the expression of inflammatory cytokines. In addition, TAE pre-treatment inhibited the expression of Cytochrome P4502E1 (CYP2E1), which is a key enzyme in the onset of APAP-induced hepatotoxicity, suppressed the expression of the target proteins regulated by the antioxidant enzyme Nrf2, and suppressed hepatocyte apoptosis. These findings suggest that TAE is an attractive therapeutic candidate that exhibits potential hepatoprotective activity by inhibiting oxidative stress, inflammation, apoptosis, and liver damage.

The CCL2 elevation in primary afferent fibers produces zymosan-induced hyperalgesia through microglia-mediated neuronal activation in the spinal dorsal horn.

Although C-C motif chemokine ligand 2 (CCL2) plays a critical role in the pathogenesis of neuropathic pain through neuron-microglia interactions, its pronociceptive function underlying inflammatory pain remains to be fully understood. The present study aimed to elucidate the potential role of CCL2 in pain sensitization following zymosan-induced inflammation. Intraplantar injection of zymosan into the rat hind paw significantly increased the expression of CCL2 in both dorsal root ganglions and the superficial dorsal horn. The expression of CCL2 was exclusively present in the isolectin B4-positive unmyelinated primary afferent fibers, but no in other cells of the spinal cord. Intrathecal administration of RS504393 (a CCR2 antagonist) markedly reduced the zymosan-induced thermal and mechanical hyperalgesia accompanied with reduced expression in the spinal cord of c-Fos, CD11b, phosphorylated p38 mitogen activated protein kinases (p-p38), and interleukin-1ß. Whole cell patch-clamp recordings on spinal cord slices further revealed that the incubation of CCL2 evoked an evident inward current in substantia gelatinosa neurons and increased level of p-p38 in microglia. Moreover, co-incubation with minocycline (an inhibitor of microglial activation) prevented CCL2-mediated activation in the spinal cord slice. Taken together, we propose that the increased CCL2 expression from primary afferent fibers following zymosan-induced inflammation activates nociceptive neurons in the spinal dorsal horn via a microglia-dependent mechanism.

The spinal antinociceptive mechanism determined by systemic administration of BD1047 in zymosan-induced hyperalgesia in rats.

Although sigma-1 receptor (Sig-1R) antagonists have a potential antinociceptive effect in inflammatory diseases, the precise mechanism is not fully understood. The present study was aimed to elucidate the role of spinal neurons and microglia in the anti-nociceptive mechanism of BD1047 (a prototypical Sig-1R antagonist) using an inflammatory pain model based on intraplantar injection of zymosan. Oral pretreatment with BD1047 dose-dependently reduced zymosan-induced thermal and mechanical hyperalgesia as well as spinal neuronal activation including increased immunoreactivity of Fos, protein kinase C (PKC) and 'PKC-dependent phosphorylation of the NMDA receptor subunit 1' (pNR1). Zymosan also led to increased CD11b immunoreactivity (a marker of microglia) accompanied by 'phosphorylated p38 mitogen activated protein kinase' (p-p38MAPK) and interleukin-1ßimmunoreactivity in the spinal dorsal horn. Intrathecal injection of a microglia modulator (minocycline), p38MAPK inhibitor (SB203580) or interleukin-1ßneutralizing antibody significantly attenuated zymosan-induced hyperalgesia. Specifically, oral pretreatment with BD1047 reduced the immunoreactivity of CD11b, p-p38MAPK and interleukin-1ß. In the spinal cord section, Sig-1R immunoreactivity was exclusively distributed in both spinal dorsal horn neurons and central endings of unmyelinated primary afferent fibers but not in glia. Intrathecal injection of BD1047 alleviated zymosan-induced hyperalgesia up to the level of oral administration. Taken together, our data imply that antinociceptive effect induced by oral treatment with BD1047 may be mediated, at least in part, by the inhibition of neuronal and microglial activation in the spinal cord triggered by inflammatory conditions.

Regulatory effect of bee venom on methamphetamine-induced cellular activities in prefrontal cortex and nucleus accumbens in mice.

Our previous studies demonstrated that subcutaneous injection of bee venom (BV) into the Zusanli (ST36) acupuncture point, namely BV acupuncture, dose-dependently prevents conditioned place preference (CPP) induced by repeated injection of methamphetamine (METH) in mice. To expand on our observations, the present study was designed to determine the suppressive mechanisms of BV acupuncture in the development of METH-induced CPP by evaluating the changes in expression of ΔFosB, phosphorylated extracellular signal-regulated kinase 1/2 (pERK), and phosphorylated calcium/calmodulin-dependent protein kinase type II (pCaMKII) in the prefrontal cortex (PFC) and nucleus accumbens (NAc) in mice. Pre-emptive treatment with BV at 30 min before repeated METH injection completely suppressed acquisition of CPP at the day 7 test session. METH-induced upregulation of ΔFosB and pERK in PFC and NAc was significantly reduced by BV pretreatment. Expression of pCaMKII was significantly elevated by METH in NAc and reduced in PFC. BV pretreatment reversed the changes of pCaMKII expression in PFC and NAc. These findings suggest that BV acupuncture may exert a suppressive effect on METH-induced addiction via regulation of signaling cascades of ΔFosB, ERK, and CaMKII in PFC and NAc.

Inhibition of mitogen-activated protein kinases phosphorylation plays an important role in the anti-nociceptive effect of pregabalin in zymosan-induced inflammatory pain model.

Although pregabalin has been shown to have preclinical and clinical efficacy in neuropathic pain, the mechanism of its antinociceptive action is still unknown in other pain states. This study aimed to evaluate the antinociceptive effect of pregabalin and its underlying spinal mechanisms related to mitogen activated protein kinases (MAPKs) in neuron and microglia following intraplantar injection of zymosan model. Zymosan evoked thermal hyperalgesia, mechanical hyperalgesia, and mechanical allodynia starting from 1 h and persistent until 5 h post-injection, which were dose-dependently reversed by oral pretreatment of pregabalin (3, 10, and 30 mg/kg). Pregabalin dramatically inhibited zymosan-induced Fos expression (a marker for neuronal activation) and microglia activation (using markers CD11b and ED1) in the spinal dorsal horn. Moreover, zymosan significantly increased phosphorylation of extracellular signal-regulated protein kinase (ERK) 1/2 (double labeling with neuron), ERK5 (double labelling with neuron and microglia) and p38 MAPK (double labeling with microglia) in the spinal dorsal horn, which overall elevations were reversed by pregabalin. These findings suggest that blockage of MAPKs activation in neuron and microglia might be closely related to the antinociceptive effect of pregabalin on zymosan-induced peripheral inflammatory pain.

Chronic activation of sigma-1 receptor evokes nociceptive activation of trigeminal nucleus caudalis in rats.

Primary headache disorders, including migraine, are thought to be mediated by prolonged nociceptive activation of the trigeminal nucleus caudalis (TNC), but the precise mechanisms are poorly understood. Our past studies demonstrated that sigma-1 receptors (Sig-1R) facilitate spinal nociceptive transmission in several pain models. Based on these findings, this study asked if chronic activation of Sig-1R by intracisternal administration of the selective Sig-1R agonist, PRE084, produced TNC neuronal activation as a migraine trigger in rats. A single infusion of PRE084 (10, 50, 100, 500 nmol) significantly increased the number of Fos immunoreactive neurons (Fos-IR) in TNC, which BD1047 (a Sig-1R antagonist) reversed. Chronic infusion of PRE084 (100 nmol for 1, 3, 7 and 14 days) time-dependently elevated Fos-IR in TNC. The number of Fos-IR elevation from day 7 of infusion was comparable with a single capsaicin infusion as a headache model. Increase in face grooming/scratching behavior was evident from day 7, and peaked at day 14 of chronic PRE084 infusion, which was correlated with ΔFosB elevation and phosphorylation of extracellular signal-regulated kinase, and the NMDA receptor NR1 subunit in TNC. Following 14 days of PRE084 infusion, the number of Fos-IR increased until day 7 after final infusion. Moreover, by day 14, Fos-IR associated with PRE084 infusion was significantly reversed by NMDA receptor antagonist MK801, rather than BD1047. These findings indicated that chronic activation of Sig-1R could evoke prolonged neuronal activation in the trigeminovascular system.

Downregulation of ERK signaling impairs U2OS osteosarcoma cell migration in collagen matrix by suppressing MMP9 production.

The present study investigated the role of extracellular signal-regulated kinase (ERK) activation in the migratory phenotype of human U2OS osteosarcoma (OS) cells in a collagen matrix. The activation of ERK was inhibited by PD98059, a specific inhibitor of ERK kinase. Additionally, no significant differences were observed in the adhesion and proliferation of the cells with or without PD98059 treatment in collagen-coated dishes. The migratory capacity of the U2OS cells was then examined in non-coated and collagen-coated dishes, and the results depicted that collagen I enhanced the migration of the U2OS cells, the effect of which was significantly blocked by the treatment of the cells with PD98059. Furthermore, enhanced gene and protein expression of matrix metalloproteinase 9 (MMP9), but not MMP2, was observed to be involved in the enhanced migratory phenotype of the U20S cells in the collagen-coated plates. This effect was partially abolished by the treatment of the cells in the collagen-coated dishes with ERK inhibitor. Collectively, the data demonstrate that ERK signaling is important for the migration of U2OS cells through the extracellular matrix (ECM), which is comprised mostly of collagen, by enhancing MMP9 production. These results may contribute to the regulation of MMP9 production in metastatic OS.

Effect of the position of immobilization upon the tensile properties in injured achilles tendon of rat.

OBJECTIVE: To examine the effect of the posture of immobilization upon the tensile properties in injured Achilles tendon of rat for an initial period of immobilization. METHODS: Forty-two Sprague-Dawley rats were used in the present study. Eighteen rats received a total tenotomy of the right Achilles tendon to mimic total rupture and were divided into three groups comprising of 6 rats each. Ankles of group A were immobilized at 60° of plantarflexion. Ankles of group B were immobilized at neutral position. Whereas, those of group C were immobilized at 60° of dorsiflexion. Other 18 rats received hemitenotomy to mimic partial rupture and were divided into three groups. The remaining 6 rats were kept free as control. After 14 days, we dissected the tendons and analyzed maximum force, stiffness, and energy uptake during pulling of the tendons until they ruptured. The tendons of 6 rats in each group and control were reserved for histology. Picrosirius staining was done for the analysis of collagen organization. RESULTS: In total tenotomy, tensile properties were significantly different between the control and the intervention groups (p<0.05). Group C showed relatively higher values than the groups A and B with respect to tensile properties (p>0.05). In partial tenotomy, tensile properties were significantly different between the control and the intervention groups (p<0.05). Group C showed significantly higher value than other intervention groups in terms of maximum force and energy uptake (p<0.05). The semiquantitative histologic grading scores were assigned for collagen organization. The scores for dorsiflexion posture were higher than the ones for plantarflexion. CONCLUSION: Dorsiflexion posture in partial ruptured Achilles tendon showed better functional recovery than other immobilized postures. In total ruptured case, the tensile properties showed increasing tendency in dorsiflexion posture.

Pain modality and spinal glia expression by streptozotocin induced diabetic peripheral neuropathy in rats.

Pain symptoms are a common complication of diabetic peripheral neuropathy or an inflammatory condition. In the most experiments, only one or two evident pain modalities are observed at diabetic peripheral neuropathy according to experimental conditions. Following diabetic peripheral neuropathy or inflammation, spinal glial activation may be considered as an important mediator in the development of pain. For this reason, the present study was aimed to address the induction of pain modalities and spinal glial expression after streptozotocin injection as compared with that of zymosan inflammation in the rat. Evaluation of pain behavior by either thermal or mechanical stimuli was performed at 3 weeks or 5 hours after either intravenous streptozotocin or zymosan. Degrees of pain were divided into 4 groups: severe, moderate, mild, and non-pain induction. On the mechanical allodynia test, zymosan evoked predominantly a severe type of pain, whereas streptozotocin induced a weak degree of pain (severe+moderate: 57.1%). Although zymosan did not evoke cold allodynia, streptozotocin evoked stronger pain behavior, compared with zymosan (severe+moderate: 50.0%). On the other hand, the high incidence of thermal hyperalgesia (severe+moderate: 90.0%) and mechanical hyperalgesia (severe+moderate: 85.7%) by streptozotocin was observed, as similar to that of zymosan. In the spinal cord, the increase of microglia and astrocyte was evident by streptozotocin, only microglia was activated by zymosan. Therefore, it is recommended that the selection of mechanical and thermal hyperalgesia is suitable for the evaluation of streptozotocin induced diabetic peripheral neuropathy. Moreover, spinal glial activation may be considered an important factor.

Dextromethorphan-induced psychotoxic behaviors cause sexual dysfunction in male mice via stimulation of σ-1 receptors.

Dextromethorphan (DM) is a well-known antitussive dextrorotatory morphinan. We and others have demonstrated that sigma (σ) receptors may be important for DM-mediated neuromodulation. Because an earlier report suggested that DM might affect sexual function and that σ receptor ligands affect signaling pathways in the periphery, we examined whether DM-induced psychotoxic burden affected male reproductive function. We observed that DM had a high affinity at σ-1 receptors in the brain and testis but relatively low affinity at σ-2 receptors. Prolonged treatment with DM resulted in conditioned place preference and hyperlocomotion, followed by an increase in Fos-related antigen expression in the nucleus accumbens in male mice. Simultaneously, DM induced significant reductions in gonadotropin-releasing-hormone immunoreactivity in the hypothalamus. Moreover, we observed that DM induced increased sperm abnormalities and decreased sperm viability and sexual behavior. These phenomena were significantly attenuated by combined treatment with BD1047, a σ-1 receptor antagonist, but not by SM-21, a σ-2 receptor antagonist. Thus, these results suggest that DM psychotoxicity might lead to reproductive stress in male mice by activating σ-1 receptors.

Protective Effect of Ginsenoside Rb1 on Hydrogen Peroxide-induced Oxidative Stress in Rat Articular Chondrocytes.

The abnormal maturation and ossification of articular chondrocytes play a central role in the pathogenesis of osteoarthritis (OA). Inhibiting the enzymatic degradation of the extracellular matrix and maintaining the cellular phenotype are two of the major goals of interest in managing OA. Ginseng is frequently taken orally, as a crude substance, as a traditional medicine in Asian countries. Ginsenoside Rb1, a major component of ginseng that contains an aglycone with a dammarane skeleton, has been reported to exhibit various biological activities, including anti-inflammatory and anti-tumor effects. However, a chondroprotective effect of ginsenoside Rb1 related to OA has not yet been reported. The purpose of this study was to demonstrate the chondroprotective effect of ginsenoside Rb1 on the regulation of pro-inflammatory factors and chondrogenic genes. Cultured rat articular chondrocytes were treated with 100 µM ginsenoside Rb1 and/or 500 µM hydrogen peroxide (H2O2) and assessed for viability, reactive oxygen species production, nitric oxide (NO) release, and chondrogenic gene expression. Ginsenoside Rb1 treatment resulted in reductions in the levels of pro-inflammatory cytokine and NO in H2O2-treated chondrocytes. The expression levels of chondrogenic genes, such as type II collagen and SOX9, were increased in the presence of ginsenoside Rb1, whereas the expression levels of inflammatory genes related to chondrocytes, such as MMP1 and MMP13, were reduced by approximately 50%. These results suggest that ginsenoside Rb1 has potential for use as a therapeutic agent in OA patients.

Anti-apoptotic Activity of Ginsenoside Rb1 in Hydrogen Peroxide-treated Chondrocytes: Stabilization of Mitochondria and the Inhibition of Caspase-3.

Chondrocyte apoptosis has been recognized as an important factor in the pathogenesis of osteoarthritis (OA). Hydrogen peroxide (H2O2), which produces reactive oxygen species, reportedly induces apoptosis in chondrocytes. The ginsenoside Rb1 (GRb1) is the principal component in ginseng and has been shown to have a variety of biological activities, such as anti-arthritis, anti-inflammation, and anti-tumor activities. In this study, we evaluated the effects of G-Rb1 on the mitochondrial permeability transition (MPT) and caspase-3 activity of chondrocyte apoptosis induced by H2O2. Cultured rat articular chondrocytes were exposed to H2O2 with or without G-Rb1 and assessed for viability, MPT, Bcl-xL/Bax expression, caspase-3 activity, and apoptosis. The co-treatment with G-Rb1 showed an inhibition of MPT, caspase-3 activity, and cell death. Additionally, the levels of the apoptotic protein Bax were significantly lower and the levels of the anti-apoptotic protein Bcl-xL were higher compared with H2O2 treatment alone. The results of this study demonstrate that G-Rb1 protects chondrocytes against H2O2-induced apoptosis, at least in part via the inhibition of MPT and caspase-3 activity. These results demonstrate that G-Rb1 is a potentially useful drug for the treatment of OA patients.

Protection by [6]-shogaol against lipopolysaccharide-induced toxicity in murine astrocytes is related to production of brain-derived neurotrophic factor.

[6]-Shogaol has beneficial effects in spinal neuronal regeneration, but associated molecules and mechanisms are not identified. Neurotrophic factors, including brain-derived neurotrophic factor (BDNF), are associated with proliferation and differentiation of neuronal cells and exert a neuroprotective effect in neurodegenerative models. We investigated whether treatment with [6]-shogaol increases BDNF expression in lipopolysaccharide (LPS)-treated astrocytes, and examined the effect of [6]-shogaol on neuronal protection. [6]-Shogaol significantly attenuated the cell death induced by LPS. Western blotting showed that [6]-shogaol treatment reduced Bax expression and increased B-cell lymphoma (Bcl)-2 and BclxL expression in LPS-treated cells, consistent with the effects of BDNF treatment. Furthermore, K252a, a blocker of neurotrophic factors, attenuated the cellular protective effects of [6]-shogaol and BDNF. This study provides the first evidence that [6]-shogaol increases the expression of BDNF in LPS-treated astrocytes. Furthermore, these experimental results indicate that production of BDNF in astrocytes might be related to altered cell viability following [6]-shogaol treatment. Thus, the neuroprotective effects of [6]-shogaol is mediated by up-regulation of BDNF.

Anti-inflammatory effects of [6]-shogaol: potential roles of HDAC inhibition and HSP70 induction.

Ginger extracts have been reported to have anti-inflammatory, anti-oxidant, and anti-cancer effects. [6]-shogaol is one of the most bioactive components of ginger rhizomes. This study assessed the [6]-shogaol's ability to protect cultured primary rat astrocytes against lipopolysaccharide (LPS)-induced inflammation. [6]-shogaol was shown to suppress the release of pro-inflammatory cytokines and decreased the level of inducible nitric oxide syntheses (iNOS), cyclooxygenase-2 (COX-2), and phospho-NF-kB in LPS-treated astrocytes. Furthermore, [6]-shogaol treatment markedly up-regulated histone H3 acetylation and suppressed histone deacetylase (HDAC)1 expression. In addition, [6]-shogaol treatment also increased the expression of heat-shock protein (HSP)70. The neuroprotective, neurotrphic, and anti-inflammatory properties of [6]-shogaol may be translated to improvements in neurological performance. [6]-Shogaol's ability to inhibit HDAC was comparable to that of commonly used HDAC inhibitors Trichostatin A and MS275. Taken together, our results suggest that [6]-shogaol can significantly attenuate a variety of neuroinflammatory responses by inducing HSP70, that is associated with HDAC inhibition in cortical astrocytes.

Effect of bee venom acupuncture on methamphetamine-induced hyperactivity, hyperthermia and Fos expression in mice.

Acupuncture has been used to treat drug addiction by nicotine, alcohol, cocaine and morphine. This study was designed to investigate the effect of bee venom (BV) acupuncture on hyperactivity and hyperthermia induced by acute exposure to methamphetamine (METH, 1mg/kg, s.c.) in mice. Diluted BV (20µl of 0.01, 0.1, 1 and 10mg/ml in saline, s.c.) was administered bilaterally into the Zusanli acupoint (ST36) or control points (SP9 or GB39 or tail base). BV injection into ST36 dose dependently reduced METH-induced hyperactivity and hyperthermia, while BV injection (1mg/ml) into control points did not produce these suppressive effects. METH injection significantly increased Fos expression in several brain regions including nucleus accumbens (NA), caudate putamen (CPU), ventral tegmental area (VTA), substantia nigra (SN) and locus coeruleus (LC). Interestingly, BV (1mg/ml) injection into ST36 further increased METH-induced Fos expression in NA (core and shell), SN and LC. When we performed sciatic denervation or combination treatment of BV and lidocaine (BV diluted in 5% lidocaine solution), the enhancement of Fos elevation by BV was completely blocked in the NA, SN and LC in METH-injected mice, indicating that BV-induced peripheral nerve stimulation played an important role in the BV effect. Furthermore, the effects of BV were completely blocked by the α2-adrenoceptor antagonist, idazoxan (3mg/kg, i.p.), but not by ß-adrenoceptor antagonist, propranolol (10mg/kg, i.p.). Taken together, these findings suggest that BV acupuncture into ST36 may modulate METH-induced hyperactivity, hyperthermia and Fos expression through activation of the peripheral nerve and the central α2-adrenergic activation.

Age-specific effects of 6-hydroxydopamine lesions of the rat medial prefrontal cortex on stress-induced c-fos expression in subcortical areas.

As adolescence is a critical period when dopaminergic neuronal maturation peaks, we hypothesized that 6-hydroxydopamine (OHDA) lesions of the medial prefrontal cortex (mPFC) in adolescent rats would have more negative effects than lesions in adult rats. Therefore, we investigated the effects of 6-OHDA lesions of the mPFC in adolescent and adult rats on stress-induced c-fos expression in the brain. Adolescent and adult Sprague-Dawley rats, aged 4 and 7 weeks on arrival, respectively, were studied. 6-OHDA (8.0 microg) for the lesion groups and ascorbic acid for the sham groups were injected bilaterally into the mPFC. All animals were pretreated with desipramine 30 min before being anesthetized. The control group did not undergo any surgery-related procedure except the desipramine injection. After recovery for 1 week, the rats were subjected to restraint stress for 1 h. Immediately after the stress, the rats were killed and c-fos immunohistochemistry was examined. The c-fos expression in the nucleus accumbens core (AcbC), nucleus accumbens shell (AcbSh), CA1, CA3, dentate gyrus (DG), central amygdaloid (Ce), basolateral amygdaloid (BL), and temporal cortex (Tc) was compared. Adolescent rats with 6-OHDA lesions subjected to restraint stress had greater c-fos expression in the AcbC, AcbSh, DG, Ce, BL, and Tc, compared to the sham and control groups, whereas these differences were not observed among the adult groups. These results suggest that a hypodopaminergic state in the mPFC of adolescent rats, but not adult rats, is related to increased sensitivity to stress, suggesting that damage to or maldevelopment of dopaminergic neurons during adolescence has an age-specific effect. Further research is warranted to investigate the mechanism of the age-specific effect of 6-OHDA lesions of the mPFC.

Sigma-1 Receptor Antagonist BD1047 Reduces Allodynia and Spinal ERK Phosphorylation Following Chronic Compression of Dorsal Root Ganglion in Rats.

Many therapeutic roles have been proposed for sigma-1 receptor (Sig-1R), but the involvement of Sig-1R in neuropathic pain has currently not been well explored. The present study aimed to evaluate the anti-nociceptive effect of Sig-1R antagonist (BD1047) in a rat model of chronic compression of the dorsal root ganglion (CCD), which is a model of human foraminal stenosis and radicular pain. When stainless steel rods were inserted into the intervertebral foramen of lumbar vertebrae 4 and 5, the CCD developed reliable mechanical (from 3 day) and cold allodynia (from 1 day) as compared with the sham operation group. The spinal expressions of Sig-1R and phosphorylation of extracellular signal-regulated kinase (pERK) were significantly increased from day 3 to day 14 after CCD surgery, as is consistent with the manifestation of allodynia. The BD 1047 (10, 30, 100 mg/kg) administered on postoperative days 0~5 dose-dependently suppressed both the induction of allodynia and the elevation of the spinal pERK expression in a manner comparable with that of gabapentin (100 mg/kg). At 7 days post-CCD surgery, BD1047 (10, 30, 100 mg/kg) administration also produced anti-nociceptive effects on the mechanical and cold allodynia similar with those of gabapentin (100 mg/kg). Therefore, this data suggested that Sig-1R may play an important role in both the development and maintenance of CCD-induced neuropathy.

Bee venom suppresses methamphetamine-induced conditioned place preference in mice.

OBJECTIVES: Although acupuncture is most commonly used for its analgesic effect, it has also been used to treat various drug addictions including cocaine and morphine in humans. This study was designed to investigate the effect of bee venom injection on methamphetamine-induced addictive behaviors including conditioned place preference and hyperlocomotion in mice. METHODS: Methamphetamine (1 mg/kg) was subcutaneously treated on days 1, 3 and 5 and the acquisition of addictive behaviors was assessed on day 7. After confirming extinction of addictive behaviors on day 17, addictive behaviors reinstated by priming dose of methamphetamine (0.1 mg/kg) was evaluated on day 18. Bee venom (20 microl of 1 mg/ml in saline) was injected to the acupuncture point ST36 on days 1, 3 and 5. RESULTS: Repeated bee venom injections completely blocked development of methamphetamine-induced acquisition and subsequent reinstatement. Single bee venom acupuncture 30 minutes before acquisition and reinstatement test completely inhibited methamphetamine-induced acquisition and reinstatement. Repeated bee venom acupunctures from day 8 to day 12 after methamphetamine-induced acquisition partially but significantly suppressed reinstatement. DISCUSSION: These findings suggest that bee venom acupuncture has a preventive and therapeutic effect on methamphetamine-induced addiction.