Weight reduction effect of Puerh tea in male patients with metabolic syndrome.

Puerh tea has been proposed to promote weight loss and favorably modify glucose, insulin and blood lipids. This study tested the effect of daily Puerh tea consumption for 3 months on weight and body mass index (BMI), and select metabolic parameters. The effect of daily Puerh tea intake on weight, BMI and changes in glucose, HbA1c and lipids was evaluated in patients with metabolic syndrome. The patients (N = 70) were randomized into two groups: those taking Puerh tea extract capsule (333 mg Puerh tea extract) three times a day and those taking a placebo tea for 3 months. There was a decrease in body weight of 1.3 kg in the Puerh tea group (p = 0.077) versus 0.23 kg in the placebo arm (p = 0.186). There was also a slight decrease in BMI 0.47 kg/m(2) in the Puerh tea group (p = 0.076) versus 0.09 kg/m(2) in the placebo arm (p = 0.185), suggesting a trend of weight change, but without statistical significance. Subgroup analysis of the male patients demonstrated statistically significant improvements in body weight reduction (p = 0.004) and BMI (p = 0.004). However, the change in other metabolic parameters (cholesterol or triglyceride) or HbA1c was not statistically significant. Intake of Puerh tea for 3 months was associated with a slight reduction in body weight and BMI, especially in the male patients. Therefore, daily Puerh tea consumption may be an alternative choice to modify body weight.

Novel regimens of phytopolyphenols and celecoxib enhancing efficacy and selectivity of anticancer effects of chemotherapeutic agents on cultured cancer cells.

Background/purpose: Explorations of novel regimens enhancing efficacy and selectivity of chemotherapeutic agents are urgent to solve the problems of cancer therapy. This study aimed to explore synergistic anticancer effects of novel regimens of phytopolyphenols [curcumin (C), tea polyphenols (G) or GC] with celecoxib (Cl) and ZnSO4. Materials and methods: Antiproliferative effects of drugs on cultured cancer cells and pathogenic biofilms were assayed by MTT and optical density (OD600) respectively; their inhibition on efflux pump (Na+-K+-ATPase) was measured by colorimetric methods. Synergistic (CI < 1) anticancer effects were evaluated by the equations of combination index (CI) and efficacy index (EI). Results: Both Cl and methotrexate (MTX) alone exhibited inhibitory effects not only on proliferation and efflux pump of cultured cancer cells but also pathogenic biofilm formation. Phytopolyphenols (P) and MTX potentiated these inhibitory effects of Cl. In addition, novel regimens containing Cl, memantine (Mem) or thioridazine (TRZ) further enhanced not only efficacy and selectivity of anticancer effects but also inhibition on efflux pump and pathogenic biofilm formation of four chemotherapeutic agents (MTX, cisplatin, 5-fluorouracil and doxorubicin) respectively. Conclusion: In this study, novel regimens of phytopolyphenols (P), targeting drugs (T; Cl, Mem or TRZ) and metal ions (M; ZnSO4) so called PTM regimens exerted not only by themselves but also markedly potentiated efficacy and selectivity of anticancer effects of four chemotherapeutic agents. Because of their potent inhibitions on efflux pump and pathogenic biofilm formation, these combinatorial novel regimens were expected to be able to overcome the problems of multidrug resistant cancers and merit for further clinical studies.

Synergistic antibacterial effects of 5-fluorouracil or thioridazine in combination with phytopolyphenols on cultured Porphyromonas gingivalis.

Background/purpose: 5-Fluorouracil (5FU) is a commonly used anticancer drug. However, the severe oral mucositis induced by 5FU in about 60-70% of patients was a major cause of discontinuous therapy. Since oral dysbiosis induced by 5FU was well correlated with severity of oral mucositis and Porphyromonas gingivalis (P.g.) was a keystone pathogen of dysbiosis. Thus, in this study, we aimed to explore the novel regimens of 5FU combined with phytopolyphenols (curcumin, green tea polyphenols) as well as ZnSO4 on antibacterial effects of cultured P.g. growth. In addition, similar regimens containing thioridazine (TRZ) were also tested for their antibacterial efficacy. Materials and methods: The synergistic (Combination Index (CI) < 1) antiproliferation and anti-protease efficacies (IC50) of novel regimens on cultured P.g. were evaluated by OD600 and colorimetric method respectively. Results: The results obtained indicated that both novel regimens of 5FU and TRZ exhibited potent synergistic antibacterial effects against growth and protease of P.g. Conclusion: These novel regimens of 5-FU and TRZ were potent antibacterial agents which merit for further preclinical and clinical trials in management of oral mucositis, cancers and infectious diseases.

Exposure to low dose of cinnabar (a naturally occurring mercuric sulfide (HgS)) caused neurotoxicological effects in offspring mice.

Cinnabar, a naturally occurring mercuric sulfide (HgS), has long been used in Chinese mineral medicine for more than 2000 years. Although mercury is well-known for its toxicity, whether cinnabar induces neurotoxicity, especially in infants and children, is unknown. The purpose of this study was to explore the neurotoxic effects of low-dose of cinnabar (10 mg/kg/day) on developing mice. The results revealed neurobehavioral defects in F1-C-Cin group, which were associated with Hg accumulation, increased NO(x) levels in whole blood, and Na(+)/K(+)-ATPase activities in brain tissues. F1- and F2-Cin-V groups were found to increase brain Hg contents and prominent neurobehavioral defects compared with F1-C-V group, suggesting that the fetal brain was more susceptible to irreversible effects for cinnabar-induced damage. Moreover, F1- and F2-Cin-Cin groups had severely neurobehavioral dysfunctions, closely correlated with the further alteration of NO(x) levels and Na(+)/K(+)-ATPase activities than F1- and F2-C-Cin groups. Effects in F2-Cin-Cin group were more significant than those in F1-Cin-Cin group. In conclusion, this study demonstrates that exposure to low-dose of cinnabar during the perinatal and developmental stages results in irreversible and severe injuries of the neurotoxicity in offspring, and NO(x) and Na(+)/K(+)-ATPase activities may exist potential and useful biomarkers for neurotoxicity-induced by low-doses of mercuric compounds.

Novel regimens of phytopolyphenols with cisplatin or memantine and ZnSO4 for synergistic inhibition of growth and gingipains of the cultured Porphyromonas gingivalis.

Background/purpose: Porphyromonas gingivalis (P.g.) played a keystone pathogen not only in initiation and progression of periodontitis but also as a risk factor involved in systemic diseases (Alzheimer's disease, cancers, diabetes, osteoporosis etc.). Developments of effective and safe drugs to inhibit P.g. growth are urgent. In this study, we aimed at approaching novel regimens so called (PTM) by combination of repurposing drugs including phytopolyphenols (P) (curcumin, tea polyphenols), targeting drugs (T) such as cisplatin or memantine and metal ions(M) (ZnSO4). Materials and methods: The synergistic (combination Index (CI) < 1) antiproliferation and anti-protease efficacies (IC50) of novel regimens on cultured P.g. were evaluated by OD600 and colorimetric method respectively. Results: The results obtained revealed that these novel regimens (PTM) synergistically (combination index, CI < 1) exerted not only antiproliferative but also anti-gingipain protease effects of P.g. The concentrations for 50% inhibition (IC50) of novel regimens on P.g. growth and gingipains were greatly decreased as compared with those of cisplatin and memantine alone. Conclusion: Since these novel regimens exerted potent anti-bacterial effects on both planktonic and biofilm P.g., it is encouraged for further preclinical and clinical trials.

Clinical implications of oxidative stress in schizophrenia: Acute relapse and chronic stable phase.

Several studies have suggested a higher oxidative stress in schizophrenia. However, the implications of oxidative stress on clinical symptoms remain unclear. This study aimed to investigate the platelet oxidative stress in different stages of schizophrenia (i.e., chronic stable and acute relapse) in order to clarify the clinical implications of oxidative stress and the treatment effects. We recruited 43 chronic stable patients with schizophrenia and 48 non-psychiatric controls. Platelets were collected for measuring the levels of nitric oxide (NO), lipid peroxidation (LPO), and glutathione (GSH) and the activity of GSH peroxidase (GPx) and superoxide dismutase (SOD). The levels and activity were compared between patients and controls and were examined for their relationship with clinical severity. Further, we evaluated the changes of levels and activity before and after treatment in an independent sample with acute relapse (N = 19). Patients with chronic stable schizophrenia had lower SOD activity compared to non-psychiatric controls. In chronic stable patients, NO level was positively correlated with positive and disorganized symptoms, while the GPx activity were negatively correlated with excitement. In patients with acute relapse, the levels and activity were not different before and after four weeks of antipsychotic treatment, but LPO level was negatively correlated with pretreatment disorganized symptoms. The change of LPO can also predict the change of disorganized symptoms and negative symptoms. Our findings suggest that platelet SOD was lower in chronic stable schizophrenia. Platelet LPO may be associated with less disorganized symptoms in acute relapse patients and better treatment response.

Enhancing effects of morphine on methamphetamine-induced reinforcing behavior and its association with dopamine release and metabolism in mice.

Polydrug abuse has become a significant problem worldwide, and the combined use of methamphetamine (MA) and morphine (M) is now highly prevalent among addicts. In the present study, we investigated the neurobehavioral effects of repeated treatment regimens of these drugs (i.p. administration of 0.75 mg/kg/day MA, 5 mg/kg/day M, and their combination for five consecutive days followed by once weekly for five consecutive weeks) in mice. In addition, we used an in vivo microdialysis technique to study the changes in extracellular concentrations of dopamine (DA) and its metabolites in the mouse striatum after challenge administration of these drugs. The results showed that systemic M increased MA-induced conditioned place preference (CPP), as revealed by higher CPP values which were also maintained for a longer duration compared with those induced by an identical dose of MA or M alone. Subsequent to challenge with combined MA and M, mice exhibited an increase in stereotyped behavior, which appeared to be associated with an elevation of extracellular concentration of DA in the striatum. Our findings suggest that M not only produces synergistic effects on MA-induced CPP, but also interacts with MA to induce stereotyped behavioral sensitization which is mediated by an increase in DA outflow in the striatum. These findings provide insight into the behavioral and neurochemical basis responsible for the combined abuse liability of MA and M.

Ursolic acid inhibits IL-1beta or TNF-alpha-induced C6 glioma invasion through suppressing the association ZIP/p62 with PKC-zeta and downregulating the MMP-9 expression.

Ursolic acid (UA), a constant constituent of Rosmarinus officinalis extracts, is a triterpenoid compound which has been shown to have antioxidant and anticarcinogenic properties. In the present study, we found that UA was able to reduce interleukin-1 beta (IL-1beta) or tumor necrosis-alpha (TNF-alpha)-induced rat C6 glioma cell invasion, which was examined by a reconstituted basement membrane in a set of transwell chambers. However, the inhibitory effect of UA did not influence cell proliferation or cause cell cytotoxity. The results analyzed by zymography assay and Western blotting revealed that the activity and expression of matrix metalloproteinase-9 (MMP-9) was eliminated by UA in a dose-dependent manner. Because MMP-9 is the target gene of the transcription factor nuclear factor-kappaB (NF-kappaB), we further investigated the effect of UA on the activity of NF-kappaB. As expected, UA upregulated the levels of IkappaBalpha (IkappaBalpha) and attenuated the nuclear translocation of p65. Furthermore, UA suppressed the IL-1beta or TNF-alpha-induced activation of protein kinase C-zeta (PKC-zeta). Our data showed UA potently inhibited the association of ZIP/p62 and PKC-zeta. Taken together, we demonstrated that UA could efficiently inhibit the interaction of ZIP/p62 and PKC-zeta. It also further suppressed the activation of NF-kappaB and downregulation of the MMP-9 protein, which in turn contributed to its inhibitory effects on IL-1beta or TNF-alpha-induced C6 glioma cell invasion. These results all showcase the potential UA has in the chemoprevention and treatment of cancer metastasis and invasion.

Novel regimen through combination of memantine and tea polyphenol for neuroprotection against brain excitotoxicity.

NMDA receptors are abundant, ubiquitously distributed throughout the brain, fundamental to excitatory neurotransmission, and critical for normal CNS function. However, excessive glutamate overstimulates NMDA receptors, leading to increased intracellular calcium and excitotoxicity. Mitochondrial dysfunction associated with loss of Ca(2+)homeostasis and enhanced cellular oxidative stress has long been recognized to play a major role in cell damage associated with excitotoxicity. In this experiment, we attempted to explore whether treatment with memantine (an NMDA receptor antagonist) and tea polyphenol (an antioxidant and anti-inflammatory agent), either alone or in combination, is effective in neuroprotection in a mouse excitotoxic injury model. Memantine (10 mg/kg/day), tea polyphenol (60 mg/kg/day), or a combination (memantine 5 mg/kg/day plus tea polyphenol 30 mg/kg/day) was administered by oral gavage for 2 consecutive days before causing excitotoxic injury. Mice received a 0.3-microL NMDA [335 mM (pH 7.2)] injection into the left striatum. Locomotor activity was assessed 24 hr before and after excitotoxic injury. Brain synaptosomes were harvested 24 hr after excitotoxic injury for assessment of Na(+), K(+)-ATPase and Mg(2+)-ATPase activity, reactive oxygen species production, mitochondrial membrane potential (Delta Psi m), mitochondrial reductase activity (MTT test), and Ca(2+)concentration. The results showed that treatment with memantine could significantly rescue mitochondrial function by attenuating the decreased mitochondrial membrane potential (Delta Psi m) and mitochondrial reductase activity in mouse excitotoxic injury. Treatment with tea polyphenol could significantly decrease the increased production of synaptosomal reactive oxygen species (ROS) and thus reduced the deteriorative ROS-sensitive Na(+), K(+)-ATPase and Mg(2+)-ATPase activity. However, neither memantine nor tea polyphenol alone could significantly improve the impaired locomotor activity unless treatment was combined. Combined treatment with memantine and tea polyphenol could significantly protect mice against excitotoxic injury by reducing the increased synaptosomal ROS production, attenuating the decreased Na(+), K(+)-ATPase and Mg(2+)-ATPase activity, the mitochondrial membrane potential (Delta Psi m), the mitochondrial reductase activity, and the increased synaptosomal Ca(2+)concentration. In addition, the impairment in locomotor activity was also significantly improved. Therefore, the combined treatment of memantine and tea polyphenol is more effective in neuroprotection than either memantine or tea polyphenol alone in mouse excitotoxic injury. These findings provide useful information about the potential application of memantine and tea polyphenols in preventing clinical excitotoxic injury such as brain trauma, brain ischemia, epilepsy, and Alzheimer's disease.

Methamphetamine-elicited alterations of dopamine- and serotonin-metabolite levels within mu-opioid receptor knockout mice: a microdialysis study.

mu-Opioid receptors (mu-ORs) modulate methamphetamine (MA)-induced behavioral responses, increased locomotor activity and stereotyped behavior in the mouse model. We investigated the changes in dopamine (DA) and serotonin (5-HT) metabolism in the striatum following either acute or repeated MA treatment using in vivo microdialysis. We also studied the role of mu-ORs in the modulation of MA-induced DA and 5-HT metabolism within mu-OR knockout mice. Subsequent to either acute or repeated intraperitoneal administration of MA, wild-type mice revealed decreases in extracellular concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in a dose-dependent manner. Moreover, wild-type mice had reductions in basal concentrations of DOPAC and HVA following repeated MA treatment with a higher dose. The effects of acute, repeated or challenge MA administration upon extracellular levels of DOPAC and HVA within mu-OR knockout mice significantly differed from the wild-type controls. The duration of recovery to the basal levels of extracellular DA and 5-HT metabolites induced by MA were much longer in wild-type mice than for mu-OR knockout mice. These findings suggest that mu-ORs play a modulatory role in MA-induced DA and 5-HT metabolism in the mouse striatum. This possible mechanism of MA-induced behavioral change as modulated by mu-OR merits further study.

Apoptosis of cultured astrocytes induced by the copper and neocuproine complex through oxidative stress and JNK activation.

Astrocytes play a critical neurotrophic and neuroprotective role in the brain, and improper function of these cells may contribute to the onset of neurodegenerative diseases. Because astrocytes are known to be enriched with Cu chaperone proteins, it is important to understand the factors that may lead to cytotoxic effects of Cu on astrocytes. In this report, we demonstrated a dramatic potentiating effect of neocuproine (NCP), a membrane permeable metal chelator, on Cu, but not Fe or Pb, in inducing apoptosis of cultured astrocytes. It was estimated that individually, CuCl2 and NCP only weakly exhibited cytotoxic effects on astrocytes, with EC50 of 180 and 600 microM, respectively. However, NCP at a nontoxic concentration of 10 microM markedly reduced EC50 of Cu to 0.35 microM (physiological concentration) and Cu (10 microM) reduced EC50 of NCP down to 0.06 microM. The mechanisms underlying these dramatic potentiation effects are elucidated. NCP increased the intracellular concentration of Cu in astrocytes and a nonpermeable Cu chelator, bathocuproine disulfonate was able to abolish all of the apoptotic signaling. Cell death was determined to be via apoptosis due to increased reactive oxygen species production, mitochondrial dysfunction, depletion of glutathione and adenosine triphosphate, cytochrome c release, c-Jun N-terminal kinase, and caspase-3 activation, and poly-ADP-ribose polymerase degradation. This finding, coupled with our previous reports, suggests that metal chelators (NCP, dithiocarbamate and disulfiram) should be cautiously used as they may potentiate a cytotoxic effect of endogenous Cu on astrocytes. Their clinical implications in the etiology of neurodegenerative diseases deserve further investigation.

Effects of methylprednisolone on nitric oxide formation and survival of facial motor neurons after axotomy.

The aims of this study were to evaluate the effect of a high dose (160 mg/kg) of methylprednisolone sodium succinate (MPSS) on the formation of endogenous nitric oxide (NO) in the brainstem after facial nerve transection and to explore whether this effect has relevance to the survival of facial motor neurons. Guinea pig facial nerves were transected at the tympanic segment, and half were administered with MPSS, while the other half were given a vehicle of saline solution. Post operation NO formation in the brainstem at different time points was directly measured with a NO/ozone chemiluminescence technique. The surviving motor neurons were counted in histological coronal frozen sections of facial motor nuclei. The present results revealed that facial nerve transection induced a significant increase in NO formation in the brainstem by 1 week in both MPSS and saline treated groups and lasted to the end of the study (4 weeks). Compared to the saline treated group, it appeared that MPSS administration could delay the increase of nitric oxide synthase (NOS) expression and NO formation during the first 1 approximately 2 weeks after facial nerve transection. The survival rate of facial motor neurons was significantly higher in the MPSS treated group than in the saline treated group when examined at 3 or 4 weeks after facial nerve transection. These results indicate that a high dose of MPSS elicited a delayed increase of NO formation and thus may concomitantly enhance the survival time of motor neurons after facial nerve transection.

Involvement of activating transcription factors JNK, NF-kappaB, and AP-1 in apoptosis induced by pyrrolidine dithiocarbamate/Cu complex.

Pyrrolidine dithiocarbamate (PDTC) is a metal chelator. Biologically, slight toxic affects EC50, 100+/-5.9 microM are observed when added to cultured HL-60 cells. CuCl2 at a physiological concentration (1 microM), but not FeCl2, Pb potentiated the cytotoxic effect of PDTC by 700 fold (EC50, 0.14+/-0.02 microM). Furthermore, results indicated that the PDTC/Cu complex induced an apoptotic process, evidenced by apoptotic bodies, DNA ladder and hypodiploidy cells. Additional studies showed that PDTC/Cu complex significantly decreased mitochondrial membrane potential, increased cytochrome c release, and reactive oxygen species production, and depleted reduced non-protein thiols in a time-dependent manner. Following oxidative stress, the PDTC/Cu complex sequentially activated JNK, NF-kappaB and AP-1 signaling pathways while IkappaB kinase activity was enhanced. The apoptotic process was eventually induced by caspase 3 activation and PARP degradation. The non-permeable copper-specific chelator-bathocuproine disulfonate (BCPS) and vitamin C were able to inhibit apoptosis and the elevation of intracellular Cu. Based on these findings; we conclude that PDTC/Cu complex-induced apoptosis is mediated by activation of JNK, NF-kappaB, AP-1 and caspase 3. Due to its high potency, PDTC may be useful as a therapeutic anti-cancer drug.

Ototoxicity induced by cinnabar (a naturally occurring HgS) in mice through oxidative stress and down-regulated Na(+)/K(+)-ATPase activities.

Cinnabar, a naturally occurring mercuric sulfide (HgS), has long been used in Chinese mineral medicine for more than 2000 years; currently it is still used as a sedative for infants in Asian countries. Since methylmercury is potently ototoxic, whether cinnabar also induces hearing impairment is awaited for delineation. In this study, we attempted to explore the toxic effects of cinnabar on the auditory brainstem response (ABR) system during 2-10 weeks administration at a clinical oral dosage of 10mg/kg/day in mice. The results showed that Hg contents of the brainstem were significantly increased accompanied with gradually progressive abnormality of ABR during 4-10 weeks of cinnabar administration. The progressive increase in hearing thresholds, prolonged absolute and interwave latencies of ABR apparently exhibited a gender difference. Male mice were more sensitive to cinnabar in producing hearing impairment correlated with the biochemical alterations in plasma and brainstem, e.g. an increase of lipid peroxidation (LPO), altered Na(+)/K(+)-ATPase activities and decrease of nitric oxide (NO(x)) levels. Moreover, accumulation of Hg contents in brainstem with a greater extent was found in male mice. These findings provide important information that the clinical dosage of cinnabar (10mg/kg/day) still exhibited ototoxicity after continuously long-term exposure. The signaling pathway of oxidative stress/Na(+)-K(+)-ATPase activities/NO of brainstem (a central auditory regulatory system) probably plays an important role in the toxic mechanisms of cinnabar-induced ototoxicity. The gender difference in cinnabar-induced neurotoxic effects merits further investigation.

Neurotoxicological mechanism of methylmercury induced by low-dose and long-term exposure in mice: oxidative stress and down-regulated Na+/K(+)-ATPase involved.

Methylmercury (MeHg), a potent neurotoxicant, easily passes through the blood-brain barrier (BBB), accumulates in the brain regions and causes severe irreversible damage. However, the neurotoxic effects and action mechanisms of MeHg are still unclear, especially in low-dose and long-term exposure. In this study, we attempted to explore the toxic effects of low-dose MeHg (0.05 mg/kg/day), which was the possible exposed dose by ingestion in MeHg-contaminated areas, on the time course of changes in locomotor activities and auditory brainstem response (ABR) system after administration for 7 consecutive weeks in mice. The results showed that the retention time on the rotating rod (60 rpm) was preferentially decreased after 1-week oral administration with MeHg. The locomotor activities parameters of ambulatory distances and stereotype-1 episodes were significantly increased and vertical-plane entries were progressively decreased after MeHg exposure in 3 consecutive weeks. Gradually progressive abnormality of ABR (increase in hearing thresholds, prolonged absolute and interwave latencies) was found during 4-6 weeks administration of MeHg. These impairments correlated with significant Hg accumulation and biochemical alterations in brain regions and/or other tissues, including the increase of lipid peroxidation (LPO) production, influence of Na+/K(+)-ATPase activities and nitric oxide (NO) levels were found. These findings provide evidence that the signaling of oxidative stress/Na+/K(+)-ATPase/NO plays a role in the underlying mechanisms of the neurotoxic effects induced by low-dose and long-term exposure of MeHg.

Chronologic changes of nitric oxide concentration in the cochlear lateral wall and its role in noise-induced permanent threshold shift.

OBJECTIVE: The objective of this study was to investigate the chronologic changes of nitric oxide (NO) concentration in the cochlear lateral wall and to explore its possible role in permanent threshold shift (PTS) after intense noise exposure. MATERIALS AND METHODS: Seventeen guinea pigs were subjected to a single continuous exposure to broadband white noise at 105 +/- 2 dB sound pressure level (SPL) for 40 hours and were divided into four groups according to various postnoise recovery periods. Another 12 guinea pigs were not exposed to noise and served as controls. The hearing status of all animals was evaluated with auditory brainstem responses (ABR) evoked by condensation "click" sounds. ABR were recorded both prior to noise exposure and immediately before killing the animal. After death, NO concentration in the cochlear lateral wall was directly measured with an NO/ozone chemiluminescence technique. RESULTS: An approximately 1.7-fold increase in NO concentration was observed immediately postnoise exposure, which persisted for up to 28 days. The threshold of ABR elevation (mean, 30 dB SPL) peaked immediately after cessation of noise exposure and gradually resolved to a PTS (mean, 14.5 dB SPL) 56 days after noise exposure when NO concentration had returned to its prenoise exposure level. CONCLUSION: Noise-induced threshold shift, which resolved to a mild PTS, can be partially attributed to NO elevation in the cochlear lateral wall. Our results revealed a nonlinear correlation between ABR recovery and depletion of NO, indicating that the mechanisms of NO changes in the cochlear lateral wall may be more complicated than previously conceived and that other pathophysiologic mechanisms may also play important roles in noise-induced PTS.

Studies on a novel regimen for management of orofacial pain and morphine tolerance.

BACKGROUND/PURPOSE: The prevalence of orofacial pain is high but the etiology of orofacial pain is not well understood. Because of clinical treatment is not so effective, it is urgent to explore novel regimens with more effective and less side effects for clinical application. MATERIALS AND METHODS: Male mice (ICR strain) were injected with capsaicin (10µg/5 µl) in vibrissa pad. Spontaneous orofacial pain in 20 min was recorded after receiving capsaicin to quantify the nociceptive level. Green tea polyphenols (GTP 60 mg/kg), memantine (Mem 10 mg/kg), and GTPm (GTP 30 mg/kg plus Mem 3 mg/kg) were dissolved in 2% carboxymethyl cellulose, which was orally administered to mice twice per day and five times per week consecutively for 2 weeks. TruScan photobeam tracking was used to record changes of behavior and locomotor activities. RESULTS: GTPm by itself attenuated orofacial pain induced by capsaicin. Moreover, GTPm enhanced morphine analgesic effects, reduced morphine depressant side effects and delayed morphine tolerance. Along with this experiment, GTPm was tested on the hot plate (52 °C)-induced peripheral thermal pain. It was found that both memantine and GTPm reduced morphine-analgesia in hind paw thermal pain. CONCLUSION: In this study, GTP (60 mg/kg/day) orally administrated produced a significant analgesic effect on capsaicin-induced orofacial pain. Memantine combined with GTP synergistically not only reduced orofacial pain but also enhanced morphine analgesic effects. Thus, a new regimen of GTPm orally administered twice per day attenuated orofacial pain after consecutive 5 days.

The role of phosphoinositide 3-kinase/Akt signaling in low-dose mercury-induced mouse pancreatic beta-cell dysfunction in vitro and in vivo.

The relationship between oxidation stress and phosphoinositide 3-kinase (PI3K) signaling in pancreatic beta-cell dysfunction remains unclear. Mercury is a well-known toxic metal that induces oxidative stress. Submicromolar-concentration HgCl(2) or methylmercury triggered reactive oxygen species (ROS) production and decreased insulin secretion in beta-cell-derived HIT-T15 cells and isolated mouse islets. Mercury increased PI3K activity and its downstream effector Akt phosphorylation. Antioxidant N-acetyl-l-cysteine (NAC) prevented mercury-induced insulin secretion inhibition and Akt phosphorylation but not increased PI3K activity. Inhibition of PI3K/Akt activity with PI3K inhibitor or by expressing the dominant-negative p85 or Akt prevented mercury-induced insulin secretion inhibition but not ROS production. These results indicate that both PI3K and ROS independently regulated Akt signaling-related, mercury-induced insulin secretion inhibition. We next observed that 2- or 4-week oral exposure to low-dose mercury to mice significantly caused the decrease in plasma insulin and displayed the elevation of blood glucose and plasma lipid peroxidation and glucose intolerance. Akt phosphorylation was shown in islets isolated from mercury-exposed mice. NAC effectively antagonized mercury-induced responses. Mercury-induced in vivo effects and increased blood mercury were reversed after mercury exposure was terminated. These results demonstrate that low-dose mercury-induced oxidative stress and PI3K activation cause Akt signaling-related pancreatic beta-cell dysfunction.

Differential neurotoxic effects of methylmercury and mercuric sulfide in rats.

Methylmercury (MeHg) is an environmental toxicant, while mercuric sulfide (HgS) is a main active component of cinnabar, a Chinese mineral medicine used as a sedative. Because the neurotoxicological effects of HgS were not clearly understood, in this study, we attempted to compare HgS with MeHg in various physiological responses in Sprague-Dawley rats. After oral administration (2 mg/(kg day)) for consecutive 5 and 14 days, MeHg reversibly decreased both of motor nerve conduction velocity (MNCV) and tail flick response, whereas irreversibly inhibited all of the motor equilibrium performance, recovery of compound muscle action potentials (CMAP) following exhaustic tetanic stimuli and Na+/K+-ATPase activity of the isolated sciatic nerve. These toxic effects of MeHg were found in well correlation of Hg contents of various tissues (blood, cerebral cortex, liver and kidney) in rats. For comparison, a dose of 1g/(kg day) of HgS was orally administered to the rats based on our previous findings on ototoxicity of HgS. The results revealed that HgS only reversibly delayed the recovery of suppressed CMAP and inhibited sciatic nerve Na+/K+-ATPase activity in accordance to the lower Hg contents of the tissues. These findings provide the important information on the differential susceptibility of various nervous tissues to MeHg and HgS. The neruotoxic effects produced by HgS was estimated to be about 1000 of those induced by MeHg found in this study and our previous reports.

The diabetogenic effects of the combination of humic acid and arsenic: in vitro and in vivo studies.

Black foot disease (BFD) is a peripheral arterial occlusive disease found among the inhabitants of the southwest coast of Taiwan. Moreover, within the BFD-endemic areas, diabetes mellitus occur at significantly higher rates than in other areas of Taiwan. A high concentration of humic acid (HA), and arsenic (As) are present in the artesian well water from BFD-endemic area. The aim of this paper is to study the diabetogenic effect of the combination of HA and AS. Treatment of HIT-T15 cells with HA, As, or both of them resulted loss of cell viability, apoptosis, depletion of ATP, increment of oxidative stress, activation of caspase 3, and dysfunction of insulin secretion. In addition, the plasma insulin of ICR mice, which were exposed to HA and As in drinking water for 12 weeks, was decreased in the 5, 7, and 12 weeks, and increased at early stage of exposure (3 weeks). The results reported herein reveal that HA and As exert HIT-T15 cell dysfunction and inhibited insulin secretive effects. In addition, the sub-acute peri-pancreatitis and islet damage caused by the infiltration of inflammatory cells after exposure of HA and As in drinking water for 5 weeks. Our study has important implications in the diabetogenic effect of the HA and AS which may be mediated by ROS and further information of the toxicity mechanisms will provide under our progressive studies.