Antinociceptive effect of N-acetyl glucosamine in a rat model of neuropathic pain.

OBJECTIVE: This study was aimed at evaluating the efficacy of glucosamine and potential mechanisms of actions in a neuropathic pain model in rats. METHODS: Glucosamine (500, 1000 and 2000 mg/kg) was administered via gavage route, 1 day before the chronic constriction injury (CCI) of sciatic nerve and daily for 14 days (prophylactic regimen), or from days 5 to 14 post-injury (therapeutic regimen), as the indicators of neuropathic pain, mechanical allodynia, cold allodynia and thermal hyperalgesia were assessed on days 0, 3, 5, 7, 10 and 14 after ligation. Inducible nitric oxide synthase (iNOS) and tumour necrosis factor alpha (TNF-α) gene expressions were measured by real-time polymerase chain reaction. TNF-α protein content was measured using the enzyme-linked immunosorbent assay method. RESULTS: Three days after nerve injury, the threshold of pain was declined among animals subjected to neuropathic pain. Mechanical and cold allodynia, as well as thermal hyperalgesia were attenuated by glucosamine (500, 1000, 2000 mg/kg) in the prophylactic regimen. However, existing pain was not decreased by this drug. Increased mRNA expression of iNOS and TNF-α was significantly reduced in the spinal cord of CCI animals by glucosamine (500, 1000, 2000 mg/kg) in the prophylactic regimen. The overall expression of spinal TNF-α was increased by CCI, but this increase was reduced in animals receiving glucosamine prophylactic treatment. CONCLUSION: Findings suggest that glucosamine as a safe supplement may be a useful candidate in preventing neuropathic pain following nerve injury. Antioxidant and anti-inflammatory effects may be at least in part responsible for the antinociceptive effects of this drug.

Clavulanic Acid Attenuating Effect on the Diabetic Neuropathic Pain in Rats.

Diabetic neuropathy is one of the most common complications of diabetes mellitus. Excess glutamate release and oxidative stress are hypothesized to be involved in the pathophysiology of diabetes-induced neuropathy. This study was designed to investigate the effect of clavulanic acid (CLAV), a competitive beta-lactamase inhibitor, on the streptozocin (STZ)-induced neuropathic pain and possible mechanisms in the spinal cord of rats. Male Wistar rats were divided into naive group; control group which got a single dose of STZ (50 mg/kg, i.p.), as a model of diabetic neuropathic pain; prophylactic groups: animals received CLAV (10, 20 and 40 mg/kg, i.p.) 1 week after STZ for 10 days; and therapeutic group: animals received 20 mg/kg CLAV, 21 days after STZ for 10 days. Study of pain behaviors was started on days 0, 7, 14, 21, 28, 35 and 42 after STZ. The expression of the glutamate transport 1 (GLT1), genes of oxidative stress including inducible nitric oxide synthase (iNOS), proinflammatory cytokine, tumor necrosis factor alpha (TNF-α), as well as genes involved in the apoptosis including bcl2, bcl2-associated x (bax) were measured in the spinal cord tissue by Real Time PCR, on day 42. On day 21 post injection of STZ, diabetic animals showed significant mechanical allodynia, cold allodynia and thermal hyperalgesia. CLAV in all doses of 10, 20 and 40 mg/kg reduced symptoms of allodynia and hyperalgesia, in both prophylactic and therapeutic regimens. While iNOS, TNF-α, bax/bcl2 were found significantly overexpressed in spinal cord of diabetic animals, their expression in animals received CLAV had been reduced. In contrast, GLT1 that had decreased in the spinal cord of diabetic animals, significantly increased in those received CLAV. CLAV was found a promising candidate for reliving neuropathic pain in diabetes mellitus. Such beneficial effect of CLAV could be, in part, attributed to the increased expression of GLT 1, inhibition of nitrosative stress, anti-inflammation, and inhibition of some apoptotic mediators followed by administration into diabetic animals.

An investigation of the anti-inflammatory effects of gabapentin on acetic acid-induced colitis in rats.

Inflammatory bowel disease (IBD) is considered a chronic inflammatory gastrointestinal disease with treatment options which exhibit low efficacies and lead to considerable side effects. Hence, the challenge to alleviate IBD complications is remained to be resolved. The purpose of this study is evaluating anti-inflammatory impacts of gabapentin on acetic acid-induced colitis in rats. Colitis was induced by the instillation of 2 mL of 3% acetic acid solution into rat's colons. Rats were randomly allocated into six groups including normal group, colitis control group, gabapentin-treated groups (25, 50, and 100 mg/kg; i.p.), and dexamethasone-treated group (1 mg/kg; i.p.). Based on the macroscopic assessment besides histological and biochemical findings [myeloperoxidase (MPO), pro-inflammatory cytokines], the efficacy of gabapentin was investigated. Gabapentin (50 and 100 mg/kg), and dexamethasone considerably reduced macroscopic and microscopic colonic lesions induced by acetic acid in rats in comparison with colitis control group. These results were confirmed by reduced levels of MPO activity and colonic concentrations of interleukin-6, interleukin-1 beta, and tumor necrosis factor-alpha, in inflamed colon tissue. Our data demonstrated that gabapentin exerts profitable impacts in experimental colitis that might be ascribed to its anti-inflammatory features and thus can be a potential therapeutic agent for IBD treatment.

Effects of glucosamine against morphine-induced antinociceptive tolerance and dependence in mice.

BACKGROUND: The most important limitations of morphine in pain therapy are its tolerance and dependence. In this study, we evaluated the protective effect of glucosamine against morphine-induced tolerance and dependence in mice. METHODS: Mice received twice daily morphine (20 mg/kg, s.c.) alone, or along with orally administered glucosamine (500, 1000 and 2000 mg/kg), for 9 continuous days. To assess antinociceptive effect of morphine, percentage of maximal possible effect (%MPE) of animals exposed to thermal stimulus was measured in the hot plate test, 30 min after morphine administration. Test was performed on days 1, 3, 5, 7 and 9. The effect of glucosamine on the naloxone (5 mg/kg, i.p.)-precipitated morphine withdrawal, was also evaluated. Changes in brain gene expression levels of induced nitric oxide synthase (iNOS), enzyme responsible for nitric oxide generation, as well as pro-inflammatory mediator, tumor necrosis alpha (TNF-α) were measured in morphine tolerated animals, as well as after withdrawal by real-time polymerase chain reaction (RT-PCR). Protein content of TNF-α was evaluated via ELISA assay. RESULTS: Tolerance to antinociceptive effect of morphine was developed after 7 days of morphine treatment. The concurrent administration of glucosamine (500, 1000 and 2000 mg/kg) with morphine, significantly inhibited tolerance development, on days 7 and 9. In addition, glucosamine ameliorated the naloxone-precipitated opioid withdrawal symptoms (tremor, jumping, teeth chattering, grooming). However, diarrhea was significantly improved only with the dose of 500 mg/kg. Increased mRNA expression of iNOS as well as TNF-α mRNA expression and protein, after both morphine tolerance and withdrawal, were considerably reduced by glucosamine (1000 mg/kg) in the morphine withdrawal animals. CONCLUSION: These data support the utility of glucosamine in attenuating both tolerance to nociceptive effects of morphine as well as withdrawal-induced behavioral profile. Anti-oxidant and anti-inflammatory effects are responsible, at least in part, for the protective effects of this drug.

Neuroprotective effects of clavulanic acid following permanent bilateral common carotid artery occlusion in rats.

We investigated whether clavulanic acid could improve learning and memory, in rats underwent bilateral occlusion of common carotid artery (2VO). Seventy male Wistar rats were subjected to 2VO, with a 1-week interval between right and left artery occlusions. After 2VO, animals received clavulanic acid (10, 20, 40 mg/kg, intraperitoneally), from day 8 to 20. Spatial memory was assessed in the Morris water maze, 1 week after the induction of 2VO (day 15). The mRNA expression levels of bcl-2, bcl2-associated x protein (bax), caspase-3, inducible nitric oxide synthase (iNOS), and amyloid beta precursor protein (APP) were measured in the neocortex and hippocampus. Clavulanic acid significantly decreased the escape latency and swimming time in the training trial days. As well, it increased time and distance percentage in the target quadrant, while it decreased such factors in the opposite quadrant in the final trial day, compared to 2VO + normal saline animals. Real time-PCR data showed a significant higher mRNA expression of bax, caspase 3, and iNOS in the hippocampus and neocortex of 2VO animal compared to nonoccluded rats. APP increased in the neocortex but not hippocampus. Compared with 2VO animals, clavulanic acid significantly down-regulated the expression of iNOS, caspase 3, and APP, accompanied by diminishing the bax/bcl2 ratio. Our results reveal a potential therapeutic use of clavulanic acid for cognitive dysfunction associated with cerebral hypoperfusion in vascular dementia and Alzheimer disease.

Effect of ethanolic extract of Stachys pilifera Benth on subacute experimental models of inflammation and some underlying mechanisms.

BACKGROUND AND PURPOSE: This study was designed to evaluate the anti-inflammatory activities of S. pilifera (HESP) in two sub-acute models of inflammation and clarified some possible mechanisms. EXPERIMENTAL APPROACH: Colorimetric methods were used to determine total phenol and flavonoid contents. Carrageenan or formalin-induced rat paw edema (seven days) and multiple application TPA-induced ear edema in mice (9 days) were used. The concentration of IL-1 and TNF-α were measured in the inflamed paw, as well as MDA levels in the serum and liver. Histopathological studies and in vitro anti-inflammatory effects of the extract were also studied using heat-or hypotonicity-induced hemolysis in RBC humans. FINDINGS/RESULTS: Total phenol and flavonoid contents of HESP were 101.35 ± 2.96 mg GAE/g extract and 660.79 ± 10.06 mg RE g extract, respectively. Oral (100 and 200 mg/kg) and topical application (5 mg/ear) of HESP significantly inhibited formalin-induced paw edema and multiple TPA-induced ear edema. The extract also significantly decreased the serum and liver levels of MDA in the carrageenan and formalin tests. The elevated levels of TNF-α and IL-1ß in the carrageenan-injected paw were not affected by HESP. The extract (50-800 µg/mL) inhibited heat-or hypotonicity-induced hemolysis. Histopathological examination of the inflamed tissues revealed that HESP inhibited congestion and leukocyte infiltration. CONCLUSION AND IMPLICATIONS: The findings confirmed the potent anti-inflammatory effects of S. pilifera in two sub-acute inflammation models and suggested that these properties were not related to IL-1 and TNF-α, but could be attributed to inhibition of lipid peroxidation, membrane stabilization, and inhibition of leukocyte penetration.

Clavulanic acid improves ethanol withdrawal symptoms in rats.

OBJECTIVES: Ethanol withdrawal following chronic use, is an important challenge clinically. In this study, the effect of clavulanic acid was evaluated on the symptoms of ethanol withdrawal in rats. MATERIALS AND METHODS: Alcohol dependence was induced by the gavage of ethanol (10% v/v, 2 g/kg), twice daily for 10 days. Clavulanic acid (10, 20, 40, and 80 mg/kg) was administered concurrently with ethanol (sub-acute study), or a single dose after ethanol withdrawal (acute study). Six hours after the last dose of ethanol, anxiety was assessed by the elevated plus-maze (EPM). Seizure-like behavior was evaluated by a sub-convulsive dose of pentylenetetrazol (PTZ, 25 mg/kg/IP). Locomotor activity and motor coordination were measured by the open field and rotarod tests, respectively. Lipid peroxidation marker and antioxidant content were assessed through measuring malondialdehyde (MDA) and glutathione (GSH), respectively. RESULTS: The number of entries and time spent on the open arms of EPM decreased during the withdrawal state. Motor coordination and locomotor activity were significantly decreased. In the sub-acute study, clavulanic acid 80 mg/kg increased time spent and the number of entries to the open arms of EPM, in withdrawn animals. Both motor incoordination and locomotor activity reduction were normalized by clavulanic acid (10, 20, 40 and 80 mg/kg). Withdrawal-induced PTZ kindling seizure was also suppressed by all of the doses. MDA increased, while GSH decreased after withdrawal. Clavulanic acid attenuated such changes. CONCLUSION: Clavulanic acid could prevent the development of alcohol withdrawal-induced anxiety and seizure. Alcohol withdrawal causes oxidative stress which can be prevented by clavulanic acid.

Predicting the Correlation of EZH2 and Cancer Stem Cell Markers in Esophageal Squamous Cell Carcinoma.

BACKGROUND: Enhancer of zeste homolog 2 (EZH2), a stemness factor, plays roles in regulation of cell differentiation and embryonic development as well as cancer progression. Deregulation of EZH2 in cancers is correlated with tumor cell invasiveness, metastasis, and the patients' poor outcome. However, the mechanistic role of EZH2 in cancer is ambiguous. In this study, we aimed to inhibit the expression of EZH2 in a cancer cell line, and evaluate consequence changes in gene expression pattern. MATERIALS AND METHODS: Using specific retroviral shRNA-EZH2, EZH2 gene was silenced in the KYSE30 cell line. Relative comparative real-time PCR was used to confirm silencing of EZH2 and evaluate expression pattern of selected markers. RESULTS: Inhibition of EZH2 expression in KYSE30 cells caused significant changes in different genes. Indeed, HIWI and HEY1 genes were over- and underexpressed in KYSE30 cells, respectively, following EZH2 silencing. Other selected cancer stem cell markers were not changed significantly. CONCLUSION: To the best our knowledge, there are variety of small molecule inhibitors to target EZH2 in cancer cells as a treatment candidate; therefore, our data in this study helps the researchers to select EZH2 for cancer therapy based on its mechanism and correlation with other markers.