Protective Effects of Glatiramer Acetate Against Paclitaxel-Induced Peripheral Neuropathy in Rats: A Role for Inflammatory Cytokines and Oxidative Stress.

Chemotherapy-induced peripheral neuropathy (CIPN) is a major challenge for cancer patients who undergo chemotherapy with paclitaxel. Therefore, finding effective therapies for CIPN is crucial. Glatiramer acetate is used to treat multiple sclerosis that exerts neuroprotective properties in various studies. We hypothesized that glatiramer acetate could also improve the paclitaxel-induced peripheral neuropathy. We used a rat model of paclitaxel (2 mg/kg/every other day for 7 doses)-induced peripheral neuropathy. Rats were treated with either different doses of glatiramer acetate (1, 2, 4 mg/kg/day) or its vehicle for 14 days in separate groups. The mechanical and thermal sensitivity of the rats by using the Von Frey test and the Hot Plate test, respectively, were assessed during the study. The levels of oxidative stress (malondialdehyde and superoxide dismutase), inflammatory markers (TNF-α, IL-10, NF-kB), and nerve damage (H&E and S100B staining) in the sciatic nerves of the rats were also measured at the end of study. Glatiramer acetate (2 and 4 mg/kg) exerted beneficial effects on thermal and mechanical allodynia tests. It also modulated the inflammatory response by reducing TNF-α and NF-κB levels, enhancing IL-10 production, and improving the oxidative stress status by lowering malondialdehyde and increasing superoxide dismutase activity in the sciatic nerve of the rats. Furthermore, glatiramer acetate enhanced nerve conduction velocity in all treatment groups. Histological analysis revealed that glatiramer acetate (2 and 4 mg/kg) prevented paclitaxel-induced damage to the nerve structure. These results suggest that glatiramer acetate can alleviate the peripheral neuropathy induced by paclitaxel.

Effect of Metformin on Epidermal Neural Crest Stem Cells and Their Potential Application in Ameliorating Paclitaxel-induced Neurotoxicity Phenotype.

AIMS: Epidermal Neural Crest Stem Cells (EPI-NCSCs) have emerged as prospective ideal candidates to meet the fundamental requirements of cell-based therapies in neurodegenerative disorders. The present study aimed to identify the potential of metformin in driving EPI-NCSCs to neuronal/glial differentiation and express neurotrophic factors as well as assess their therapeutic potential for mitigating the main behavioral manifestations of chemotherapy-induced neurotoxicity (CIN). MAIN METHODS: EPI-NCSCs were extracted from the bulge region of hair follicle. Following expansion, transcript and protein expression profiles of key markers for stemness (Nestin, EGR-1, SOX-2 and 10), neurotrophic activity (BDNF, GDNF, NGF, FGF-2, and IL-6), and neuronal (TUB3, DCX, NRF and NeuN) and glial (PDGFRα, NG2, GFAP, and MBP) differentiation were determined on days 1 and 7 post-treatment with 10 and 100 µM metformin using real time-PCR and immunocytochemistry methods. Then, the in vivo function of metformin-treated stem cells was evaluated in the context of paclitaxel CIN. To do so, thermal hyperalgesia, mechanical allodynia, and spatial learning and memory tests were evaluated by Hotplate, Von Frey, and Morris water maze tests. KEY FINDINGS: Our result indicated that exposure of EPI-NCSCs to metformin was associated with progressive decline in stemness markers and enhanced expression levels of several neurotrophic, neuron and oligodendrocyte-specific markers. Further, it was observed that intranasal metformin-treated EPI-NCSCs improved the cognitive impairment, and mechanical and thermal hypersensitivity induced by paclitaxel in rats. SIGNIFICANCE: Collectively, we reasoned that metformin pretreatment of EPI-NCSCs might further enhance their therapeutic benefits against CIN.

4-Methylimidazole, a carcinogenic component in food, amount, methods used for measurement; a systematic review.

4-methylimidazole (4-MEI) is widely used industrially. This carcinogenic component has been reported in some types of food. It is usually produced by the caramelization process in food, drinks and caramel coloring. The possible mechanism for the formation of this compound in food is the Maillard reaction. In order to estimate the amount of substance 4-MEI in food, a systematic study was conducted. The selected keywords were 4-methylimidazole, 4-MEI, beverage, drink, meat, milk, and coffee. 144 articles were obtained from the initial search. The articles were evaluated and finally, the data of 15 manuscripts were extracted. Based on the data extracted from selected articles, the highest amount is reported in caramel color, coffee, and cola drinks. In 70% of the selected studies, the analytical method was based on liquid chromatography. In this method, there is no need for derivatization. SPE columns were used to extract samples in most manuscripts. According to per capita consumption, the most exposure to 4-MEI is through coffee. In high risk food products, regular monitoring with analytical methods with high sensitivity is recommended. Furthermore, most of the selected studies were about the validation method, so few samples were selected. It is recommended to design more studies with a high sample size to accurately evaluate this carcinogenic compound in food.

Gastroprotective effect of sumatriptan against indomethacin-, stress- and ethanol-induced gastric damage in male rats: Possible modulatory role of 5-hydroxytryptamine 1B/1D receptors and pro-inflammatory cytokines.

The current study was aimed to investigate the beneficial effect of sumatriptan, a 5-hydroxytryptamine 1B/1D (5HT1B/1D ) receptor agonist, on gastric ulcer in rats via stimulating 5HT1B/1D receptors and suppressing pro-inflammatory cytokines. Rats were allocated into three models of gastric ulcer: indomethacin (30 mg/kg, PO), water immersion restraint stress (WRS) and ethanol (5 ml/kg PO). Animals were administered with sumatriptan (0.01, 0.1, 0.3 and 1 mg/kg, i.p) 30 min before gastric ulcer induction. GR-127935 (0.01 mg/kg, i.p, a selective 5HT1B/1D antagonist) was administered 30 min before sumatriptan (0.1 mg/kg) injection. Macroscopic assessments (J-score), ELISA analysis of tumour necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1ß) and histopathological changes were performed on the rat's stomach tissues. Gastric ulcer induction in three models caused an increase in J-score, TNF-α, IL-1ß and microscopic features. Sumatriptan (0.1 mg/kg) significantly improved gastric injury induced by indomethacin, WRS and ethanol through the reduction in the J-score, TNF-α, IL-1ß and microscopic lesions. Concurrent administration of GR-127935 (0.01 mg/kg) with sumatriptan (0.1 mg/kg) reversed the gastroprotective effect of sumatriptan in three models. Sumatriptan possessed gastroprotective effects on indomethacin-, WRS- and ethanol-induced gastric damage in rats via the possible involvement of the 5HT1B/1D receptors.

In vivo Analgesic Activity of New N-arylphthalimides Derivatives in Mice.

BACKGROUND: A series of phthalimides related to thalidomide have been studied for analgesic activity in the formalin test. The formalin test was performed in mice in a nociceptive pattern to evaluate analgesic activity. METHODS: In this study, nine derivatives of phthalimides were evaluated in terms of exerting analgesic effects in mice. They exerted significant analgesic effects compared to indomethacin and negative control. These compounds were synthesized and characterized by TLC, followed by IR and H1NMR in the previous studies. Two distinct periods of high licking activity were used to analyze both acute and chronic pain. All compounds were compared with indomethacin and carbamazepine as positive control and vehicle as a negative control. RESULTS: All of the tested compounds exhibited significant analgesic activity in both the first and second phases of the test compared to the control group (DMSO), although they did not show more activity than the reference drug (indomethacin) but were comparable to indomethacin. CONCLUSION: This information may be useful in the development of a more potent phthalimide as an analgesic agent that acts as a sodium channel blocker and COX inhibitor.

Anticonvulsant effects of ivermectin on pentylenetetrazole- and maximal electroshock-induced seizures in mice: the role of GABAergic system and KATP channels.

Introduction: Ivermectin (IVM) is an antiparasitic medicine that exerts its function through glutamate-gated chloride channels and GABAA receptors predominantly. There is paucity of information on anti-seizure activity of IVM. Moreover, the probable pharmacological mechanisms underlying this phenomenon have not been identified. Materials and methods: In this study, pentylenetetrazole (PTZ)-induced clonic seizures and maximal electroshock (MES)-induced tonic-clonic seizure models, respectively in mice was utilized to inquire whether IVM could alter clonic seizure threshold (CST) and seizure susceptibility. To assess the underlying mechanism behind the anti-seizure activity of IVM, we used positive and negative allosteric modulators of GABAA (diazepam and flumazenil, respectively) as well as KATP channel opener and closer (cromakalim and glibenclamide, respectively). Data are provided as mean ± S.E.M. After the performance of the variance homogeneity test, a one-way and two-way analysis of variance was used. Fisher's exact test was performed in case of MES. P-value less than 0.05 considered statistically significant. Results: and Discussion: Our data showed that IVM (0.5, 1, 5, and 10 mg/kg, i.p.) increased CST. Furthermore, flumazenil 0.25 mg/kg, i.p. and glibenclamide 1 mg/kg, i.p., could inhibit the anticonvulsant effects of IVM. Supplementary, an ineffective dose of diazepam 0.02 mg/kg, i.p. or cromakalim 10 µg/kg, i.p. were able to enhance the anticonvulsant effects of IVM. Besides, we figure out that the IVM (1 and 5 mg/kg, i.p.) could delay the onset of first clonic seizure and also might decrease the frequency of clonic seizures induced by PTZ (85 mg/kg, i.p.). Finally, IVM could prevent the incidence and death in MES-induced tonic-clonic seizures. Conclusion: Based on the obtained results, it can be concluded that IVM may exert anticonvulsant effects against PTZ- and MES-induced seizures in mice that might be mediated by GABAA receptors and KATP channels.

Opioidergic and nitrergic systems mediate the anticonvulsant effect of mefloquine and chloroquine on seizures induced by pentylenetetrazol and maximal electroshock in mice.

This study was designed to investigate the involvement of opioidergic/nitrergic systems in the anticonvulsant effect of mefloquine, compared with chloroquine, in mice. Seizures were induced by pentylenetetrazol and maximal electroshock. Mice were randomly subjected to receive mefloquine or chloroquine thirty minutes in advance. The role of opioidergic/nitrergic systems was shown by co­administration of pharmacological intervention and nitrite levels measurement in mice hippocampi. Results indicated that mefloquine (40 mg/kg) and chloroquine (5 mg/kg) significantly decreased the occurrence of tonic hindlimb extension. Also, mefloquine 120 mg/kg and chloroquine 5 mg/kg significantly increased seizure latency and decreased mortality rate. Mefloquine decreased seizure frequency too. Besides, mefloquine (20 mg/kg) and chloroquine (5, 10 mg/kg) significantly increased seizure threshold. Interestingly, L­NAME, 7­NI and naltrexone pre­treatment reversed the anticonvulsant effects of both mefloquine (20 mg/kg) and chloroquine (5 mg/kg). Moreover, co­administration of minimal­effective doses of morphine with mefloquine/chloroquine (both 1 mg/kg) potentiated anticonvulsant effects, which was reversed by naltrexone and endorsed the involvement of opioid receptors. Also, nitrite levels in mice hippocampi remarkably increased after treatment with both mefloquine (20 mg/kg) and chloroquine (5 mg/kg). To conclude, mefloquine could protect the central nervous system against seizures in PTZ/MES­induced models through opioidergic/nitrergic pathways, with similarity to chloroquine effects.

The N-methyl-D-aspartate receptor antagonist ketamin exerts analgesic effects via modulation of the nitric oxide pathway.

Ketamine, an NMDA receptor antagonist, has been approved to have analgesic effects. It is known that nitric oxide pathway is involved in antinociception but with dual effects. In this study, we investigated the role of nitric oxide in ketamine-induced analgesia. Ketamine was administered to mice acute and chronically with/without nitric oxide synthase (NOS) inhibitors. Experimental models of nociception pain, including hot plate, tail flick, and formalin tests, were performed. Western blot was used to measure levels of nitric oxide synthase enzymes in the brain. Ketamine doses of 0.03 and 0.3 mg/kg had significant analgesic effects (p < 0.01). High-dose chronic ketamine could induce analgesia in later phases of the treatment in tail flick test (p < 0.01). Pretreatment with various NOS inhibitors decreased the analgesic effect. In western blot analysis, the expression of NOS proteins was decreased. Low-dose ketamine is effective in analgesia induction. The expression of nNOS and iNOS proteins is dependent on the inhibition of the NMDA/NO pathway.

Montelukast suppresses the development of irritable bowel syndrome phenotype possibly through modulating NF-κB signaling in an experimental model.

Irritable bowel syndrome (IBS) is a functional gut disorder with multi-factorial pathophysiology that causes recurring pain or discomfort in the abdomen, as well as altered bowel habits. Montelukast, a well-known cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, is widely used for the anti-inflammatory management of asthma. The present study aimed to evaluate the effects of pharmacological inhibition of CysLT1R on acetic acid-induced diarrhea-predominant IBS (D-IBS) in rats. Behavioral pain responses to noxious mechanical stimulation were decreased in the montelukast-treated rats as compared to the model animals following colorectal distension (CRD)-induced visceral hypersensitivity. Stool frequency decreased dose-dependently by montelukast in IBS rats exposed to restraint stress. A significantly shorter immobility time was also observed in IBS rats who received montelukast vs IBS group in the forced swimming test (depression-like behavior). Furthermore, there were significant decreases in the NF-κB protein expression, inflammatory cytokine (TNF-α, and IL-1ß) levels, and histopathological inflammatory injuries concomitant with increased anti-inflammatory cytokine, IL-10, in montelukast-treated rats compared with the IBS group. Cysteinyl leukotriene production and CysLT1R mRNA expression showed no remarkable differences among the experimental groups. The present results suggest the possible beneficial effects of montelukast in the management of D-IBS symptoms. The molecular mechanism underlying such effects, at least to some extent, might be through modulating CysLT1R-mediated NF-κB signaling. Yet, more studies are required to demonstrate the clinical potential of this drug for IBS therapy.

Left Ventricular Strain Rate for Intraoperative Evaluation of Cardiac Diastolic Function by Transesophageal Echocardiography: The Correlation Between Late Diastolic Peak Longitudinal Strain Rate and the Severity of Diastolic Dysfunction.

OBJECTIVES: Speckle-tracking echocardiography is a promising tool for evaluating cardiac diastolic dysfunction. A correlation between left atrial strain rate during atrial contraction and the severity of diastolic dysfunction previously has been demonstrated. Because visualization of the left atrial walls is difficult with transesophageal echocardiography, the authors evaluated the use of left ventricular strain rate during atrial contraction as a substitute for left atrial strain rate to intraoperatively measure the extent of cardiac diastolic dysfunction. DESIGN: Retrospective clinical study. SETTING: Single institutional study. PARTICIPANTS: Sixty-six patients who underwent cardiac surgery between January 2018 and January 2021. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Preoperative echocardiographic reports and intraoperative echocardiographic images of the participants were studied. The correlation of cardiac diastolic dysfunction stage with the peak longitudinal strain rate during late diastole and the time to peak value were evaluated. The late diastolic peak longitudinal strain rate was correlated significantly with the stage of diastolic dysfunction (r = -0.64, p < 0.0001). There was no significant correlation between the stage of diastolic dysfunction and the time to peak value (r = -0.17, p = 0.18). A late diastolic peak longitudinal strain rate <0.68 1/s had a sensitivity of 80% and specificity of 81% for predicting grade 2 or 3 diastolic dysfunction. CONCLUSIONS: The late diastolic peak longitudinal strain rate correlates with the severity of diastolic dysfunction in patients undergoing cardiac surgery.

The protective effect of α7-nACh receptor and its interaction with 5-HT1B/1D receptors in acute intestinal ischemia-reperfusion injury in rats.

Over the past decades, great attention has been given to the nervous system modulating effects on the immune response in inflammation-associated injuries, such as acute intestinal ischemia-reperfusion (IR). Recently, we proved the anti-inflammatory and antioxidant effects of 5-hydroxytryptamine (5-HT)1B/1D receptors in intestinal IR injury in rats. Also, the alpha7 nicotinic acetylcholine (α7-nACh) receptor has anti-inflammatory effects in different inflammation-associated injuries. Starting from these premises, we aimed to examine the function of the α7-nACh receptors and the functional interactions between the anti-inflammatory and antioxidant effects of α7-nACh and 5-HT1B/1D receptors in acute intestinal IR injury. To confirm the expression and localization of α7-nACh receptors on the ileum nerves, an immunofluorescence-based method was applied. Then, intestinal IR injury was induced by 30-min occlusion of superior mesenteric artery and reperfusion for 2 h in rats. Acute systemic administration of α7-nACh receptor agonist PNU-282987 and antagonist methyllycaconitine, and 5-HT1B/1D receptors agonist (sumatriptan) and antagonist (GR127, 935) were used in the model of intestinal IR injury. Finally, biochemical and histological parameters were assessed. Α7-nACh receptors were expressed by 9% on the ileum nerves. Likewise, activation of the α7-nACh receptor showed anti-inflammatory and antioxidant effects in intestinal IR injury but not as well as 5-HT1B/1D receptors. Interestingly, 5-HT1B/1D receptors via attenuation of glutamate (Glu) release indirectly activated the α7-nACh receptor and its protective effects against inflammation and oxidative stress. The protective effect of the α7-nACh receptor on intestinal IR injury was activated indirectly through the 5-HT1B/1D receptors' modulatory impact on Glu release.

Therapeutic Effects of Azithromycin on Spinal Cord Injury in Male Wistar Rats: A Role for Inflammatory Pathways.

BACKGROUND: Inflammatory responses, including macrophages/microglia imbalance, are associated with spinal cord injury (SCI) complications. Accumulating evidence also suggests an anti-inflammatory property of azithromycin (AZM). MATERIAL AND METHODS: Male Wistar rats were subjected to T9 vertebra laminectomy. SCI was induced by spinal cord compression at this level with an aneurysmal clip for 60 seconds. They were divided into three groups: the sham-operated group and two SCI treatment (normal saline as a vehicle control vs. AZM at 180 mg/kg/d intraperitoneally for 3 days postsurgery; first dose: 30 minutes after surgery) groups. Locomotor scaling and behavioral tests for neuropathic pain were evaluated and compared through a 28-day period. At the end of the study, tissue samples were taken to assess neuroinflammatory changes and neural demyelination using ELISA and histopathologic examinations, respectively. In addition, the proportion of M1/M2 macrophage polarization was assessed by using flow cytometry. RESULTS: Post-SCI AZM treatment (180 mg/kg/d for 3 days) significantly improved locomotion (p < 0.01) and decreased sensitivity to mechanical (p < 0.01) and thermal allodynia (p < 0.001). Moreover, there was a significant tumor necrosis factor-α (TNF-α) decline (p < 0.01) and interleukin-10 (IL-10) elevation (p < 0.01) in the spinal cord tissue of the AZM-treated group compared with the control groups 28 days post-SCI. AZM significantly improved neuroinflammation as evidenced by reduction of the M1 expression, elevation of M2 macrophages, and reduction of the M1/M2 ratio in both the dorsal root ganglion and the spinal cord tissue after SCI compared with controls (p < 0.01). CONCLUSION: AZM treatment can be considered a therapeutic agent for SCI, as it could reduce neuroinflammation and SCI sensory/locomotor complications.

Anti-seizure effects of walnut peptides in mouse models of induced seizure: The involvement of GABA and nitric oxide pathways.

Epilepsy is one of the foremost medical disorders. Oxidative stress is a well-known mechanism in epileptogenesis, and many studies suggest that oxidative stress affects the onset and evolution of epilepsy. Here we evaluated the walnut peptide extracts' anti-seizure property in three different mouse seizure models including pentylenetetrazole-induced clonic seizure, chemical kindling, and maximal electroshock. Walnut peptides (20 mg/Kg) were administered by intraperitoneal (IP) injection of mice 60 min before seizure induction in the three models. To delineate the mechanisms of walnut peptides anti-seizure activity, we evaluated the impact of diazepam, flumazenil, and a NOS inhibitor on this activity. Intraperitoneal administration of walnut peptides significantly increased the seizure threshold. Our results also demonstrated that walnut peptides exert their anti-seizure properties through the modulation of benzodiazepine receptors. Thus, walnut peptides may be considered as a new anti-convulsion agent, which can reduce seizure occurrence and slow down seizure progression.

Glatiramer acetate attenuates depressive/anxiety-like behaviors and cognitive deficits induced by post-weaning social isolation in male mice.

RATIONALE: Major depressive disorder (MDD) is a debilitating disorder with adverse effects on mood, memory, and quality of life. OBJECTIVES: In this study, the antidepressant potential of glatiramer acetate (GA), a drug used in the management of multiple sclerosis, was investigated in acute and chronic models of depression in male mice. The acute antidepressant screening was performed with the forced swim (FST) and tail suspension (TST) tests. In the chronic phase, post-weaning social isolation (SI) was used to induce depressive-/anxiety-like behaviors. METHODS: Mice were reared in two different groups of social (SG) and isolated (IG) for 4 weeks. IG mice were treated with 0.5, 1.0, and 2.0 mg/kg of GA for the last 2 weeks of the SI period. Animals were assessed by the behavioral tests of depression, anxiety, learning, and memory, and hippocampal brain-derived neurotrophic factor (BDNF) level was measured. RESULTS: The acute tests confirmed the antidepressant potential of GA. In the chronic phase, GA could reduce immobility time in FST (P < 0.05), increase exploration activity in open field test (P < 0.05), increase open arms duration (P < 0.05) and entries in elevated plus maze (P<0.001), and improve memory and learning in passive avoidance test (P < 0.05). The BDNF level was increased in IG mice and decreased in IG mice treated with GA. CONCLUSIONS: Our results showed that GA improved depressive-/anxiety-like behaviors and cognitive dysfunction of SI reared mice without increasing the BDNF level which may be associated with other mechanisms of actions of GA.

Glatiramer acetate treatment inhibits inflammatory responses and improves survival in a mice model of cecal ligation and puncture-induced sepsis.

OBJECTIVES: Sepsis is a clinical crisis which has been considered as one of the important causes of mortality across the world. We hypothesized that modulation of hyper-inflammatory phase of sepsis pathophysiology can lead to protective effects on survival outcome. Glatiramer acetate (GA) is a neuroprotective drug commonly used in multiple sclerosis (MS). GA is characterized by immunom activity via regulation of innate and adaptive immunity. This study was designed to evaluate the acute treatment with GA on initial inflammatory response-induced mortality in septic mice. METHODS: Cecal ligation and puncture (CLP) model was operated on male mice as a model of Polymicrobial sepsis. GA was administrated intraperitoneally after the sepsis induction at doses of 0.5, 1, and 2 mg/kg in three treatment groups. To investigate the effect of GA on short-term survival, septic mice were observed during 72 h after CLP. Serum levels of TNF-α, IL-1ß, and IL-6 as pro-inflammatory cytokines and also IL-10 as a critical anti-inflammatory cytokine were analysed. To consider sepsis-induced acute kidney injury, renal functional biomarkers and histopathological changes was assessed. RESULTS: GA treatment significantly improved survival rate at doses of 1, and 2 mg/kg. Survival improvement was accompanied by remarkable reduction in the pro-inflammatory cytokines and enhanced production of IL-10. GA showed to have protective effects on renal function as well. CONCLUSIONS: Immunomodulatory and anti-inflammatory properties of GA resulted in increase in survival rate and decrease in inflammatory markers in mice model of cecal ligation and puncture-induced sepsis.

Antibiotics with therapeutic effects on spinal cord injury: a review.

Accumulating evidence indicates that a considerable number of antibiotics exert anti-inflammatory and neuroprotective effects in different central and peripheral nervous system diseases including spinal cord injury (SCI). Both clinical and preclinical studies on SCI have found therapeutic effects of antibiotics from different families on SCI. These include macrolides, minocycline, ß-lactams, and dapsone, all of which have been found to improve SCI sequels and complications. These antibiotics may target similar signaling pathways such as reducing inflammatory microglial activity, promoting autophagy, inhibiting neuronal apoptosis, and modulating the SCI-related mitochondrial dysfunction. In this review paper, we will discuss the mechanisms underlying therapeutic effects of these antibiotics on SCI, which not only could supply vital information for investigators but also guide clinicians to consider administering these antibiotics as part of a multimodal therapeutic approach for management of SCI and its complications.

5-[Aryloxypyridyl (or nitrophenyl)]-4H-1,2,4-triazoles as novel flexible benzodiazepine analogues: Synthesis, receptor binding affinity and lipophilicity-dependent anti-seizure onset of action.

A new series of 5-(2-aryloxy-4-nitrophenyl)-4H-1,2,4-triazoles and 5-(2-aryloxy-3-pyridyl)-4H-1,2,4-triazoles, possessing C-3 thio or alkylthio substituents, was synthesized and evaluated for their benzodiazepine receptor affinity and anti-seizure activity. These analogues revealed similar to significantly superior affinity to GABAA/benzodiazepine receptor complex (IC50 values of 0.04-4.1 nM), relative to diazepam as the reference drug (IC50 value of 2.4 nM). To determine the onset of anti-seizure activity, the time-dependent effectiveness of i.p. administration of compounds on pentylenetetrazole induced seizure threshold was studied and a very good relationship was observed between the lipophilicity (cLogP) and onset of action of studied analogues (r2 = 0.964). The minimum effective dose of the compounds, determined at the time the analogues showed their highest activity, was demonstrated to be 0.025-0.1 mg/kg, relative to diazepam (0.025 mg/kg).

Lithium reverses the effect of opioids on eNOS/nitric oxide pathway in human umbilical vein endothelial cells.

The main challenge of pain management with opioids is development of acute and chronic analgesic tolerance. Several studies on neuronal cells have focused on the molecular mechanisms involved in tolerance such as cyclic AMP (cAMP) activation, and nitric oxide (NO) pathway. However, the effects of opioids on non-neuronal cells and tolerance development have been poorly investigated. Lithium chloride is a glycogen synthase kinase 3ß (GSK-3ß) inhibitor and exert its effects through modulation of nitric oxide pathway. In this study we examined the effect of lithium on acute/chronic morphine and methadone administration in endothelial cells which express mu opioid receptors. Human umbilical vein endothelial cells (HUVECs) were treated with different doses of morphine, methadone, and lithium for six and 48 h. Then we evaluated cell viability, nitrite and cyclic AMP levels, as well as the expression of endothelial nitric oxide synthase (eNOS) protein using Immunocytochemistry (ICC) assay and phosphorylated GSK-3ß enzyme by western blot analysis in cells. Both chronic morphine and methadone treatment increased NO level and eNOS expression in HUVECs. Morphine induced cAMP overproduction after 48 h exposure with cells. Lithium pretreatment (10 mM) in both morphine and methadone received groups significantly reduced nitrite and cAMP levels as well as eNOS expression as compared to the control. The decreased amount of phospho GSK-3ß due to the opioid exposure was increased following lithium treatment. Tolerance like pattern may occur in non-neuronal cells with opioid receptors and this study clearly revealed the attenuation of morphine and methadone tolerance like behavior by lithium treatment in HUVECs.

Interaction of morphine tolerance with pentylenetetrazole-induced seizure threshold in mice: The role of NMDA-receptor/NO pathway.

N-methyl-d-aspartate receptor (NMDA-R)/nitric oxide (NO) pathway is involved in the intensification of the analgesic effect of opioids and the reduction of the intensity of opioids tolerance and dependence. In the current study, we investigated the involvement of NMDA-R/NO pathway in chronic morphine-treated mice in both the development of tolerance to the analgesic effect of morphine and in pentylenetetrazole (PTZ)-induced seizure threshold. Chronic treatment with morphine (30 mg/kg) exhibited increased seizure resistance in morphine-induced tolerant mice. The development of morphine tolerance was withdrawn when used concomitantly with NOS inhibitors and NMDA-R antagonist, suggesting that the development of tolerance to the anticonvulsant effect of morphine (30 mg/kg) is mediated through the NMDA-R/NO pathway. A dose-dependent biphasic seizure modulation of morphine was demonstrated in the acute treatment with morphine; acute treatment at a dose of 0.5 mg/kg shows the anticonvulsant effect and at a dose of 30 mg/kg shows proconvulsant effect. However, a different pattern was observed in the mice treated chronically with morphine: they demonstrated tolerance in the tail-flick test; five consecutive days of chronic treatment with a high dose of morphine (30 mg/kg) showed anticonvulsant effect while a low dose of morphine (0.5 mg/kg) showed a proconvulsant effect. The anticonvulsant effect of morphine was inhibited completely by the concomitant administration of NO synthase (NOS) inhibitors including nonspecific NOS inhibitor (L-NAME, 10 mg/kg), inducible NOS inhibitor (aminoguanidine, 50 mg/kg), and neuronal NOS inhibitor (7-nitroindazole (7-NI), 15 mg/kg) for five consecutive days. Besides, five days injection of NMDA-R antagonist (MK-801, 0.05 mg/kg) significantly inhibited the anticonvulsant effect of morphine on the PTZ-induced clonic seizures. The results revealed that chronic treatment with morphine leads to the development of tolerance in mice, which in turn may cause an anticonvulsant effect in a high dose of morphine via the NMDA-R/NO pathway.

Aripiprazole prevents from development of vincristine-induced neuropathic nociception by limiting neural NOS overexpression and NF-kB hyperactivation.

PURPOSE: Increased nitric oxide (NO) synthesis and NF-kB activation have been shown as critical players in the pathophysiology of vincristine-induced peripheral neuropathy. Consistently, neural nitric oxide synthase (nNOS) inhibitors alleviated the neuropathic pain. Previous studies demonstrated that aripiprazole is capable of modulating NO synthesis and also has been reported its modulatory effect on NF-kB activity. METHODS: Aripiprazole was administered daily to the male Wistar rats at the same time with establishing neuropathic model by I.P. injection of vincristine every 2 days, over 2 weeks. Efficacy of aripiprazole in suppressing the development of neuropathy was evaluated by assessing changes in body weight, mechanical threshold, withdrawal latency, sciatic nerve conduction velocity (SNCV), and compound motor action potential (CMAP) characteristics. Expression of nNOS and NF-kB activation were evaluated by western blotting RESULTS: Rats receiving aripiprazole during neuropathy establishment period demonstrated a normal weight gain pattern, a significantly higher mechanical withdrawal threshold, and SNCV compared to vincristine-treated group. Furthermore, the amplitude and area of CMAP were significantly higher in aripiprazole group. Western blotting demonstrated a significantly reduced expression of nNOS and NF-kB activation in dorsal root ganglia of aripiprazole co-treated rats. CONCLUSION: In conclusion, aripiprazole effectively prevents from vincristine-induced neuropathy by limiting nNOS overexpression and NF-kB hyperactivation.