Involvement Of Nitric Oxide Pathway Research Articles

Sex differences in the anticompulsive-like effect of memantine: Involvement of nitric oxide pathway but not AMPA receptors

Memantine, an N-Methyl-D-Aspartate (NMDA) antagonist, has been examined as a potential treatment for Obsessive-Compulsive Disorder (OCD). Yet, there is limited knowledge regarding how it works to reduce compulsive behaviour and whether it has different effects on individuals based on their sex. Herein, we investigated if there are sex differences in the anticompulsive-like effect of memantine in adult Swiss mice. Additionally, we explored whether the nitric oxide (NO) pathway and α-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA) receptors play a role in memantine's effects. To start, we assessed the impact of a single intraperitoneal dose of memantine (at 3, 5, and 10 mg/kg) on behaviours exhibited in the open field test (OFT) and the marble-burying test (MBT), the latter being a predictive test for anticompulsive effects. All doses of memantine reduced marble-burying behaviour in both male and female mice without affecting their locomotor activity in the OFT. This anticompulsive-like effect was also confirmed in another predictive test, the nest-building test, with the highest memantine dose (10 mg/kg) reducing nest-building behaviour without significant differences between male and female mice. We observed that pre-treatment with L-arginine, a NO precursor, mitigated the anticompulsive-like effect of memantine in male mice but had no effect in female mice in the MBT. Finally, NBQX, an AMPA receptor antagonist, did not block the anticompulsive-like effect of memantine. In summary, our study suggests that the anticompulsive-like effect of memantine does not appear to be sex-specific, does not depend on AMPA receptors, and involves the NO pathway primarily in male mice.

Protective Effects of Dapsone on Scopolamine-Induced Memory Impairment in Mice: Involvement of Nitric Oxide Pathway

Introduction: The leading cause of memory impairment is dementia-related disorders. Since current treatments for memory impairment target the neuroinflammatory pathways, we selected dapsone, an anti-inflammatory agent, to evaluate its effects on scopolamine-induced memory impairment in mice and the underlying role of nitric oxide (NO). Methods: Scopolamine (1 mg/kg, intraperitoneal [i.p.]) was used for induction of memory impairment. The animals received various doses of dapsone (0.1, 0.3, 1, 5, and 10 mg/kg, i.p.). Duration and number of arms visits in the Y-maze and step-through latency in the passive-avoidance were documented. To evaluate the underlying signaling pathway, N(ω)-nitro-L-arginine methyl ester (a nonspecific NO synthase [NOS] inhibitor), aminoguanidine (a specific inducible NOS inhibitor), and 7-nitroindazole (a specific neuronal NOS inhibitor) were administered 30 min after dapsone administration. Results: Dapsone (5 mg/kg) substantially improved memory acquisition in scopolamine-induced memory impairment. Additionally, NOS inhibitors considerably reversed the observed neuroprotective effects of dapsone, accompanied by the elevation of NO levels. Conclusion: Dapsone revealed a neuroprotective effect against scopolamine-induced memory impairment in mice, possibly through the nitrergic pathway.

Involvement of nitric oxide pathway in the acute anticonvulsant effect of salmon calcitonin in rats

Epilepsy is a chronic neurological disease that is thought to affect up to 1% of the world’s population. Evidence suggests that salmon calcitonin (sCT) has positive effects on epileptic seizures and epileptogenesis. However, it remains unknown that whether nitric oxide (NO) pathway contributed to this antiepileptic effect of sCT. We have used the pentylenetetrazole (PTZ)-induced seizure rat model to identify the effect of sCT on seizure score, seizure-induced cognitive deficit, and the NO pathway in the brain. We found that sCT increases the first myoclonic jerk (FMJ), decreased Racine’s convulsion scale (RCS), and abates seizure-induced cognitive impairment. We further demonstrated that sCT attenuated the abnormal increase of NO in the brain. These results revealed that sCT exerts an antiepileptic effect by modulating the NO pathway in the brain.

Effects of catechin on a rodent model of autism spectrum disorder: implications for the role of nitric oxide in neuroinflammatory pathway.

The present research work aims at deciphering the involvement of nitric oxide pathway and its modulation by ( ±)catechin hydrate in experimental paradigm of autism spectrum disorders (ASD). An intracerebroventricular infusion of 4μl of 1M propanoic acid was given in the anterior region of the lateral ventricle to induce autism-like phenotype in male rats. Oral administration of ( ±)catechin hydrate (25, 50, and 100mg/kg) was initiated from the 3rd day lasting till the 28th day. L-NAME (50mg/kg) and L-arginine (800mg/kg) were also given individually as well as in combination to explore the ability of ( ±)catechin hydrate to act via nitric oxide pathway. Behavior test for sociability, stereotypy, anxiety, depression, and novelty, repetitive, and perseverative behavior was carried out between the 14th and 28th day. On the 29th day, animals were sacrificed, and levels of mitochondrial complexes and oxidative stress parameters were evaluated. We also estimated the levels of neuroinflammatory and apoptotic markers such as TNF-α, IL-6, NF-κB, IFN-γ, HSP-70, and caspase-3. To evaluate the involvement of nitric oxide pathway, the levels of iNOS and homocysteine were estimated. Treatment with ( ±)catechin hydrate significantly ameliorated behavioral, biochemical, neurological, and molecular deficits. Hence, ( ±)catechin hydrate has potential to be used as neurotherapeutic agent in ASD targeting nitric oxide pathway-mediated oxidative and nitrosative stress responsible for behavioral, biochemical, and molecular alterations via modulating nitric oxide pathway. The evaluation of the levels of iNOS and homocysteine conclusively establishes the role of nitric oxide pathway in causing behavioral, biochemical, and molecular deficits and the beneficial effect of ( ±)catechin hydrate in restoring these alterations.

Differentiated PDGFRα-Positive Cells: A Novel In-Vitro Model for Functional Studies of Neuronal Nitric Oxide Synthase

It is evident that depletion of interstitial cells and dysfunction of nitric oxide (NO) pathways are key players in development of several gastrointestinal (GI) motility disorders such as diabetic gastroparesis (DGP). One of the main limitations of DGP research is the lack of isolation methods that are specific to interstitial cells, and therefore conducting functional studies is not feasible. The present study aims (i) to differentiate telomerase transformed mesenchymal stromal cells (iMSCs) into platelet-derived growth factor receptor-α-positive cells (PDGFRα-positive cells) using connective tissue growth factor (CTGF) and L-ascorbic acids; (ii) to investigate the effects of NO donor and inhibitor on the survival rate of differentiated PDGFRα-positive cells; and (iii) to evaluate the impact of increased glucose concentrations, mimicking diabetic hyperglycemia, on the gene expression of neuronal nitric oxide synthase (nNOS). A fibroblastic differentiation-induction medium supplemented with connective tissue growth factor was used to differentiate iMSCs into PDGFRα-positive cells. The medium was changed every day for 21 days to maintain the biological activity of the growth factors. Gene and protein expression, scanning electron and confocal microscopy, and flow cytometry analysis of several markers were conducted to confirm the differentiation process. Methyl tetrazolium cell viability, nitrite measurement assays, and immunostaining were used to investigate the effects of NO on PDGFRα-positive cells. The present study, for the first time, demonstrated the differentiation of iMSCs into PDGFRα-positive cells. The outcomes of the functional studies showed that SNAP (NO donor) increased the survival rate of differentiated PDGFRα-positive cells whereas LNNA (NO inhibitor) attenuated these effects. Further experimentations revealed that hyperglycemia produced a significant increase in expression of nNOS in PDGFRα-positive cells. Differentiation of iMSCs into PDGFRα-positive cells is a novel model to conduct functional studies and to investigate the involvement of NO pathways. This will help in identifying new therapeutic targets for treatment of DGP.

Protective effect of modafinil on skin flap survival in the experimental random-pattern skin flap model in rats: The role of ATP-sensitive potassium channels and nitric oxide pathway

Background The brain-stimulating agent modafinil acts through nitric oxide (NO) and adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, involved in the skin flap survival (SFS). The main aim of this study was to investigate the efficacy of modafinil on SFS in rats through the involvement of NO pathway and KATP channels. Methods Using controlled experiment study design, we enrolled a sample of Wistar male rats. Different doses of modafinil (10, 25, 50, and 100 mg/kg) were injected intraperitoneally (i.p.) before the surgery. L-NAME (non-selective nitric oxide synthase [NOS] inhibitor), aminoguanidine (inducible NOS inhibitor), and 7-nitroindazole (neuronal NOS inhibitor) were administered prior to modafinil. The role of KATP channels was determined by coadministering glibenclamide (KATP channel blocker) or cromakalim (KATP channel opener) with modafinil. The predictor variables were administration of different doses of modafinil, and the coadministration of modafinil with L-NAME, aminoguanidine, 7-nitroindazole, glibenclamide, and cromakalim. The main outcome variables included the percentage of necrotic area (PNA) in flap tissues, histopathological results, vascular endothelial growth factor (VEGF) immunohistochemical (IHC) staining, and nitrite concentrations. Appropriate statistics were computed considering p-value ≤ 0.05 significant. Results Modafinil 25 mg/kg was the most effective dose (PNA: 26 [95% CI: 19–33]) vs. control (PNA: 81 [95% CI: 71–92]) (p< 0.001). All NOS inhibitors significantly reversed the protective effect of modafinil (p< 0.001). Non-effective dose of cromakalim had a synergistic effect with the sub-effective dose of modafinil (10 mg/kg), while glibenclamide reversed the effect of modafinil 25 mg/kg (p< 0.001). Conclusions Modafinil increases SFS mediated by NO pathway and KATP channels, which could therefore be a target to improve SFS. The brain-stimulating agent modafinil acts through nitric oxide (NO) and adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, involved in the skin flap survival (SFS). The main aim of this study was to investigate the efficacy of modafinil on SFS in rats through the involvement of NO pathway and KATP channels. Using controlled experiment study design, we enrolled a sample of Wistar male rats. Different doses of modafinil (10, 25, 50, and 100 mg/kg) were injected intraperitoneally (i.p.) before the surgery. L-NAME (non-selective nitric oxide synthase [NOS] inhibitor), aminoguanidine (inducible NOS inhibitor), and 7-nitroindazole (neuronal NOS inhibitor) were administered prior to modafinil. The role of KATP channels was determined by coadministering glibenclamide (KATP channel blocker) or cromakalim (KATP channel opener) with modafinil. The predictor variables were administration of different doses of modafinil, and the coadministration of modafinil with L-NAME, aminoguanidine, 7-nitroindazole, glibenclamide, and cromakalim. The main outcome variables included the percentage of necrotic area (PNA) in flap tissues, histopathological results, vascular endothelial growth factor (VEGF) immunohistochemical (IHC) staining, and nitrite concentrations. Appropriate statistics were computed considering p-value ≤ 0.05 significant. Modafinil 25 mg/kg was the most effective dose (PNA: 26 [95% CI: 19–33]) vs. control (PNA: 81 [95% CI: 71–92]) (p< 0.001). All NOS inhibitors significantly reversed the protective effect of modafinil (p< 0.001). Non-effective dose of cromakalim had a synergistic effect with the sub-effective dose of modafinil (10 mg/kg), while glibenclamide reversed the effect of modafinil 25 mg/kg (p< 0.001). Modafinil increases SFS mediated by NO pathway and KATP channels, which could therefore be a target to improve SFS.

Involvement of nitric oxide pathway in the anti-inflammatory effect of modafinil on indomethacin-, stress-, and ethanol -induced gastric mucosal injury in rat

Gastric ulcer is a prevalent disease with various etiologies, including non-steroidal anti-inflammatory drugs (NSAIDs), stress conditions, and alcohol, resulting in an inflammatory condition in the gastric mucosa. The aim of this study was to explore the protective effects of modafinil on gastric erosions induced by indomethacin, water-immersion stress, and alcohol in rats and to evaluate the role of nitric oxide (NO) pathway. Animals were allocated to the three experimental models of gastric ulcer – indomethacin (30 mg/kg PO), water-immersion stress, and ethanol (5 ml/kg PO). Induction of gastric ulcer in all models caused an increase in J-score (macroscopic assessment), biochemical markers, including tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and myeloperoxidase (MPO), and microscopic destructions. Administration of modafinil (50 and 100 mg/kg i. p) significantly improved J-score in the indomethacin (P < 0.05) and stress models (P < 0.001). Moreover, the level of TNF-α IL-1β, and MPO was deceased after modafinil administration (P < 0.001). However, modafinil did not have any effects on gastric injury induced by ethanol. In addition, co-administration of L-NAME (a non-specific NO synthase inhibitor) and aminoguanidine (an inducible NO synthase inhibitor) with modafinil significantly neutralized the gastroprotective effect of modafinil in the indomethacin and water-immersion stress groups (P < 0.05, and P < 0.01; respectively), while 7-nitroindazole (a neuronal NO synthase inhibitor) did not show such reversing effects. In conclusion, modafinil possesses gastroprotective effects on the gastric lesions induced by indomethacin and stress, which are probably mediated via the inflammation inhibition and NO pathway modulation.

Antinociceptive effect of Lonchocarpus araripensis lectin: activation of L-arginine/NO/cGMP/K+ATP signaling pathway.

The involvement of nitric oxide pathway in the antinociceptive activity of Lonchocarpus araripensis lectin (LAL) was investigated in the model of carragenan-induced hypernociception. Swiss mice received LAL (0.01-10mg/kg; i.v.) 30min before s.c. injection of carragenan in the paws. For the involvement of nociceptive pathways, animals were previously treated with the blockers: NOS (L-NAME, aminoguanidine, 7-nitroindazole); soluble guanylyl cyclase (ODQ); channels of ATP-dependent K+ (glibenclamide); L-type Ca2+ (nifedipine), or Ca2+-dependent Cl- (niflumic acid). Participation of lectin domain was evaluated by injection of LAL associated with N-acetyl-glucosamine (GlcNAc). nNOS gene relative expression was evaluated in the paw tissues and nNOS immunostaining in dorsal root ganglia. LAL at all doses inhibited carrageenan-induced hypernociception (4.12 ± 0.58g), being maximal at 10mg/kg (3h: 59%), and reversed by GlcNAc. At this time, LAL effect was reversed by nifedipine (39%), niflumic acid (59%), L-NAME (59%), 7-nitroindazole (44%), ODQ (45%), and glibenclamide (34%), but was unaltered by aminoguanidine. LAL increased (95%) nNOS gene expression in mice paw tissues, but not its immunoexpression in the dorsal root ganglia. The antinociceptive effect of Lonchocarpus araripensis lectin involves activation of the L-arginine/NO/GMPc/K+ATP pathway.

Biochemical and histopathological evidence for the beneficial effects of modafinil on the rat model of inflammatory bowel disease: involvement of nitric oxide pathway.

Inflammatory bowel disease is an intestinal disorder presented by recurrent inflammation in the gastrointestinal tract. It has been reported that modafinil, also known as an awakening drug, has anti-inflammatory characteristics. The objective of this experiment is to investigate the protective effects of modafinil on colitis induced by acetic acid in rat and the involvement of nitric oxide pathway. Colitis was induced by intra-rectal instillation of 1ml acetic acid (4%). After one h of colitis induction (first day), intraperitoneal injection of dexamethasone (1mg/kg), modafinil (50, 100, and 150mg/kg), nitric oxide synthase inhibitors (NOS)-N (G)-nitro-L-arginine methyl ester (L-NAME) 10mg/kg, 7-nitroindazole 40mg/kg, and aminoguanidine 50mg/kg-was performed and continued for 2 consecutive days. Ultimately, macroscopic, microscopic, and biochemical assessments were performed. While induction of colitis caused severe macroscopic lesions, administration of dexamethasone and modafinil (100 and 150mg/kg) significantly improved macroscopic ulcers. Interestingly, the combination of modafinil with NOS inhibitors reversed the beneficial effects of modafinil on macroscopic destructions. In addition, the elevated level of interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) was decreased by modafinil. However, treatment with NOS inhibitors before modafinil neutralized the anti-inflammatory influence of modafinil. Additionally, histological disorders emerged by acetic acid in colon tissue remarkably were disappeared after treatment with modafinil. In conclusion, modafinil has a protective effect on injuries induced by acetic acid in the colon of rat, which is presumably via the inhibition of inflammatory cascade and mediation of NO pathway.

Effects of onopordia, a novel isolated compound from Onopordon acanthium, on pentylenetetrazole-induced seizures in mice: Possible involvement of nitric oxide pathway

Epilepsy is identified as a brain disorder and characterized by unpredictable disruption of normal brain function. Due to adverse side effect associated with antiepileptic drugs and also resistance profile, improvement of antiepileptic medications with more beneficial anticonvulsant activity is essential. Natural products have demonstrated their therapeutic properties such as anxiolytic, antidepressant and anticonvulsant activities and a source for identification of novel lead compounds. Therefore, the purpose of this study was to evaluate the effects of Onopordon acanthium secondary metabolite, onopordia, on pentylenetetrazole (PTZ)-induced seizure in male mice and investigate the possible role of nitric oxide pathway. Different doses of onopordia (0.1, 1 and 10 mg/kg) and phenobarbital (20 mg/kg) were administered intraperitoneally (i.p., 30, 60 and 120 min) prior to induction of epileptic seizure and compared to control groups. Onopordia demonstrated anticonvulsant effects when administrated at dose of 10 mg/kg, i.p. and optimum time 60 min prior to induction of seizure. Anticonvulsant effect of onopordia was blocked by applying a single dose of a non-selective nitric oxide synthase (NOS) inhibitor, Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; 10 mg/kg, i.p.), and also a single dose of a selective neuronal NOS (nNOS) inhibitor, 7-nitroindazole (7-NI; 30 mg/kg, i.p.). Administration of ketamine as a N-Methyl-d-aspartic acid (NMDA) receptor antagonist (0.5 mg/kg; i.p.) with onopordia did not change the anticonvulsant effect of onopordia. The results of the present study demonstrated the anticonvulsant effect of onopordia as a new lead compound and also contribution of NO/nNOS pathway on PTZ-induced seizure in mice.

Ascorbic acid eliminated pain-induced peripheral neuropathy by modulation of nitric oxide pathway in rats

Ascorbic acid (AA) diminishes superoxide and thereby prevents peroxynitrite formation from superoxide and nitric oxide (NO). As the neuropathic pain could be a consequence of a defect in antioxidant defenses and changes in reactive nitrogen species, the present study was designed to investigate the involvement of NO pathway in the analgesic effect of ascorbate in the chronic constriction injury (CCI) of the sciatic nerve model in rats. Neuropathic pain induced by CCI of sciatic nerve. Sixty-four adult male rats were randomly set aside to experimental groups (control, vehicle, and treatment received AA, treatment received AA and l-arginine or l-NAME). Ascorbic acid (1, 5 mg/kg) or saline injected intraperitoneally 2 weeks after CCI. Paw withdrawal threshold and response rate were assessed by a radiant heat and acetone spray test 30 and 60 min after injection. To investigate the possible implication of NO on the analgesic effect of 5 mg/kg of AA on the second week after CCI, 60 min after injection of saline or AA, animals received an intraperitoneal injection of l-arginine (500 mg/kg), or l-NAME (20 mg/kg) and behavioral tests achieved 20 min after on. Blood samples were collected from animal groups 2 weeks after the onset of treatment for evaluation of the activities of antioxidant defense system factors such as superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH), and catalase. At the same time, lipid hydroperoxide (LPO) as a prooxidant marker, and ascorbic acid concentration also determined in plasma. Single injection of 5 mg/kg but not 1 mg/kg of AA decreased pain symptoms in the second week after CCI (P < 0.001, F = 3, F = 3.2). Injection of 5 mg/kg AA alleviated the nociceptive effect of l-arginine and enhanced the analgesic effect of l-NAME and pain threshold was significantly altered in these two groups comparing the animals which received normal saline instead of AA (P < 0.001, P < 0.05, F = 2, F = 1.8, respectively). Ascorbic acid treatment (5 mg/kg) significantly improved oxidative damage as according to the decrease in the lipid peroxidation level (P < 0.01, F = 5), increasing in glutathione, glutathione peroxidase, and superoxide dismutase levels (P < 0.001, F = 11.25, F = 12.52, F = 5.65) and rising in catalase activity (P < 0.001, F = 4.7) and ascorbic acid (P < 0.001, F = 4.5) in plasma as compared with normal saline-treated rats. Data of this study implied the implication of nitric oxide pathway in defending effect of ascorbic acid against CCI-induced behavioral and biochemical changes in rats.

The Possible Role of Nitric Oxide Pathway in Pentylenetetrazole Preconditioning Against Seizure in Mice.

Preconditioning is defined as an induction of adaptive response in organs against lethal stimulation provoked by subsequent mild sublethal stress. Several chemical agents have been demonstrated to cause brain tolerance through preconditioning. The aim of the present study is to test the hypothesis that preconditioning with pentylenetetrazole (PTZ) may have protective effect against seizure induced by i.v. infusion of PTZ. Mice were preconditioned by low-dose administration of PTZ (25mg/kg) for 5 consecutive days, and the threshold of seizure elicited by i.v. infusion of PTZ was measured. To investigate the possible role of nitric oxide, NOS inhibitor enzymes, including L-NG-nitro-L-arginine methyl ester hydrochloride (L-NAME) (10mg/kg), aminoguanidine (AG) (50mg/kg), 7-nitroindazole (7-NI) (15mg/kg), and L-arginine (L-arg) (60mg/kg), were administered concomitantly with PTZ in both acute and chronic phases. Determination of seizure threshold revealed significant enhancement after preconditioning with low dose of PTZ. While the protective effect of PTZ preconditioning was enhanced after the administration of L-arg, it was reversed following administration of L-NAME and 7NI, suggesting the involvement of nitric oxide pathway as an underlying mechanism of PTZ-induced preconditioning. Preconditioning with PTZ led to brain tolerance and adaptive response in animal model of PTZ-induced seizure. This effect is in part due to the involvement of nitric oxide pathway.

The Effect of Chemerin on Cardiac Parameters and Gene Expressions in Isolated Perfused Rat Heart

Background:Chemerin is a novel chemoattractant adipokine expressed in cardiovascular system, and its receptor has been detected in the epicardial adipose tissue.Aims:To determine the effects of chemerin on the cardiac parameters and gene expressions in the isolated perfused rat heart.Study Design:Animal experiment.Methods:The hearts were retrogradely perfused with Langendorff technique to measure the cardiac parameters. The experimental groups were acutely treated with 10, 100, and 1000 nM doses of chemerin. Another group was given 10 μM L-nitric oxide synthase inhibitor for 5 min before 1000 nM chemerin administration. The real-time polymerase chain reaction was performed for detecting the expression of target genes.Results:All doses of chemerin significantly decreased the left ventricular developed pressure (max 35.33 Δ%, p<0.001), and +dP/dtmax (max 31.3 Δ%, p<0.001), which are the indexes of cardiac contractile force. In addition, 1000 nM chemerin reduced the coronary flow (max 31 Δ%, p<0.001). N(W)-nitro-L-arginine methyl ester antagonized the negative inotropic effect of chemerin on contractility. Chemerin induced a 2.16-fold increase in endothelial nitric oxide synthase mRNA and increased the cyclic guanosine monophosphate levels (p<0.001) but decreased the PI3Kγ gene expression (1.8-fold, p<0.001). Furthermore, all doses of chemerin decreased the CaV1.2 gene expression (1.69-fold, p<0.001).Conclusion:Acute chemerin treatment induces a negative inotropic action with the involvement of nitric oxide pathway, CaV1.2, and PI3Kγ on isolated rat heart.

Benzylidene Barbituric Acid Derivatives Shown Anticonvulsant Activity on Pentylenetetrazole-Induced Seizures in Mice: Involvement of Nitric Oxide Pathway

ABSTRACT Background: Barbituric acid derivatives have long been used as central nervous system (CNS) suppressants, such as sedatives, hypnotics and anticonvulsants. In addition, previous studies have implicated the involvement of nitric oxide (NO) in the anticonvulsive effects of barbiturates in CNS. Therefore, the purpose of this study was to figure out the effects of a novel class of barbituric acid derivatives on pentylenetetrazole (PTZ)-induced seizures in male mice. Methods: Thirteen synthesized barbituric acid derivatives (a-m) and phenobarbital were administered intraperitoneally (i.p.) 30 min before induction of seizures by PTZ administration. The mechanisms of PTZ-induced seizures in the mice was evaluated using a non-selective nitric oxide synthase (NOS) inhibitor, selective inducible NOS (iNOS) inhibitor, a selective neuronal NOS (nNOS) inhibitor, and NO substrate. Results: Administration of most of the above mentioned derivatives significantly increased the seizures threshold (P&lt;0.001). The most potent derivative (compound a), was chosen in order to investigate the mechanism of action involving in anticonvulsant activity. Administration of a non-selective NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) and a selective nNOS inhibitor, 7-nitroindazole (7-NI) reversed anticonvulsant activity of compound a. However, injection of the nitric oxide precursor, L-arginine (L-Arg) and a selective iNOS inhibitor, aminoguanidine (AG), did not change anticonvulsant activity of the mentioned compound. Conclusion: These results indicated that the NO system, specifically nNOS may contribute to the anticonvulsant activity of benzylidene barbituric acid derivative a. Therefore, this compound is a good candidate in order to designing new anticonvulsant medications

Anti-nociceptive mechanisms of flavonoids-rich methanolic extract from Terminalia coriacea (Roxb.) Wight & Arn. leaves

In view of the report on anti-nociceptive activity of Leathery Murdah, Terminalia coriacea {Roxb.} Wight & Arn. (Combretaceae) leaves, the present study was conducted to isolate the active constituents and identify the underlying mechanisms. The methanolic extract of T. coriacea leaves (TCLME) at doses 125, 250 and 500 mg/kg orally, was subjected to various in-vivo assays in acetic acid induced writhing and formalin induced paw-licking tests with aspirin (100 mg/kg) and morphine (5 mg/kg) as reference drugs. Three flavonoids, rutin, robinin and gossypetin 3-glucuronide 8-glucoside were isolated and characterized from TCLME for the first time. The extract showed significant (p < 0.001) dose-dependent anti-nociceptive activity in glutamate induced paw licking in mice. The involvement of opioid pathway was confirmed as naloxone (5 mg/kg, i.p) treatment blocked the analgesic activity of the test extract. Similarly, glibenclamide (an ATP - sensitive potassium channel inhibitor) at dose of 10 mg/kg, i.p increased writhing in acetic acid model. It reversed the inhibitory effects of TCLME when administered in combination. Treatment of TCLME alone and in combination with l-arginine (100 mg/kg, i.p) significantly (p < 0.001) reduced writhing while pre-treatment with l-NAME (20 mg/kg, i.p) further enhanced the analgesic action of TCLME indicating involvement of nitric oxide pathway.

Ex vivo immunomodulatory effect of ethanolic extract of propolis during Celiac Disease: involvement of nitric oxide pathway.

Celiac Disease (CeD) is a chronic immune-mediated enteropathy, in which dietary gluten induces an inflammatory reaction, predominantly in the duodenum. Propolis is a resinous hive product, collected by honeybees from various plant sources. Propolis is well-known for its anti-inflammatory, anti-oxidant and immunomodulatory effects, due to its major compounds, polyphenols and flavonoids. The aim of our study was to assess the ex vivo effect of ethanolic extract of propolis (EEP) upon the activity and expression of iNOS, along with IFN-γ and IL-10 production in Algerian Celiac patients. In this context, PBMCs isolated from peripheral blood of Celiac patients and healthy controls were cultured with different concentrations of EEP. NO production was measured using the Griess method, whereas quantitation of IFN-γ and IL-10 levels was performed by ELISA. Inducible nitric oxide synthase (iNOS) expression, NFκB and pSTAT-3 activity were analyzed by immunofluorescence assay. Our results showed that PBMCs from Celiac patients produced high levels of NO and IFN-γ compared with healthy controls (HC). Interestingly, EEP reduced significantly, NO and IFN-γ levels and significantly increased IL-10 levels at a concentration of 50µg/mL. Importantly, EEP downmodulated the iNOS expression as well as the activity of NFκB and pSTAT-3 transcription factors. Altogether, our results highlight the immunomodulatory effect of propolis on NO pathway and on pro-inflammatory cytokines. Therefore, we suggest that propolis may constitute a potential candidate to modulate inflammation during Celiac Disease and has a potential therapeutic value.

Pharmacological evidence of involvement of nitric oxide pathway in anti-pruritic effects of sumatriptan in chloroquine-induced scratching in mice.

Chloroquine (CQ) induces histamine-independent itch in human and mice. We recently reported the role of intradermal nitric oxide (NO)/cyclic guanosine monophosphate pathway in CQ-evoked scratching in mice. Chloroquine stimulates neuronal nitric oxide synthase (nNOS) activity to over-producing NO in the skin. Sumatriptan, a 5-hydroxytryptamine 1b/1d receptors (5-HTR1b/1d) agonist, is involved in pain and used to treat migraine and cluster headaches. According to previous studies, sumatriptan inhibits NOS activity. Thus, we aimed to investigate the effect of sumatriptan on CQ-induced scratching. We used the rostral back model of itch. Chloroquine was injected intradermally into the rostral back of NMRI mice, and the scratching behavior was evaluated by measuring the number of bouts over 30 min. We evaluated the effect of sumatriptan and combination of sumatriptan and a non-selective NO synthase inhibitor, L-N-nitro arginine methyl ester (L-NAME), on the scratching behavior. Additionally, the changes of skin, hippocampus, and cortical nitrite level after different treatments were studied. Intraperitoneal and intradermal sumatriptan attenuates CQ-induced itch which reversed by GR-127935, the selective 5-HTR1b and 5-HTR1d antagonist. Co-administration of subeffective doses of sumatriptan and L-NAME significantly decreases the scratching behavior. Intradermal injection of CQ significantly increases the intradermal nitrite levels while it does not have any significant effects on hippocampal or cortical nitrite concentrations. Likewise, the effective doses of intraperitoneal and intradermal sumatriptan significantly reduce intradermal nitrite levels. We concluded that sumatriptan suppresses CQ-induced itch most likely by activating 5-HT1b/1d receptors. This effect probably mediates through NO pathway.

Protective effect of spermine against pentylenetetrazole kindling epilepsy induced comorbidities in mice

Nitric oxide (NO), an important intracellular signaling molecule is involved in modulation of neuronal transmission. The NO level increases during epileptic activity in animal models of epilepsy. However, its role in epileptic activity remains controversial. Spermine is an endogenous polyamine; possesses anti-oxidant property and has ability to modulate ion channels and NO synthase activity. Therefore, the present study was designed to investigate the role of NO pathway in the neuroprotective effect of spermine, in Pentylenetetrazol (PTZ) induced kindling epilepsy in mice. PTZ (35mg/kg; intraperitoneal, i.p.) was administered on every alternate day up to 29days and challenge test was performed on 33rd day. From 15th day, spermine (5 and 10mg/kg; i.p.), L-NAME (10mg/kg; i.p), l-Arginine (50mg/kg; i.p) and sodium valproate (400mg/kg; i.p.) were administered up to 33rd day. Animals were sacrificed on 34th day for estimation of biochemical and neurotransmitters. Pretreatment with spermine, considerably, reversed the PTZ induced alterations. Further, pretreatment of L-NAME and l-Arginine with 5 and 10mg/kg; i.p. spermine, respectively, leads to an increase and decrease in its protective effects. The present study suggests the involvement of NO pathway in the protective effect of spermine against PTZ-induced kindling epilepsy in mice.

Minocycline attenuates cirrhotic cardiomyopathy and portal hypertension in a rat model: Possible involvement of nitric oxide pathway.

An increase in nitric oxide (NO) production has been reported in cirrhotic cardiomyopathy and, portal hypertension. Since minocycline has been shown to inhibit NO overproduction, we aimed to examine its role in a rat model of CCl4-induced cirrhotic cardiovascular complications. Portal pressure and inotropic responsiveness of isolated papillary muscles to isoproterenol were measured in cirrhotic rats, following minocycline (50 mg/kg/day for 8 weeks) treatment. Moreover, isolated papillary muscles were incubated with nonselective and selective nitric oxide synthase (NOS) inhibitors, N (ω)-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG) respectively, in an organ bath. Ventricular expression and localization of inducible NOS (iNOS), tumor necrosis factor-alpha (TNF-α) and serum nitrite concentration were evaluated. We found a decreased portal hypertension in minocycline-treated cirrhotic rats. Cirrhosis decreased contractility in response to isoproterenol stimulation, which was significantly attenuated by minocycline. Incubation with either L-NAME or AG reversed the impaired contractility in cirrhotic rats. Furthermore, minocycline decreased iNOS expression and localization in cardiomyocytes. A drop in serum nitrite and cardiac TNF-α level were also observed in cirrhotic rat that were treated by minocycline. The results suggest that minocycline may improve impaired cardiac contractility and hyperdynamic state in cirrhotic rats, and this effect could be mediated by NO-dependent mechanism.

Effects of short term and long term Extremely Low Frequency Magnetic Field on depressive disorder in mice: Involvement of nitric oxide pathway

AimsPrevious reports on the possible effects of Extremely Low Frequency Magnetic Fields (ELF MF) on mood have been paradoxical in different settings while no study has yet been conducted on animal behavior. In addition, it was shown that ELF MF exposure makes an increase in brain nitric oxide level. Therefore, in the current study, we aimed to assess the possible effect(s) of ELF MF exposure on mice Forced Swimming Test (FST) and evaluate the probable role of the increased level of nitric oxide in the observed behavior. Main methodsMale adult mice NMRI were recruited to investigate the short term and long term ELF MF exposure (0.5mT and 50Hz, single 2h and 2weeks 2h a day). Locomotor behavior was assessed by using open-field test (OFT) followed by FST to evaluate the immobility time. Accordingly, NΩ-nitro-l-arginine methyl ester 30mg/kg was used to exert anti-depressant like effect. Key findingsAccording to the results, short term exposure did not alter the immobility time, whereas long term exposure significantly reduces immobility time (p<0.01). However, it was revealed that the locomotion did not differ among all experimental groups. Short term exposure reversed the anti-depressant like effect resulting from 30mg/kg of NΩ-nitro-l-arginine methyl ester (p<0.01). SignificanceIt has been concluded that long term exposure could alter the depressive disorder in mice, whereas short term exposure has no significant effect. Also, reversing the anti-depressant activity of L-NAME indicates a probable increase in the brain nitric oxide.