Hanan S.M. Farghaly

Interleukin 13 Increases Contractility of Murine Tracheal Smooth Muscle by a Phosphoinositide 3-kinase p110δ-Dependent Mechanism

The Th2 cytokine interleukin (IL) 13 can elicit a number of responses consistent with a key role in the pathogenesis of asthma. We have used pharmacological and genetic approaches to demonstrate the role of signaling via the class I phosphoinositide 3-kinase p110δ isoform in IL-13-induced hyper-responsiveness of murine tracheal smooth muscle contractility in vitro. IL-13 treatment of tracheal tissue is associated with an early activation of phosphoinositide 3-kinase (PI3K), as assessed by phosphorylation of Akt. Tracheal smooth muscle contractility is enhanced by overnight incubation with IL-13, resulting in increased maximal contractions (Emax) to carbachol (CCh) and KCl. Inhibition of PI3K by the non-isoform-selective inhibitors wortmannin or 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), or the selective inhibitor of the PI3K p110δ isoform 2-(6-aminopurin-9-ylmethyl)-5-methyl-3-O-tolyl-3H-quinazolin-4-one (IC87114), prevented IL-13-induced hyper-responsiveness. Consistent with a role for PI3K p110δ in IL-13-induced hyper-responsiveness, IL-13 was unable to induce hyper-responsiveness in tissues from mice expressing the catalytically inactive form of p110δ (p110δD910A). These data indicate that IL-13 contributes to tracheal smooth muscle hyper-responsiveness via the PI3K p110δ isoform. In addition to previously reported effects on airway inflammation, inhibition of PI3K p110δ may be a useful target for the treatment of asthma by preventing IL-13-induced airway smooth muscle hyper-responsiveness.

Role of oxidative stress and inducible nitric oxide synthase in morphine-induced tolerance and dependence in mice. Effect of alpha-lipoic acid

In this study, the possible role of oxidative stress and nitric oxide (NO) synthase isoforms in the development of morphine tolerance and dependence, and effect of alpha-lipoic acid on these parameters were investigated in mice. The development of morphine tolerance as measured by the hot plate test and dependence, as assessed by naloxone-precipitated withdrawal manifestations, produced an increase in brain glutamate and malondialdehyde (MDA) levels and NO production as well as a decrease in brain intracellular reduced glutathione (GSH) level and glutathione peroxidase (GSH-Px) activity. Also, the development of these syndromes increased inducible but not neuronal NO synthase mRNA and protein expressions in mice brain. Co-administration of alpha-lipoic acid (α-LA) inhibited the development of morphine tolerance and dependence, their associated biochemical alterations, except elevation of brain glutamate level, and their associated increase in brain inducible NO synthase mRNA and protein expressions. The inhibitory effect of α-LA on morphine-induced tolerance and dependence and on naloxone-induced biochemical alterations in morphine-dependent mice was enhanced by concurrent administration of the NMDA receptor antagonist, dizocilpine, the antioxidant, N-acetylcysteine or the selective inducible NO synthase inhibitor, aminoguanidine. On the other hand, this inhibitory effect of α-LA was not changed by concurrent administration of the selective neuronal NO synthase inhibitor, 7-nitroindazole but antagonized by concurrent administration of the NO precursor, L-arginine. These results suggest that α-LA through inhibition of morphine-induced oxidative stress and increase in the expression and activity of inducible NO synthase in the brain can attenuate the development of morphine tolerance and dependence.

Comparative evaluation of the effect of tricyclic antidepressants on inducible nitric oxide synthase expression in neuropathic pain model

The analgesic effect of acute i.p. administration of amitriptyline (norepinepherine and serotonin reuptake inhibitor), clomipramine (serotonin reuptake inhibitor) and desipramine (norepinepherine reuptake inhibitor) was studied in chronic constriction injury (CCI) model of sciatic nerve in rats and mRNA and protein expression of inducible nitric oxide synthase (iNOS) were also investigated. Acute treatment with amitriptyline and clomipramine produced antinociceptive effects after sciatic nerve injury and blockade of norepinephrine reuptake using desipramine did not demonstrate antinociceptive effects. The antinociceptive effect of amitriptyline, not clomipramine, was augmented by the selective iNOS inhibitor, aminoguanidine. Amitriptyline inhibited iNOS mRNA and protein expression in cerebellum and hippocampus. However, desipramine altered neither iNOS expression at mRNA level nor at post-transcriptional level. Based on our experimental findings, we conclude that the analgesic effect of the dual norepinepherine and serotonin reuptake inhibitor, amitriptyline, is partially due to inhibition of central iNOS.

Involvement of glutamate, oxidative stress and inducible nitric oxide synthase in the convulsant activity of ciprofloxacin in mice

This study investigated the potential convulsive activity of ciprofloxacin in mice and the possible mechanism(s) of this activity. Intraperitoneal (i.p.) administration of ciprofloxacin into mice resulted in convulsive seizures in a dose-dependent manner. The clonic median convulsant dose (CD(50)) of ciprofloxacin in mice was increased by pretreatment with dizocilpine, alpha-lipoic acid or aminoguanidine, not changed by pretreatment with 7-nitroindazole and decreased by pretreatment with L-arginine and fenbufen. The increase in nitric oxide (NO) production and malondialdehyde (MDA) level as well as the decrease in intracellular reduced glutathione (GSH) level and glutathione peroxidase (GSH-Px) activity induced by the estimated clonic CD(50) of ciprofloxacin in mice brain was inhibited by pretreatment with dizocilpine, alpha-lipoic acid or aminoguanidine. These biochemical alterations were not changed by pretreatment with 7-nitroindazole but enhanced by pretreatment with L-arginine. The elevation induced by the clonic CD(50) of ciprofloxacin in brain glutamate level was not changed by pretreatment with MK-801, alpha-lipoic acid, aminoguanidine or L-arginine. Combined treatment of mice with fenbufen and ciprofloxacin produced elevation of brain NO production and glutamate and MDA levels as well as inhibition of brain intracellular GSH level and GSH-Px activity. In addition, i.p. administration of the clonic CD(50) of ciprofloxacin produced an increase in inducible but not in neuronal NO synthase mRNA and protein expressions in mice brain. These results suggest that elevation of brain glutamate levels with consequent oxidative stress and increase in the expression and activity of brain inducible NO synthase may play a pivotal role in ciprofloxacin-induced convulsive seizures.

Effect of dexmedetomidine and cold stress in a rat model of neuropathic pain: Role of interleukin-6 and tumor necrosis factor-α.

Dexmedetomidine (Dex) is a novel Alpha 2-adrenoceptor agonist. It decreases sympathetic tone and attenuates the stress responses to anesthesia and surgery. People exposed to cold suffer unpleasant thermal pain, which is experienced as stress and causes the release of noradrenaline from the sympathetic terminals. The present study investigated the effects of cold stress and dexmedetomidine on chronic constriction injury (CCI) model of the sciatic nerve in rats. Sixty four male Wistar rats were divided into seven groups of eight rats each: repeated cold stress (RCS) group, sham RCS group, CCI group, sham CCI group, Dex-treated group received a single dose of Dex (5 μg/kg), CCI+Dex group, CCI+RCS group. Interleukin-6 (IL-6) and tumor necrosis factor- alpha (TNF-α) levels in the serum were measured by enzyme-linked immunosorbent assay. The mean body weight of CCI, RCS, CCI+RCS, CCI+Dex and RCS+Dex groups decreased significantly compared with pre-values. Dexmedetomidine and CCI caused significant changes of the systolic, diastolic and mean blood pressure. Both RCS and CCI groups showed significant decreased of reaction time in the hot plate test. The RCS and CCI groups demonstrated a significant mechanical hyperalgesia, while pain threshold was increased in the RCS+Dex group. A significant decrease of serum IL-6 and TNF-α was demonstrated in CCI+RCS and CCI+Dex groups. The therapeutic effectiveness of dexmedetomidine in neuropathic pain may be through inhibition of proinflammatory cytokines, primarily IL-6 and TNF-α. Moreover, cold stress may result in increased resistance to neuropathic pain.

A potential mechanism for the ameliorative effect of thymoquinone on pentylenetetrazole-induced kindling and cognitive impairments in mice.

Cognitive dysfunction is commonly observed in epileptic patients. Pentylenetetrazole (PTZ) kindling is a well established animal model which simulates clinical epilepsy. This study evaluated the potential role of glutamate, oxidative stress and nitric oxide (NO) overproduction in pentylenetetrazole (PTZ)-induced kindling and associated cognitive impairments in mice and effect of thymoquinone on these parameters. Repeated treatment of mice with a subconvulsive dose of PTZ (35mg/kg i.p.) once every alternate-day for 12 injections induced kindling. PTZ-kindled mice showed learning and memory impairments as assessed by acquisition and probe trials of Morris water maze and step-through latency of passive avoidance tests. Concurrently, the brain glutamate, malondialdehyde and nitrite levels were increased while the brain intracellular reduced glutathione level and glutathione peroxidase activity were decreased in PTZ-kindled mice. Also, the brain inducible but not neuronal NO synthase mRNA and protein expressions were increased in PTZ-kindled mice. Treatment of mice with thymoquinonne (5, 10 and 20mg/kg i.p.) along with alternate-day subconvulsive dose of PTZ produced dose-dependent protection against PTZ-induced kindling and learning and memory impairments. Moreover, treatment of mice with thymoquinonne (20mg/kg) inhibited the biochemical alterations induced by PTZ in the brain except the elevation of brain glutamate level. The associated increase in brain inducible NO synthase mRNA and protein expressions were also inhibited. These results suggest that glutamate, and subsequent oxidative stress and NO overproduction, via inducible NO synthase, play an important role in the pathophysiology of PTZ-induced kindling and cognitive impairments in mice. Thymoquinone dose-dependently protects against PTZ-induced kindling and cognitive impairments. Inhibition of PTZ-induced brain oxidative stress and NO overproduction, via increase the expression and activity of inducible NO synthase, may play an important role in thymoquinone action.

Novel N-substituted 5-aminosalicylamides as dual inhibitors of cyclooxygenase and 5-lipoxygenase enzymes: Synthesis, biological evaluation and docking study

Three new series of 5-aminosalicylic acid derivatives; series I (14, 16-18), series II (19-30) and series III (31-41) were synthesized as potential dual COX-2/5-LOX inhibitors. Their chemical structures were confirmed using spectroscopic tools including IR, 1H NMR, 13C NMR, mass spectroscopy and elemental analyses. The anti-inflammatory activity for all target compounds was evaluated in vivo using carrageenan-induced paw edema. Compound 36 showed the highest anti-inflammatory activity (114.12%) relative to reference drug indomethacin at 4 h interval. Selected derivatives were evaluated in vitro to inhibit ovine COX-1, human recombinant COX-2 and 5-LOX enzymes. Compounds 34 &35 exhibited significant COX-2 inhibition (IC50 = 0.10 µM) with significant COX-2 selectivity indices (SI = 135 & 145 respectively) approximate to celecoxib (IC50 = 0.049 µM, SI = 308.16) and exceeding indomethacin (IC50 = 0.51 µM, SI = 0.08). Interestingly, all compounds showed superior 5-LOX inhibitory activity about 2-5 times relative to zileuton. Compound 16 was the superlative 5-LOX inhibitor that revealed (IC50 = 3.41 µM) relative to zileuton (IC50 = 15.6 µM). Compounds 34, 35, 36 and 41 showed significant dual COX-2/5-LOX inhibitions. The gastric ulcerogenic effect of compound 36 was examined on gastric mucosa of albino rats and they showed superior GI safety profile compared with indomethacin. Molecular docking studies of the compounds into the binding sites of COX-1, COX-2 and 5-LOX allowed us to shed light on the binding mode of these novels dual COX and 5-LOX inhibitors.

Protective effect of the standardized extract of ginkgo biloba (EGb761) against hypertension with hypercholesterolemia-induced renal injury in rats: Insights in the underlying mechanisms

The potential protective role of the standardized leaf extract of ginkgo biloba (EGb761) on hypertension with hypercholesterolemia-induced renal injury was investigated in rats. Hypertension was induced by L-N(G)-nitroarginine methyl ester (L-NAME) and hypercholesterolemia was induced by feeding rats with a diet containing 1% cholesterol. In these animals repeated treatment with EGb761 produced a progressive reduction in the systolic, diastolic and mean arterial blood pressure (BP). EGb761 increased the progressive reduction in the systolic, diastolic and mean arterial BP induced by repeated administration of losartan with simvastatin. EGb761 corrected the compromised serum lipid profile and enhanced the effect of losartan with simvastatin on lipid profile. EGb761 protected against hypertension with hypercholesterolemia-induced renal injury as assessed by measurement of serum renal function markers and by histopathological examination. EGb761 enhanced the renoprotective effect of losartan with simvastatin in these rats. Concomitantly, hypertension with hypercholesterolemia-induced elevation of renal tissue malondialdehyde (MDA) and nitrite levels and reduction of intracellular reduced glutathione (GSH) level were inhibited by repeated treatment with EGb761. In addition, hypertension with hypercholesterolemia-induced increases in tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) levels in renal tissues were inhibited by treatment with EGb761. Also, EGb761 inhibited hypertension with hypercholesterolemia-induced decrease in endothelial nitric oxide synthase (eNOS) protein expression and increase in the protein expressions of inducible NO synthase (iNOS), TNF-α, IL-6 and IL-1β in the kidney tissues. Losartan with simvastatin produced similar effects on renal tissues oxidative stress, nitrite and inflammatory markers levels and on protein expressions of eNOS, iNOS, TNF-α, IL-6 and IL-1β. EGb761 enhanced losartan with simvastatin effects. These results indicate that EGb761 has the ability to protect against hypertension with hypercholesterolemia-induced renal injury. The ability of EGb761 to provide this renoprotective effect may positively correlate, besides its antihypertensive and antihypercholesterolemic effects, to its ability to suppress renal oxidative stress, nitrosative stress and inflammation.

Inhibition of adiposity and related metabolic disturbances by polyphenol-rich extract of Boswellia serrata gum through alteration of adipo/cytokine profiles

BackgroundThe role of proinflammatory cytokines in adiposity is well established. The anti-inflammatory and antihyperglycemia effects of Boswellia serrata (B. Serrata) gum have been demonstrated by many investigators. The present study aimed to investigate the anti-obesity potential of B. serrata extract.MethodsThe effects of B. serrata extract on lipase activity and acute food intake were investigated. The present study aimed to investigate the anti-obesity potential of B. serrata extract. The effects on lipase activity and acute food intake were investigated. Body weight changes, biochemical and histopathological markers were demonstrated in rats fed a high-fat diet.ResultsBoswellia serrata extract inhibited alterations in pancreatic lipase activity, but orlistat was more efficacious. B. serrata and ephidrene, but not orlistat, significantly suppressed cumulative food intake in mice. In obese rats, B. serrata or orlistat significantly decreased weight gain and weight of visceral white adipose tissue. B. serrata-treated animals exhibited a significant reduction in serum glucose, TC, TG, LDL-C, FFA, IL-1β, TNF-α, insulin and leptin levels of obese rat groups while HDL-C and adiponectin levels were significantly increased by orlistat or B. serrata extract. Histopathological examination of the liver revealed that B. serrata was more effective than orlistat in alleviating steatosis and adipocyte hypertrophy shown in obese control rats.ConclusionsBoswellia serrata is as effective as orlistat in preventing obesity, hyperlipidemia, steatosis and insulin resistance. These actions may be mediated by suppression of food intake and decrease levels of TNF-α, IL-1β and leptin resistance along with increasing adiponectin.

Cortical excitability in tramadol dependent patients: A transcranial magnetic stimulation study

BACKGROUND Addiction to tramadol, a widely used analgesic, is becoming increasingly common. Tramadol can also induce seizures even after a single clinical dose. We tested whether the epileptogenicity of tramadol was associated with any changes in cortical excitability and inhibitory transmission using transcranial magnetic stimulation (TMS). METHODS The study included 16 tramadol dependent patients and 15 age and sex matched healthy volunteers. Clinical evaluation was conducted using an addiction severity index. TMS assessment of excitability was conducted on the motor cortex since the response to each TMS pulse at that site is easily measured in terms of the amplitude of the twitches it evokes in contralateral muscles. Measures included resting and active motor threshold (RMT and AMT respectively), motor evoked potential (MEP) amplitude, cortical silent period (CSP) duration, transcallosal inhibition (TCI), and short interval intracortical inhibition and facilitation (SICI and ICF respectively). Urinary level of tramadol was measured immediately before assessing cortical excitability in each patient. RESULTS RMT and AMT were significantly lower, the duration of the CSP was shorter and SICI was reduced in patients compared with the control group. These findings are suggestive of increased neural excitability and reduced GABAergic inhibition following exposure to tramadol. Also there were negative correlations between the severity of tramadol dependence and a number of cortical excitability parameters (AMT, RMT, and CSP with P=0.002, 0.005, and 0.04 respectively). CONCLUSIONS The results provide evidence for hyperexcitability of the motor cortex coupled with inhibitory deficits in tramadol dependent patients.