Mahran S. Abdel-Rahman

Protective effect of Nigella sativa oil against tramadol-induced tolerance and dependence in mice: role of nitric oxide and oxidative stress.

Nigella sativa seed extracts and its oil have been exploited for their various health benefits. In this study, the effects of N. sativa oil on tramadol-induced tolerance and dependence and possible mechanism(s) of these effects were investigated, for the first time, in mice. Repeated administration of N. sativa oil (4 ml/kg, p.o.) along with tramadol (50mg/kg, s.c.) inhibited the development of tramadol tolerance, as measured by the hot plate test, and dependence as assessed by naloxone (5mg/kg, i.p.)-precipitated withdrawal manifestations. Concomitantly, nitric oxide overproduction and increase in brain malondialdehyde level induced by repeated administration of tramadol to mice or by administration of naloxone to tramadol-dependent mice were inhibited by co-administration of the oil. Also, the decrease in brain intracellular reduced glutathione level and glutathione peroxidase activity induced by both treatments was inhibited by co-administration of the oil. The increase in brain glutamate level induced by both treatments was not inhibited by concurrent administration of the oil. The inhibitory effect of N. sativa oil on tramadol-induced tolerance and dependence was enhanced by concurrent i.p. administration of the NMDA receptor antagonist, dizocilpine (0.25mg/kg). Also, the inhibitory effect of the oil on naloxone-induced biochemical alterations in tramadol-dependent mice was enhanced by concurrent administration of dizocilpine. Similarly, concurrent i.p. administration of the NO synthase inhibitor, L-N(G)-nitroarginine methyl ester (10mg/kg) or the antioxidant, N-acetylcysteine (50mg/kg) enhanced these inhibitory effects of N. sativa oil. On the other hand, these effects were antagonized by concurrent i.p. administration of the NO precursor, L-arginine (300 mg/kg). These results provide evidence that N. sativa oil appears to have a therapeutic potential in tramadol tolerance and dependence through blockade of NO overproduction and oxidative stress induced by the drug.

Effect of propofol on perception of pain in mice: mechanisms of action.

The latencies of pain threshold to different subhypnotic doses (12.5, 25 and 50 mg kg-1) of propofol, an anaesthetic, administered intraperitoneally (i.p.) into male mice were measured using a hot plate method. The possible mechanism of pain control by propofol was also investigated through blocking beta-endorphin receptors and measuring serum level of beta-endorphin. Morphine (1.5 mg kg-1; i.p.) was used as a reference of reduction of pain sensation. The results showed that propofol in doses of 25 and 50 mg kg-1 significantly (P < 0.01) increased the latency of pain threshold but a lower dose (12.5 mg kg-1) failed to produce any significant change. This indicates that propofol reduced pain and this effect is dose-dependent. Propofol prevents hyperalgesia produced by prostaglandin PGE2, (0.5 mg kg-1, i.p.; P < 0.01). Pretreatment with naloxone (1.0 mg kg-1, i.p.) abolished significantly (P < 0.01) the antinociceptive action of propofol. Furthermore, serum level of beta-endorphin was increased (P < 0.01) after propofol injection particularly at the peak time of propofol action. The serum level of corticosterone was also increased (P < 0.01) at the time of beta-endorphin release. It was concluded that propofol can control pain and this action may be centrally modulated through the opioid system rather than at the level of the spinal cord.

Reactive oxygen and nitrogen species in patients with rheumatoid arthritis as potential biomarkers for disease activity and the role of antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have distinct contribution to the destructive, proliferative synovitis of rheumatoid arthritis (RA) and play a prominent role in cell-signaling events. However, few studies had clarified the role of individual ROS and RNS in the etiopathogenesis of RA. To date, most of the studies were concerned with the measurement of the total oxidative and nitrative stress levels in RA. The aim of this study was to monitor the levels of individual ROS and RNS to emphasize the role that each plays in the pathogenesis of RA and their usefulness as possible biomarkers for the disease activity. In addition, the effect of an antioxidant (ascorbic acid), added to the treatment regimen, on the levels of ROS, RNS and disease activity has been evaluated. Forty-two Saudi RA patients and 40 healthy controls of both genders were included in this study. Serum levels of six different ROS and three different RNS were measured using specific fluorescent probes. The ROS included the hydroxyl radical ((•)OH), the superoxide anion (O2(•-)), hydrogen peroxide (H2O2), the singlet oxygen ((1)O2), the hypochlorite radical (OHCl(•)), and the peroxyl radical (ROO(•)). The RNS included nitric oxide (NO(•)), nitrogen dioxide (ONO-) and peroxynitrite (ONOO-). The main clinical and biochemical markers for disease activity were assessed and correlated with ROS and RNS levels. The clinical markers included the 28 swollen joint count (SJC-28), the 28-tender joint count (TJC-28), morning stiffness and symmetric arthritis, in addition to the disease activity score assessing 28 joints with erythrocyte sedimentation rate (DAS28-ESR). The biochemical markers included undercarboxylated osteocalcin (ucOC), matrix metalloproteinase (MMP-3), ESR, C-reactive protein (CRP), rheumatoid factor (RF) and anticyclic citrullinated polypeptide (Anti-CCP). Ascorbic acid (1mg/day) was added as an antioxidant to the regular treatment regimen of RA patients for two months, and the levels of ROS and RNS, as well as disease activity were re-evaluated. The results have shown significant higher serum levels of individual ROS and RNS in RA patients compared with healthy subjects. Moreover, this study might be the first to report strong positive correlations between most of the reactive species and the clinical and biochemical markers of RA. Interestingly, the addition of ascorbic acid had significantly reduced the levels of all ROS and RNS in RA patients. In conclusion, the role of oxidative and nitrative stress in the pathogenesis of RA has been confirmed by this study. Serum levels of ROS and RNS may effectively serve as biomarkers for monitoring disease progression. Finally, the addition of an antioxidant, such as ascorbic acid, in the management of RA may be of a great value.

Synthesis of new 4,5-3(2H)pyridazinone derivatives and their cardiotonic, hypotensive, and platelet aggregation inhibition activities

Abstract4,5-dihydro-3(2H)pyridazinones such as CI-914, CI-930 and pimobendan along with tetrahydropyridopyridazine (endralazine) and perhydropyridazinodiazepine (cilazopril) have been used as potent positive inotropes, antihypertensives as well as platelet aggregation inhibitors. Accordingly, the present work involves the synthesis of 24 target compounds; 4,5-dihydro-3(2H)pyridazinones in addition to seven reported intermediates. The chemical structures of the new compounds were assigned by microanalysis, IR, 1H-NMR spectral analysis and some representatives by mass spectrometry. The positive inotropic effect of the final compounds and the intermediates 12a–12d as well as the reported intermediate compound 10 was determined in-vitro on isolated rabbit heart in comparison to digoxin. Data obtained revealed that twelve of the test compounds exhibited higher effective response than digoxin, nine compounds elicited comparable effects to digoxin and eight compounds were less active than digoxin. In addition, four compounds approved marked significant hypotensive effect better than that of the previously reported compound 10. Moreover, two compounds induced complete platelet aggregation inhibition. The last two compounds were also subjected to determination of their LD50 and they showed no signs of toxicity up to the dose level 300 mg/kg (i.p.), while the reported oral LD50 of digoxin is 17.78 mg/kg. Correlation of cardiotonic and hypotensive activities with structures of compounds was tried and pharmacophore models were computed to get useful insight onto the essential structural features required for inhibiting phosphodiesterase-III in the heart muscles and blood vessels.

Menaquinone-7 as a novel pharmacological therapy in the treatment of rheumatoid arthritis: A clinical study

Menaquinones (MKs) have been reported to induce apoptosis in rheumatoid arthritis (RA) synovial cells. Recently, menaquinone-4 (MK-4) was proven as a new potential agent for the treatment of RA. However, menaquinone-7 (MK-7) has greater bioavailability and efficacy than MK-4 after oral administration. Yet, the therapeutic benefits of MK-7 in the management of patients with RA have never been addressed. This study was designed to clarify the therapeutic role of MK-7 added to normal therapeutic regimen of RA in patients with different stages of the disease with a clinical follow up through a randomized clinical trial. In a cross sectional study, 84 RA patients (24 male, 60 female) (average age=47.2 years) were enrolled in this study. The patients were divided into MK-7 treated group (n=42) and MK-7 naïve group (n=42). MK-7 capsules were administered in a dose of 100µg/day for three months in the first group without changing in other medications. The clinical and biochemical markers on RA patients treated with MK-7 and naïve group were assessed. In MK-7 treated group, serum concentrations of MK-7 were monitored before and after three months of MK-7 administration. In the cross sectional study, a significant decrease in MK-7 treated group for the levels of undercarboxylated osteocalcin (ucOC), erythrocyte sedimentation rate (ESR), disease activity score assessing 28 joints with ESR (DAS28-ESR), C-reactive protein (CRP) and matrix metalloproteinase (MMP-3) was found. In MK-7 treated group, a marked decrease in RA clinical and biochemical markers for moderate and good response compared to non-responders was observed in ucOC, ESR and DAS28-ESR. A marked increase in the levels of MK-7 for the moderate and good responders compared to non-responders was observed. The results suggest that MK-7 improves disease activity in RA patients. Therefore, MK-7 represents a new promising agent for RA in combination therapy with other disease modifying antirheumatic drugs.

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.

Effect of d,l-verapamil, verapamil enantiomers and verapamil metabolites on the binding of vincristine to α1-acid glycoprotein

Vincristine binding to solutions of alpha 1-acid glycoprotein (AGP, 2 mg/ml) and the effect of D,L-verapamil, verapamil enantiomers and the verapamil metabolites norverapamil and D617 were investigated in vitro using equilibrium dialysis and 3H-labelled vincristine. Vincristine binding to AGP (52.3 +/- 3.6%) was concentration independent over the range 0.002-2.0 micrograms/ml. The displacement of vincristine from AGP varied between 25.1 and 81.3% with D,L-verapamil and verapamil enantiomers added at concentrations in the range 5-50 micrograms/ml. In contrast, the displacement by D617 (5-100 micrograms/ml) was weaker and varied between 0 and 47%. The displacement at 20 micrograms/ml produced by D,L-verapamil, R-verapamil, S-verapamil and norverapamil was 53.1%, 56.8%, 58.9% and 53.9%, respectively, was more than double that for D617 (25%; P = 0.002). It is concluded that vincristine, D,L-verapamil and verapamil isomers and metabolites interact at binding sites on AGP. These interactions may be clinically important in multidrug resistance, for example in cancer patients with elevated levels of AGP undergoing treatment with verapamil and vinca alkaloids.

Protective effect of citicoline against aluminum-induced cognitive impairments in rats.

The potential protective effect of citicoline on aluminum chloride-induced cognitive deficits was investigated in rats. In a Morris water maze, administration of aluminum chloride to rats for 90 days resulted in increased escape latency to reach the platform and decreased swimming speed in acquisition trials. Similarly, in probe trials, the time required to reach the hidden platform was increased and the time spent in the target quadrant was reduced. Also, administration of aluminum chloride to rats for 90 days increased the reference and working memory errors and time required to end the task in the radial arm maze. In addition, this treatment decreased the step-through latency in the passive avoidance test. Concurrently, treatment of rats with aluminum chloride for 90 days increased hippocampal glutamate, malondialdehyde, and nitrite levels and decreased intracellular reduced glutathione level. In the citicoline-treated group, aluminum chloride-induced learning and memory impairments as assessed by the Morris water maze, radial arm maze, and passive avoidance tests were inhibited. At the same time, treatment of rats with citicoline prevented the biochemical alterations induced by aluminum chloride in the hippocampus. It can be concluded that elevation of hippocampal glutamate level with consequent oxidative stress and nitric oxide (NO) overproduction may play an important role in aluminum-induced cognitive impairments. Also, our results suggest, for the first time, that citicoline can protect against the development of these cognitive deficits through inhibition of aluminum-induced elevation of glutamate level, oxidative stress, and NO overproduction in the hippocampus.