Abdel-Raheim M.A. Meki

Oxidative stress in streptozotocin-induced diabetic rats: effects of garlic oil and melatonin

In the present study, oxidative stress in diabetic model and the effect of garlic oil or melatonin treatment were examined. Streptozotocin (60 mg/kg body weight, i.p.)-induced diabetic rats, showed a significant increase of plasma glucose, total lipids, triglyceride, cholesterol, lipid peroxides, nitric oxide and uric acid. Concomitantly, significant decreases in the levels of antioxidants ceruloplasmin, albumin and total thiols were found in the plasma of diabetic rats. Lipid peroxide levels were significantly increased in erythrocyte lysate and in homogenates of liver and kidney, while superoxide dismutase (SOD) activities were decreased in tissue homogenates of liver and kidney. Treatment of diabetic rats with garlic oil (10 mg/kg i.p.) or melatonin (200 microg/kg i.p.) for 15 days significantly increased plasma levels of total thiol, ceruloplasmin activities, albumin. Lipid peroxides, uric acid, blood glucose, total lipid, triglyceride and cholesterol were decreased significantly after treatment with garlic oil or melatonin. Nitric oxide levels were decreased significantly in rats treated with melatonin only. In erythrocytes lysate, glutathione S-transferase (GST) activities were increased significantly in rats treated with garlic oil or melatonin, while lipid peroxides decreased significantly and total thiol increased significantly in melatonin or garlic oil treatment, respectively. In liver homogenates of rats treated with garlic or melatonin, lipid peroxides were decreased significantly, and GST activities increased significantly, while SOD activities were increased significantly in liver and kidney after garlic or melatonin treatment. The results suggest that garlic oil or melatonin may effectively normalize the impaired antioxidants status in streptozotocin induced-diabetes. The effects of these antioxidants of both agents may be useful in delaying the complicated effects of diabetes as retinopathy, nephropathy and neuropathy due to imbalance between free radicals and antioxidant systems. Moreover, melatonin may be more powerful free radical scavenger than garlic oil.

Melatonin reduces oxidative stress induced by ochratoxin A in rat liver and kidney.

Melatonin (MEL) displays antioxidant and free radical scavenger properties. In the present study, the effect of MEL on the oxidative stress induced by ochratoxin A (OTA) administration in rats was investigated. Four groups of 15 rats each were used: controls, MEL-treated rats (5 mg/kg body mass), OTA-treated rats (250 microg/kg) and MEL+OTA-treated rats. After 4 weeks of treatment, the levels of malondialdehyde (MDA), a lipid peroxidation product (LPO) were measured in serum and homogenates of liver and kidney. Also, the levels of glutathione (GSH), and activities of glutathione reductase (GR), glutathione peroxidase (GSPx), superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) in liver and kidney were determined. In OTA-treated rats, the levels of LPO in serum and in both liver and kidney were significantly increased compared to levels in controls. Concomitantly, the levels of GSH and enzyme activities of SOD, CAT, GSPx and GR in both liver and kidney were significantly decreased in comparison with controls. In rats received MEL+OTA, the changes in the levels of LPO in serum and in liver and kidney were not statistically significant compared to controls. Concomitantly, the levels of GSPx, GR and GST activities in both liver and kidney tissues were significantly increased in comparison with controls. Similar increases in GSPx, GR and GST activities were also observed in MEL-treated rats when compared with controls. In conclusion, the oxidative stress may be a major mechanism for the toxicity of OTA. MEL has a protective effect against OTA toxicity through an inhibition of the oxidative damage and stimulation of GST activities. Thus, clinical application of melatonin as therapy should be considered in cases of ochratoxicosis.

Serum interleukin-1β, interleukin-6, nitric oxide and α1-antitrypsin in scorpion envenomed children

During the present study, thirty-eight children in Upper Egypt (less than 12years old) were admitted to Pediatric Intensive Care Unit for scorpion envenomation. They were compared with thirteen apparently healthy children of matching age as controls. The victims and controls were subjected to complete clinical examination and full blood count. The evaluations of the serum levels of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), nitric oxide (NO) and alpha1-antitrypsin (alpha1-AT) were performed once for the controls and twice for the victims, the first sample on admission and the 2nd sample after 24 h. All victims showed significantly higher mean values of IL-1beta IL-6, NO, alpha1-AT and leucocytic count both on admission and on follow up when compared with controls. Manifestations of mild envenomation were detected among 28.9% of the victims, while 71.1% of the victims manifested severe scorpion envenomation. The severely envenomated children showed significantly higher mean values of IL-1beta, IL-6, NO, alpha1-AT and leucocytic count both on admission and on follow up when compared with mild cases. The case fatality rate in the current study was 7.8%. The non-surviving victims showed significantly higher mean values of IL-1beta, IL-6 and leucocytic count both on admission and on follow up in comparison to the survivors. Furthermore, those fatal cases showed a non-significant decline in the studied biochemical indices on follow up after 24 h, while the survivors showed a significant decline in the serum levels of IL-6, IL-1beta, NO and alpha1-AT after 24h of post arrival to the hospital. In conclusion, these data revealed that cytokines are involved in the pathogenesis of scorpion envenomation and correlated with the severity of envenomation. This may provide a rationale for anticytokine treatment.

A bradykinin-potentiating peptide (peptide K12) isolated from the venom of Egyptian scorpion Buthus occitanus

A nontoxic peptide with bradykinin-potentiating activity was isolated from the dialyzed venom of the scorpion Buthus occitanus by reverse-phase high performance liquid chromatography (RP-HPLC). The pharmacological activity of the peptide was bioassayed by its ability to potentiate added bradykinin (BK) on the isolated guinea pig ileum as well as the isolated rat uterus for contraction. Moreover, the peptide potentiates in vivo the depressor effect of BK on arterial blood pressure in the normotensive anesthetized rat. Chemical characterization of the peptide was also performed. The amino acid composition of the peptide showed 21 amino acid residues per molecule including three proline residues. The amino acid sequence of the purified peptide was confirmed by mass spectrometry. Either N- or C-terminal ends were free. The sequence does not show a homology with bradykinin-potentiating peptides isolated from either scorpion or snake venoms. Furthermore, we did not find a significant sequence homology between the sequence of the isolated peptide and any of proteins or peptides in GenPro or NBRF data banks. The peptide also inhibited angiotensin-converting enzyme (ACE), and could not serve as substrate for the enzyme. It could be concluded that the mechanism of bradykinin-potentiating peptide (BPP) activity may be due to ACE inhibition.

Ameliorated effects of green tea extract on lead induced liver toxicity in rats.

In the present study, the effect of green tea extract (GTE) on lead induced toxicity was studied in Sprague-Dawley rats. Four groups of rats were used in the study. Lead and GTE was given orally to the rats with drinking water for 8 weeks. Lead concentration in the digested tissues of liver was detected using atomic absorption spectroscopy. The activities of glutathione-S-transferase (GST) and superoxide dismutase (SOD) were used as markers to evaluate the anti oxidant status of tissues. Lead exposure was found to attenuate the antioxidant potential of liver, which was however augmented when supplemented with green tea extract. Liver enzymes ALT, AST and ALP and serum protein determinations indicated the protective effects of green tea extract. Histopathological studies of liver revealed that supplementation of green tea extract resulted in mild degeneration and congestion of the blood vessels and an enhanced regenerative capacity.

The biochemical and morphological alterations following administration of melatonin, retinoic acid and Nigella sativa in mammary carcinoma: an animal model

Worldwide, breast cancer is the second leading cause of cancer death among women and the third most common cancer. Although our understanding of the molecular basis of this fatal disease has improved, this malignancy remains elusive. Melatonin (Mel), retinoic acid (RA) and Nigella sativa (NS) are substances with anticancer effects. To date, our understanding of the mechanisms of therapeutic effects of these products in mammary cancer is still marginal. To look at the preventive and therapeutic values of these products, we carried out this investigation. An animal model formed of 80 rats was established. The animals were divided into eight groups of 10 animals each: (a) control group injected with the same vehicle used for treatments in the relevant dosages and routes; (b) carcinogen group injected with the known carcinogenic substance 7,12‐di‐methylbenz(a)anthracene (DMBA) that induces mammary carcinoma; (c) three prophylactic (Pro) groups (Mel‐Pro, RA‐Pro and NS‐Pro) injected with test substances (Mel, RA and NS, respectively) 14 days before the intake of the carcinogenic substance DMBA and then continued until the end of the experiments; and (d) three treated (Tr) groups (Mel‐Tr, RA‐Tr and NS‐Tr) injected with the vehicles after the intake of DMBA. In both the Pro and Tr groups, the drugs were daily administered for 3 months. The animals were killed, and their serum and tissues were evaluated for (a) markers of tumorigenicity [serum levels of total sialic acid (TSA) and lipid‐bound sialic acid (LSA)], (b) markers of endocrine derangement (serum prolactin, estradiol and progesterone levels), (c) apoptotic changes [serum tumour necrosis factor (TNF)‐α, tissue caspase‐3 activity, percentage of DNA fragmentation and ultrastructural features of apoptosis] and (d) markers of oxidative stress (tissue levels of lipid peroxides and nitric oxide). Carcinoma was absent both in the control and in the NS‐Pro groups. Mammary carcinoma occurred in DMBA and other Pro and Tr groups. The frequency of mammary carcinoma was high in the carcinogen DMBA group (60%), followed by the Tr (56%) and finally the Pro groups (33%). These tumours included papillary, comedo and cribriform carcinomas. As compared with the control group, the development of carcinoma in the carcinogen DMBA group was associated with increased levels of (a) markers of tumorigenicity (77.0 ± 3.3 vs. 209.0 ± 5.6 and P < 0.05 for TSA; 28.7 ± 1.7 vs. 41.8 ± 1.2 and P < 0.01 for LSA), (b) markers of endocrine derangement (2.5 ± 0.1 vs. 3.6 ± 0.3 and P < 0.05 for prolactin; 39.6 ± 1.3 vs. 24.8 ± 2.1 and P < 0.01 for progesterone and 31.0 ± 0.7 vs. 51.1 ± 3.4 and P < 0.01 for estradiol) and (c) markers of oxidative stress (2.3 ± 0.2 vs. 5.2 ± 0.7 and P < 0.01 for lipid peroxides and 4.4 ± 0.2 vs. 7.6 ± 0.8 and P < 0.01 for nitric oxide). Also, it was associated with decreased levels of markers of apoptotic activity (20.8 ± 1.1 vs. 13.4 ± 0.7 and P < 0.01 for caspase‐3; 29.0 ± 1.7 vs. 20.9 ± 1.3 and P < 0.05 for percentage of DNA fragmentation; and 9.4 ± 0.8 vs. 52.1 ± 3.3 and P < 0.01 for TNF‐α). When compared with the carcinogen DMBA group, the development of carcinoma in the Pro and Tr groups was associated with decreased levels of (a) markers of tumorigenicity, (b) markers of endocrine derangement and (c) markers of oxidative stress. Alternatively, carcinogenicity was associated with statistically significant (P < 0.01) increased levels of markers of apoptotic activity. To conclude, the administration of Mel, RA and NS reduced the carcinogenic effects of DMBA, suggesting a protective role. The possible underlying mechanisms of these effects await further investigations.

Evaluation of the impact of laparoscopic ovarian drilling on Doppler indices of ovarian stromal blood flow, serum vascular endothelial growth factor, and insulin-like growth factor-1 in women with polycystic ovary syndrome

OBJECTIVE To study the serum levels and correlation of vascular endothelial growth factor (VEGF), insulin-like growth factor 1 (IGF-1), hormonal profile, and Doppler blood flow changes within the ovarian stroma before and after laparoscopic ovarian drilling (LOD) in women with clomiphene-resistant polycystic ovary syndrome (PCOS). DESIGN Prospective controlled study. SETTING University teaching hospital. PATIENT(S) Twenty-five women with clomiphene-resistant PCOS (group 1) and 20 women with regular menstrual cycles as a comparison group (group 2). INTERVENTION(S) Laparoscopic ovarian drilling. MAIN OUTCOME MEASURE(S) Serum levels of VEGF, IGF-1, and Doppler indices of ovarian stromal blood flow. RESULT(S) The serum levels of VEGF, IGF-1, T, and LH were significantly higher in group 1 before LOD than in group 2. The Doppler indices (pulsatility index and resistance index) of ovarian stromal blood flow were also significantly lower in group 1 before LOD than in group 2. The serum levels of VEGF, T, and LH were significantly reduced in group 1 after LOD compared with in group 1 before LOD. Doppler indices (pulsatility index and resistance index) of ovarian stromal blood flow were significantly increased after LOD. The VEGF levels before LOD were positively correlated with IGF-1, LH, and T. After LOD, the VEGF levels were positively correlated with LH and T. CONCLUSION(S) Higher serum levels of VEGF and IGF-1 may explain the increased vascularity that was demonstrated by Doppler blood flow measurements in PCOS. Laparoscopic ovarian drilling reduced serum VEGF, IGF-1, T, and LH and reduced ovarian blood flow velocities, which may explain the reduction of ovarian hyperstimulation syndrome in women with PCOS after LOD.

Inhibitory effects of melatonin on vascular reactivity: possible role of vasoactive mediators.

Melatonin (MEL), the principal hormone of the vertebral pineal gland, elicits several neurobiological effects. However, the effects of MEL on vascular tissues are still vague. The first goal of this study was to investigate the effect of MEL on isolated rabbit aortic rings and its role in the vascular reactivity to contractile agents, noradrenaline (NA) and phenylephrine (PHE) and relaxant agents (acetylcholine and sodium nitroprusside). In addition, the levels of nitric oxide (NO), cGMP, total calcium, lipid peroxides, superoxide dismutase (SOD) and glutathione (GSH) were also investigated in tissue homogenates of rabbit aortic rings preincubated (20 min) in MEL with and without contractile agents. Our results revealed that MEL has an endothelium-dependent vaso-relaxant effect and potentiated significantly the vaso-relaxant effect of acetylcholine. Moreover, MEL (10(-4) M) had a significant inhibitory effect on the contractile responses of aortic rings to both NA and PHE. In comparison with control tissue rings, the levels of lipid peroxides were significantly increased while the levels of GSH, and SOD activities were significantly decreased in tissue homogenates of aortic rings pre-incubated (20 min) in NA or PHE. In addition, the levels of NO and cGMP were significantly lower in tissue rings pre-treated with NA and PHE, respectively. Also, the levels of total calcium were significantly increased only in tissue rings pre-treated with NA. The levels of lipid peroxides were significantly decreased, while the levels of GSH, NO and cGMP and SOD activities were significantly increased in tissue homogenates of aortic rings incubated (20 min) in MEL (10(-4) M) in comparison to ring tissues incubated in NA or PHE alone. In aortic rings incubated in MEL+PHE, the levels of lipid peroxides were significantly lower while the levels of GSH and cGMP and SOD activities were significantly higher than their levels in ring tissues incubated in PHE. In aortic rings incubated in MEL+NA, the levels of lipid peroxides and total calcium were significantly lower while the levels of NO were significantly higher than their levels in ring tissues incubated in NA alone. We conclude that MEL has an endothelium dependent vasorelaxant effect and potentiates the endothelium dependent vasorelaxation induced by acetylcholine. MEL inhibits the contractile responses of aortic rings to NA and PHE. These effects may be, in part, due to re-balancing the pro-oxidant/antioxidants system, lowered calcium content and elevated NO and cGMP levels in vascular tissue.

Novel B melatonin-loaded chitosan microcapsules: in vitro characterization and antiapoptosis efficacy for aflatoxin B1-induced apoptosis in rat liver

The aim of this study was to prepare buoyant (B) melatonin (MT)-loaded chitosan microcapsules having favourable sustained release characteristics (in simulated gastric fluid (SGF), pH 1.2) in comparison with non-buoyant (NB) chitosan particles. The new buoyant microcapsules were prepared by the ionotropic gelation method using sodium lauryl sulfate (NaLS) for coagulation. The microcapsule characteristics were affected by the initial drug and NaLS concentrations, as well as the presence of sodium dioctyl sulfosuccinate (DOS) or pectin with NaLS in the external phase. In general, spherical microcapsules with 36.90-56.23% encapsulation efficiencies, hollow core and satisfactory release properties were produced. The best sustained release profiles (t(50%): 5h) with near zero-order kinetics were observed with the higher theoretical payload microcapsules prepared with both NaLS and DOS in a 1:2 ratio. In vivo studies were also carried out to exploit the protective effect of the MT-loaded NaLS-DOS microcapsules against aflatoxin B1 (AFB1)-induced toxicity (liver apoptosis) in male rats. The results implied that apoptotic rate was significantly reduced when MT or its microcapsules formulation was co-administered with AFB1. The levels of the oxidative stress indices (malondialdehyde (MDA), a lipid peroxidation product and nitric oxide (NO)) in liver tissues were significantly reduced, while the levels of the hepatic antioxidants (glutathione (GSH) and zinc (Zn), as well as the enzyme activities of glutathione reductase (GR), glutathione peroxidase (GSPx) and glutathione-S-transferase (GST)) which act as antiapoptosis were significantly increased as compared to AFB1 group (without MT). MT microcapsules appeared more effective in reduction of apoptotic rate than free MT as indicated by the decline of caspase-3 activities (an apoptotic marker) and confirmed by histopathology.

Effect of cadmium-polluted water on plasma levels of tumor necrosis factor-α, interleukin-6 and oxidative status biomarkers in rats: Protective effect of curcumin

UNLABELLED The present study was designed to investigate the effect of CdCl₂-polluted drinking water (40 mg CdCl₂/L) on the level of TNF-α and IL-6, as well as oxidative status biomarkers in plasma of rats. The possible protective effect of oral administration of curcumin (50 mg/kg body weight/day) was assessed. Results illustrated that Cd exposure significantly elevated the plasma levels of TNF-α and IL-6 (p<0.001) as compared to normal rats. Also, Cd administration resulted in a significant elevation in the lipid peroxidation and markedly reduction in the activities of SOD and catalase as well as the level of glutathione and total antioxidant capacity in plasma. The co-treatment of Cd with curcumin significantly reduced the levels of TNF-α and IL-6 and ameliorated the alteration in oxidative status biomarkers induced by Cd. Negative correlation between IL-6 or TNF-α was and the plasma activities of catalase, SOD and the level of total antioxidant capacity were found in rats exposed to Cd. CONCLUSION Cadmium toxicity induced the release of TNF-α and IL-6 which is associated with systemic oxidative stress. This may be involved in the mechanism of the Cd toxicity. On the other hand, the findings suggest the curative action of curcumin against Cd toxicity.