Amira A. Shaheen

Effect of dietary zinc on lipid peroxidation, glutathione, protein thiols levels and superoxide dismutase activity in rat tissues

Dietary zinc deficiency can cause increased lipid peroxidation while zinc supplementation inhibited this process. The aim of this study was to investigate the effect of dietary zinc on malondialdehyde (MDA) product as an index of endogenous lipid peroxidation, glutathione (GSH) and protein thiols (PrSHs) as well as superoxide dismutase (SOD) activity in rat blood, liver and pancreas. Young male rats were fed a zinc deficient (ZD) basal diet containing congruent to 0.5 ppm zinc or were fed ad libitum (AL) a zinc adequate diet (30 ppm zinc) for 3 weeks. The ZD rats were then fed the basal diet supplemented with either 100 ppm zinc or 1000 ppm zinc for another 3 weeks. The zinc concentration of the investigated tissues reflected the dietary zinc content. Plasma, liver and pancreas MDA measurements from ZD rats revealed significant increases (P < 0.05, < 0.001) as compared to AL control values, the highest increase was in pancreas. ZD rats also displayed significant decreases in their blood and liver GSH content (P < 0.001, < 0.05) and SOD activity (P < 0.001) as well as serum PrSHs (P < 0.001) as compared to AL control values. However, these measurements in pancreas were insignificantly changed except GSH content was significantly increased (P < 0.05). Feeding ZD rats a diet containing 100 ppm or 1000 ppm zinc resulted in a significant reduction of the endogenous MDA formation (P < 0.05, < 0.001) in their tissues with the reversal of changes in the other parameters, so that their levels were nearly restored to AL control values especially in response to 1000 ppm zinc.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of various stressors on the level of lipid peroxide, antioxidants and Na +, K+-ATPase activity in rat brain

The level of malondialdehyde (MDA), an index of lipid peroxidation, and the antioxidants superoxide dismutase (SOD) and glutathione (GSH), as well as the activity of Na+, K+-ATPase, were assessed in whole rat brain after immobilization, anemic hypoxia (NaNO2) and 72 h starvation. The effect of these stressors on plasma glucose and corticosterone levels was also observed. Hypoxia and starvation stimulated the lipidj peroxide formation in braini as indicated by an increase in the level of MDA, being higher after starvation than hypoxia. Brain SOD activity was also increased in response to hypoxia and starvation while GSH content was only diminished ini hypoxia. However, neither MDA nor antioxidants were affected by immobilization. On the other hand, the activity of brain Na+, K+-ATPase was significantly increased by immobilization and hypoxia but decreased in starvation. A similar pattern of change was also observed in plasma glucose and corticosterone levels in response to these stressors. These results elucidate differences in the biochemical response of animals towards various types of stress, with increased lipid peroxide formation in hypoxia and starvation.

Effect of pretreatment with vitamin E or diazepam on brain metabolism of stressed rats

The effect of vitamin E (VE) or diazepam (DZ) pretreatment on some carbohydrate metabolic aspects in the brains of stressed rats was studied. DZ and VE were given i.p. at doses of 5 mg/kg body wt for 6 days prior to subjecting the animals to single swimming stress (SSS). Pretreatment of the rats with DZ or VE diminished the stress-induced increases in plasma corticosterone and glucose levels and reversed the decrease due to stress on brain ATP, glucose, glycogen and pyruvate contents. The increase in brain ADP and lactate was brought back to levels which approached the pre-stressed values. Moreover, DZ and VE pretreatments helped in attenuating the stress-induced alteration in brain mitochondrial and cytosolic hexokinase as well as sodium, potassium adenosine triphosphatase (Na+,K(+)-ATPase) activities. The change in these metabolic parameters produced by VE pre-treatment was less than that exhibited by DZ. The effects of VE were explained in light of its antioxidant property in preventing the free radical production and lipid peroxide formation which are important factors in the pathogenesis of stress.

Effect of vitamin C administration in modulating some biochemical changes in arthritic rats

Two phases of arthritis, acute phase (four days after adjuvant inoculation) and chronic phase (21 or 29 days after adjuvant inoculation) were studied in male rats. The effect of administration of vitamin C in a daily oral dose of 50 mg/kg body wt for four and 21 days starting on the day of adjuvant inoculation and for 7 days starting 21 days after adjuvant inoculation against these phases of arthritis was demonstrated. Results showed that prolonged administration of vitamin C (21 days) increased the lowered serum sulphydryl (SH-groups) to prearthritic values while it decreased the elevated level of blood glutathione (GSH) of arthritic rats. However, neither (four-day) nor seven-day treatment with vitamin C exerted any significant changes in these parameters. The results showed also a slight significant increase in the level of erythrocyte superoxide dismutase activity (SOD) [1.15.1.1] upon seven-day treatment with vitamin C. Meanwhile, four-, 21- or seven-day treatment with vitamin C produced no significant change in the elevated levels of serum ceruloplasmin (Cp) and alpha 2-macroglobulin (alpha 2-M) of arthritic rats. However, 21-day and 7-day administration of vitamin C has improved the lowered A/G ratio in these animals. The improvement in these parameters after prolonged administration of vitamin C was explained in the light of the antioxidant property of this vitamin and suggests a beneficial role for it in the treatment of arthritis.

Modulation of age-related changes in oxidative stress markers and energy status in the rat heart and hippocampus: a significant role for ozone therapy.

Oxidative stress emerges as a key player in the ageing process. Controlled ozone administration is known to promote an oxidative preconditioning or adaptation to oxidative stress. The present study investigated whether prophylactic ozone administration could interfere with the age‐related changes in the heart and the hippocampus of rats. Four groups of rats, aged about 3 months old, were used. Group 1 (Prophylactic ozone group) received ozone/oxygen mixture by rectal insufflations (0.6 mg/kg) twice/week for the first 3 months, then once/week till the age of 15 months. Group 2 (Oxygen group) received oxygen as vehicle for ozone in a manner similar to group 1. Group 3 (Aged control group) was kept without any treatment until the age of 15 months. A fourth group of rats (Adult control group) was evaluated at 3 months of age to provide baseline data. Ozone alleviated age‐associated redox state imbalance as evidenced by reduction of lipid and protein oxidation markers, lessening of lipofuscin deposition, restoration of glutathione levels in both tissues and normalization of glutathione peroxidase activity in the heart tissue. Ozone also mitigated age‐associated energy failure in the heart and the hippocampus, improved cardiac cytosolic Ca2+ homeostasis and restored the attenuated Na+, K+‐ATPase activity in the hippocampus of aged rats. These data provide new evidence concerning the anti‐ageing potential of prophylactic ozone administration. Copyright

Effect of praziquantel on some aspects of carbohydrate metabolism in mice infected with Schistosoma mansoni

Schistosoma mansoni infection in mice resulted in a marked decrease in blood glucose and liver glycogen accompanied by a significant increase in hepatic glucose-6-phosphatase (G-6-Pase) activity. Moreover, the results indicated that infection produced a significant increase in blood pyruvate and hepatic glucose-6-phosphate dehydrogenase (G-6-PD) activity with a significant decrease in blood lactate. Infected mice were treated with praziquantel which was given at two doses of 500 mg/kg body wt on two consecutive days. Seven and 14 days respectively after drug administration, such treatment caused a marked improvement in the previous aspects of carbohydrate metabolism. This is indicated by the tendency of the blood glucose of infected mice to be restored, the marked increase in their liver glycogen content, the normalization of their blood lactate and pyruvate as well as by the marked decrease of their hepatic G-6-Pase activity and the progressive increase in their hepatic G-6-PD activity. Praziquantel given to normal mice moderately affected the blood glucose and the previously mentioned hepatic enzymes. However, the drug markedly increased the liver glycogen content of normal mice and failed to elicit any change in their blood pyruvate and lactate. Possible explanations of these findings are discussed.

Pretreatment with turmeric modulates the inhibitory influence of cisplatin and paclitaxel on CYP2E1 and CYP3A1/2 in isolated rat hepatic microsomes

Previous animal studies have shown that turmeric can significantly modulate the activity of several drug metabolizing enzymes, this may dramatically affect the bioavailability of several drugs resulting in over dose or less therapeutic effects. This study was directed to evaluate the inhibitory effects of cisplatin and paclitaxel on two CYP450 enzymes namely CYP2E1 and CYP3A1/2 in hepatic microsomes isolated from normal and turmeric pretreated rats. Cisplatin and paclitaxel were added by different concentrations to hepatic microsomes isolated from untreated and turmeric (100 mg/kg/day) pretreated rats for 15 days after receiving pyrazole or dexamethasone for induction of CYP2E1 and CYP3A1/2 respectively. The kinetic potency of these drugs as CYP inhibitors was determined by analysis of Lineweaver-Burk plot. Addition of cisplatin or paclitaxel by (10, 50 and 100 μM) to hepatic microsomes from normal or turmeric pretreated rats caused a concentration dependent inhibition of CYP2E1, with an evidence of less inhibition in turmeric pretreated microsomes particularly at higher concentration. Both drugs at 100 μM displayed a mixed type of inhibition of CYP2E1 in normal or turmeric pretreated microsomes where paclitaxel was the most potent inhibitor. Cisplatin (10, 50 and 100 μM) caused a concentration dependant inhibition of CYP3A1/2 that was enhanced by turmeric pretreatment. The inhibition of CYP3A1/2 by cisplatin (100 μM) was in non-competitive manner with a smaller Ki value in turmeric pretreated microsomes. The inhibitory influence of paclitaxel (10, 50 and 100 μM) on CYP3A1/2 decreased with increasing the drug concentration and this inhibition was augmented by turmeric pretreatment. Interestingly, the inhibition of this enzyme by paclitaxel (10 μM) was switched from mixed type in normal microsomes to competitive manner in turmeric pretreated ones with a marked reduction of Ki values reflecting greater inhibitory influence of paclitaxel on CYP3A1/2 by turmeric pretreatment. In conclusion, turmeric pretreatment attenuated the inhibitory influence of cisplatin and paclitaxel on CYP2E1 activity and magnified their inhibition on CYP3A1/2, thus the use of turmeric with drugs or other medications should raise concern for drugs-herb interactions.

Ozone ameliorates age-related oxidative stress changes in rat liver and kidney: Effects of pre- and post-ageing administration

The ageing process is known to be accompanied by increased oxidative stress and compromised antioxidant defenses. Controlled ozone administration has been shown to be effective in various pathophysiological conditions with an underlying oxidative burden. However, its effect on the biochemical alterations associated with the ageing process has been rarely studied. Therefore, the present work was carried out to study the role of ozone in counteracting the state of oxidative stress associated with ageing in rat liver and kidneys using two experimental models. In the pre-ageing model, ozone was administered prior to the onset of ageing at adulthood and continued after the start of the ageing process (3-month-old rats until the age of 15 months). While in the post-ageing model, ozone was administered after ageing has begun and lasted for one month (14-month-old rats until the age of 15 months). The pre-ageing ozone administration effectively reduced lipid and protein oxidation markers, namely, malondialdehyde and protein carbonyl levels and decreased lipofuscin pigment deposition in rat liver and kidneys. Moreover, it significantly restored hepatic and renal reduced glutathione (GSH) contents and normalized cytosolic hepatic glutathione peroxidase activity. Similar but less pronounced effects were observed in the post-ageing ozone-treated group. Nevertheless, in the latter model ozone administration failed to significantly affect liver and kidney lipofuscin levels, as well as kidney GSH contents. These data provide evidences for potentially positive effects of pre-ageing ozone therapy in neutralizing chronic oxidative stress associated with ageing in rat liver and kidneys.

Impact of Genetic Polymorphism of methylenetetrahydrofolate reductase C677T on Development of Hyperhomocysteinemia and Related Oxidative Changes in Egyptian β-Thalassemia Major Patients

Background β-thalasemia major (β-TM) patients often suffer from various vascular complications together with increased oxidative stress. Hyperhomocysteinemia (Hhcy) has been defined as a risk factor for these complications. Genetic polymorphism of methylenetetrahydrofolate reductase (MTHFR) C677T has been shown to cause Hhcy particularly in individuals with low B-vitamins. However, the status of homocysteine (hcy) in β-TM has not yet been adequately defined. Aim To evaluate the genetic polymorphism of MTHFR C677T among β-TM patients and its prospective contribution to Hhcy and related oxidative changes. Subjects and Methods Genotyping for MTHFR C677T was done by PCR-RFLP technique. Plasma hcy, vitamin B12, folate, malondialdehyde (MDA), total antioxidant capacity (TAC), oxidized low density lipoprotein (oxLDL), total nitric oxide (NOx) and lipid profile were determined in 66 β-TM patients and 66 control subjects of matched age and sex. Results The prevalence of MTHFR 677TT genotype was significant among β-TM patients (12%) compared to (3%) controls (OR = 4.9, 95%CI:1.2–24.2,P = 0.03). A strong association between Hhcy and MTHFR TT genotype was observed (OR = 7.7, 95%CI:2.8–20.9) where all β-TM patients with TT genotype were hyperhomocystienemic (≥ 15 μmol/l) and having sub-optimal folate level than those with CT or CC genotypes. Hyperhomocystienemic patients have suffered from increased oxidative stress characterized by significant increase in plasma MDA and oxLDL, and a significant reduction of plasma TAC and total NOx. Lipid profile of those patients was severely affected indicated by reduction in HDL and HDL/LDL and elevation in atherogenic index as compared with CC genotype. Other measured parameters were not significantly different among β-TM patients with different MTHFR genotypes. Conclusion This study suggests that Egyptian β-TM patients with MTHFR 677TT genotype could be at increasing risk of developing Hhcy particularly with folate deficiency. This state of Hhcy may account potentially for most oxidative changes and atherogenic vascular complications frequently reported in β-TM patients.

Avemar and Echinacea extracts enhance mobilization and homing of CD34(+) stem cells in rats with acute myocardial infarction.

IntroductionActivation of endogenous stem cell mobilization can contribute to myocardial regeneration after ischemic injury. This study aimed to evaluate the possible role of Avemar or Echinacea extracts in inducing mobilization and homing of CD34+ stem cells in relation to the inflammatory and hematopoietic cytokines in rats suffering from acute myocardial infarction (AMI).MethodsAMI was developed by two consecutive subcutaneous injections of isoprenaline (85 mg/kg). AMI rats were either post-treated or pre- and post-treated daily with oral doses of Avemar (121 mg/kg) or Echinacea (130 mg/kg). In whole blood, the number of CD34+ cells was measured by flow cytometry and their homing to the myocardium was immunohistochemically assessed. Serum creatine kinase, vascular endothelial growth factor, interleukin-8 and granulocyte macrophage colony stimulating factor were determined on days 1, 7 and 14 after AMI. Sections of the myocardium were histopathologically assessed.ResultsRats pre- and post-treated with Avemar or Echinacea exhibited substantial increases in the number of circulating CD34+ cells, peaking on the first day after AMI to approximately 13-fold and 15-fold, respectively, with a decline in their level on day 7 followed by a significant increase on day 14 compared to their corresponding AMI levels. Only post-treatment with Echinacea caused a time-dependent increase in circulating CD34+ cells on days 7 and 14. Such increases in circulating CD34+ cells were accompanied by increased homing to myocardial tissue 14 days after AMI. Interestingly, pre- and post-treatment with Avemar or Echinacea substantially increased serum creatine kinase on day 1, normalized its activity on day 7 and, on continued treatment, only Echinacea markedly increased its activity on day 14 compared to the corresponding AMI values. Moreover, both treatments modified differently the elevated serum vascular endothelial growth factor and the lowered granulocyte macrophage colony stimulating factor levels of the AMI group but did not affect the level of interleukin-8. These results were supported histopathologically by reduced inflammatory reactions and enhanced neovascularization.ConclusionAvemar and Echinacea extracts can effectively induce mobilization and homing of CD34+ stem cells to the myocardial tissue and thus may help in stem cell-based regeneration of the infarcted myocardium.