Hoda E. Mohamed

Protection against doxorubicin cardiomyopathy in rats: role of phosphodiesterase inhibitors type 4.

Selective cardiotoxicity of doxorubicin (DOX) remains a significant and dose‐limiting clinical problem. The mechanisms implicated are not yet fully defined but may involve the production of reactive oxygen species or expression of cytokines. Although patients with advanced congestive heart failure express elevated circulating levels of tumour necrosis factor‐α (TNFα), little is known about the prognostic importance and regulation of TNFα in the heart in cardiac disease states. Here we tested whether the expression of TNFα, along with oxidative stress, is associated with the development of DOX‐induced cardiomyopathy (DOX‐CM) and whether concurrent treatment with taurine (Taur), an antioxidant, or rolipram (Rolp), a TNFα inhibitor, offer a certain protection against DOX cardiotoxic properties. DOX (cumulative dose, 12 mg kg−1) was administered to rats in six equal (intraperitoneal) injections over a period of 6 weeks. Cardiomyopathy was evident by myocardial cell damage, which was characterized by a dense indented nucleus with peripheral heterochromatin condensation and distorted mitochondria, as well as significant increase in serum levels of creatine kinase and lactate dehydrogenase. DOX also induced an increment (P < 0.001) in serum TNFα and plasma nitric oxide levels. The extent of left ventricular (LV) superoxide anion, lipid peroxide measured as malondialdehyde, catalase and calcium content were markedly elevated, whereas superoxide dismutase, total and non‐protein‐bound thiol were dramatically decreased in DOX‐treated rats. Exaggeration of DOX‐CM was achieved by intraperitoneal injection of lipopolysaccharide (LPS) (1 mg kg−1) 18h before sampling and evaluated by highly significant increase in heart enzymes (P < 0.001), oxidative stress biomarkers and TNFα production. Pre‐ and co‐treatment of DOX or DOX‐LPS rats with Taur (1% daily supplemented in drinking water, 10 days before and concurrent with DOX) or Rolp (3 mg kg−1, intraperitoneally, one dose before DOX administration then every 2 weeks throughout the experimental period) ameliorated the deleterious effect of both DOX and LPS on the aforementioned parameters. Meanwhile, it is noteworthy that Rolp exhibited a more preferable effect on serum TNFα level. Taur and rolipram also restored the myocardial apoptosis induced by DOX. In conclusion, a cumulative dose of DOX affected free radical and TNFα production in the heart of an experimental cardiomyopathy animal model. The current results suggest that down‐regulation of these radicals and cytokines could be maintained by using the free radical scavenger Taur or, more favourably, the TNFα inhibitor Rolp.

Hyperhomocysteinaemia and cardiovascular risk in female ovariectomized rats: role of folic acid and hormone replacement therapy

Hyperhomocysteinaemia is an independent risk factor for arteriosclerosis, recurrent thromboembolic complications and osteoporosis. After menopause, a high level of total homocysteine seems to be secondary to the altered hormonal status. Hormone replacement therapy (HRT) limits the development of coronary artery disease through a variety of mechanisms. One such mechanism is through affecting homocysteine metabolism. Folate and vitamin B12 deficiencies are considered to be major risks for hyperhomocysteinaemia. This study, therefore, was undertaken to examine whether lowering homocysteine with HRT or folic acid in ovariectomized rats could attenuate cardiovascular complications. Sixty sexually mature female Wistar rats were ovariectomized. Three weeks later, they were treated with estradiol (15 μg kg−1 every two weeks, i.m.) or folic acid (90 μg daily, orally), either alone or in a combined form for four weeks. In addition, groups of ovariectomized rats (positive control) and healthy rats (negative control) were given cottonseed oil. Blood samples were then collected for serum and plasma separation. Serum total homocysteine, folate, estradiol, plasma nitric oxide (NO), lipid profile, and susceptibility of non‐high‐density‐lipoprotein cholesterol (non HDLC) contentto oxidation were determined. In ovariectomized rats, hyperhomocysteinaemia was established and associated with significant increments of both atherogenic indexes (total cholesterol/HDLC, low‐density‐lipoprotein cholesterol (LDLC)/HDLC) and susceptibility of their non HDLC to oxidation. However, plasma NO, serum folate, and estradiol levels significantly decreased. HRT and folic acid significantly reduced total homocysteine and susceptibility of non HDLC to oxidation and increased plasma NO content. Moreover, a significant negative correlation was found between total homocysteine versus folate and estradiol (r = − 0.5, P< 0.01; r = − 0.25, P< 0.05, respectively). Meanwhile, a positive correlation with the susceptibility of lipoprotein to oxidation was observed (r = 0.85, P< 0.001). In conclusion, a low folate level is found to be associated with elevated total homocysteine. Folic acid supplementation, either individually or in a combined form with HRT, has a beneficial effect in low estrogen status subsequent to ovariectomy.

Effect of erythropoietin therapy on the progression of cisplatin induced renal injury in rats

Cisplatin is one of the most important chemotherapeutic agents useful in the treatment of a variety of solid tumors; however, it has several side effects such as nephrotoxicity. In the present study, the effect of rhEPO on acute kidney injury induced by i.p. injection of rats with 9.0 mg/kg cisplatin was studied. It was observed that EPO treated group showed a significantly lower rate in the extent and severity of the histological signs of kidney injury than untreated one. This is attributed to (i) a decrease in the elevated oxidative and nitrosative stress markers, (ii) reduction of the expression of VEGF, HO-1 and iNOS as well as (iii) improvement of Bcl2 immunoreaction in most tubular cells. Thus, EPO may be one of the futures therapeutic possibilities to overcome the side effects of anti-cancer drugs induced acute renal injury through various mechanisms including down regulation of vascular endothelial growth factor (VEGF), hemeoxygenase-1 (HO-1) and inducible nitric oxide synthase (iNOS) expressions in addition to stimulation of tubular cell regeneration.

Biochemical effect of a ketogenic diet on the brains of obese adult rats

Excess weight, particularly abdominal obesity, can cause or exacerbate cardiovascular and metabolic disease. Obesity is also a proven risk factor for Alzheimers disease (AD). Various studies have demonstrated the beneficial effects of a ketogenic diet (KD) in weight reduction and in modifying the disease activity of neurodegenerative disorders, including AD. Therefore, in this study we examined the metabolic and neurodegenerative changes associated with obesity and the possible neuroprotective effects of a KD in obese adult rats. Compared with obese rats fed a control diet, obese rats fed a KD showed significant weight loss, improvement in lipid profiles and insulin resistance, and upregulation of adiponectin mRNA expression in adipose tissue. In addition, the KD triggered significant downregulation of brain amyloid protein precursor, apolipoprotein E and caspase-3 mRNA expression, and improvement of brain oxidative stress responses. These findings suggest that a KD has anti-obesity and neuroprotective effects.

Pioglitazone Attenuates Cardiac Fibrosis and Hypertrophy in a Rat Model of Diabetic Nephropathy

Pioglitazone has been demonstrated to have beneficial effects on cardiovascular outcomes. However, little is known about its effect on cardiac remodeling associated with diabetic nephropathy. Therefore, this study was designed to study the effects of pioglitazone on cardiac fibrosis and hypertrophy in a rat model of diabetic nephropathy. For this purpose, male Wistar albino rats were randomly assigned into 4 groups (n = 10 per group): normal (N) group, diabetic (D) group, diabetic nephropathic (DN) group received an equal amount of vehicle (0.5% carboxy methyl cellulose), and diabetic nephropathic group treated by oral administration of pioglitazone (10 mg/kg per d) for 4 weeks. Diabetic nephropathy was induced by subtotal nephrectomy plus streptozotocin (STZ) injection. The results revealed that DN rats showed excessive deposition of collagen fibers in their cardiac tissue, along with a marked myocyte hypertrophy. This was associated with a dramatic upregulation of cardiac transforming growth factor-β1 (TGF-β1) gene. Furthermore, the gene expression of matrix metalloproteinase 2 (MMP-2) decreased, while the gene expression of tissue inhibitor of metalloproteinase 2 (TIMP-2) increased in the hearts of DN rats. In addition, enhanced lipid peroxidation and myocardial injury, evidenced by a significant increase in their serum creatine kinase-MB level were observed in DN rats. All these abnormalities were ameliorated by pioglitazone administration. Our findings suggest that upregulation of cardiac TGF-β1 gene along with the imbalance between MMP-2 and TIMP-2 expressions is critically involved in cardiac fibrosis associated with diabetic nephropathy. Pioglitazone can ameliorate cardiac remodeling by suppressing the gene expression of TGF-β1 and regulating the MMP-2/TIMP-2 system.

Bone marrow-derived mesenchymal stem cells effectively regenerate fibrotic liver in bile duct ligation rat model

Mesenchymal stem cells (MSCs) have attracted lots of attention for the treatment of acute liver failure and end-stage liver diseases. This study aimed at investigating the fundamental mechanism by which bone marrow-derived MSCs (BM-MSCs) induce liver regeneration of fibrotic liver in rats. Rats underwent bile duct ligation (BDL) surgery and four weeks later they were treated with either BM-MSCs (3 × 106 cells /rat, once, tail vein injection) or silymarin (100 mg/kg, daily, orally) for four weeks. Liver function tests and hepatic oxidative stress were determined. Hepatic injury and fibrosis were assessed by H and E, Sirus red staining and immunohistochemical expression of α-smooth muscle actin (α-SMA). Hepatocyte growth factor (HGF) and the gene expression of cytokeratin-19 (CK-19) and matrix metalloproteinase-2 (MMP-2) in liver tissue were determined. BDL induced cholestatic liver injury characterized by elevated ALT and AST activities, bilirubin and decreased albumin. The architecture damage was staged as Metavir score: F3, A3. Fibrosis increased around proliferating bile duct as indicated by sirus red staining and α-SMA immunostaining. Fibrogenesis was favored over fibrolysis and confirmed by decreased HGF with increased expression of CK-19, but decreased MMP-2 expression. BM-MSCs treatment restored deteriorated liver functions and restored the histological changes, resolved fibrosis by improving liver regenerative capabilities (P < 0.001), increases in HGF and MMP-2 mRNA and downregulating CK-19 mRNA. Sliymarin, however, induced similar but less prominent effects compared to BM-MSCs. In conclusion, liver regenerative capabilities can be stimulated by BM-MSCs via augmentation of HGF that subsequently up-regulate MMP-2 mRNA while downregulating CK-19 mRNA.

Nicotine and vascular endothelial dysfunction in female ovariectomized rats: role of estrogen replacement therapy.

Objectives  The protective effects of estrogen replacement therapy (ERT) against oxidative injury and endothelial dysfunction in the aortic tissues induced with nicotine in ovariectomized (OVX) rats were investigated.

Bladder function in mice with inducible smooth muscle-specific deletion of the manganese superoxide dismutase gene

Manganese superoxide dismutase (MnSOD) is considered a critical component of the antioxidant systems that protect against oxidative damage. We are interested in the role of oxidative stress in bladder detrusor smooth muscle (SM) in different disease states. In this study, we generated an inducible, SM-specific Sod2(-/-) mouse model to investigate the effects of MnSOD depletion on the function of the bladder. We crossbred floxed Sod2 (Sod2(lox/lox)) mice with mice containing heterozygous knock-in of a gene encoding a tamoxifen-activated Cre recombinase in the SM22α promoter locus [SM-CreER(T2)(ki)(Cre/+)]. We obtained Sod2(lox/lox),SM-CreER(T2)(ki)(Cre/+) mice and injected 8-wk-old males with 4-hydroxytamoxifen to induce Cre-mediated excision of the floxed Sod2 allele. Twelve weeks later, SM-specific deletion of Sod2 and depletion of MnSOD were confirmed by polymerase chain reaction, immunoblotting, and immunohistochemistry. SM-specific Sod2(-/-) mice exhibited normal growth with no gross abnormalities. A significant increase in nitrotyrosine concentration was found in bladder SM tissue of SM-specific Sod2(-/-) mice compared with both wild-type mice and Sod2(+/+), SM-CreER(T2)(ki)(Cre/+) mice treated with 4-hydroxytamoxifen. Assessment of 24-h micturition in SM-specific Sod2(-/-) mice revealed significantly higher voiding frequency compared with both wild-type and SM-specific Cre controls. Conscious cystometry revealed significantly shorter intercontraction intervals and lower functional bladder capacity in SM-specific Sod2(-/-) mice compared with wild-type mice. This novel model can be used for exploring the mechanistic role of oxidative stress in organs rich in SM in different pathological conditions.

Beneficial effects of pioglitazone against cardiovascular injury are enhanced by combination with aliskiren in a rat model of diabetic nephropathy

Objectives  Aliskiren is the first in a new class of orally active direct renin inhibitors, approved for the treatment of hypertension. However, the efficacy of aliskiren in diabetic cardiovascular complications remains to be defined. This study aimed to test the hypothesis that aliskiren may enhance the beneficial effects of pioglitazone against cardiovascular injury associated with diabetic nephropathy.

Obesity and neurodegeneration: effect of a Mediterranean dietary pattern

Abstract Obesity is a serious global health problem and is associated with a variety of chronic diseases. Increasing evidence suggests that obesity increases the risk of Alzheimers disease. Several studies have shown that a Mediterranean diet is effective in reducing weight and epidemiological data suggest that such a diet is associated with lower risk of neurodegenerative disorders, including Alzheimers disease. Therefore, we examined the relationship between obesity and neurodegeneration and the possible effects of Mediterranean diet on both in adult obese rats. Obese rats showed significant dyslipidaemia, insulin resistance, down-regulation of adiponectin mRNA expression in adipose tissue, up-regulation of brain amyloid precursor protein, apolipoprotein E and caspase-3 mRNA expression and a marked increase in brain oxidative stress. Treatment with Mediterranean diet induced significant weight loss and improvement in these various markers. The present study suggests that Mediterranean diet is a viable nutritional intervention in obesity and, more importantly, in the prevention and treatment of Alzheimers disease.