Ashraf K. Bahgat

Ginkgo biloba extract (EGb 761) normalizes hypertension in 2K, 1C hypertensive rats: role of antioxidant mechanisms, ACE inhibiting activity and improvement of endothelial dysfunction.

The 2 kidney, 1-clip (2K, 1C) model of hypertension was used to investigate the potential antihypertensive effect of a standardized leaf extract of Ginkgo biloba (EGb 761). Clipping of the renal artery resulted in gradual elevation of the systolic blood pressure (SBP) reaching a plateau after 4 weeks of surgery. Treatment of hypertensive rats with EGb 761 (60, 90, 180 mg/kg/day orally) was therefore started 4 weeks after surgery and continued for 3 weeks. This led to a dose-dependent reduction in SBP with no significant change in heart rate. Control hypertensive rats showed a significant elevation of total protein thiols (Pr-SHs level) in both clipped and non-clipped kidneys as well as in the serum. However, glutathione peroxidase (GSH-Px) activity was decreased in the clipped kidneys but elevated in the non-clipped ones and in the blood. The malondialdehyde (MDA) level was raised in clipped kidneys but not in non-clipped ones nor in the serum. Nitric oxide (NO level) and angiotensin converting enzyme (ACE) activity were increased in both clipped and non-clipped kidneys but not in the serum. Endothelium-dependent and -independent relaxation of aortic rings towards acetylcholine (Ach) and sodium nitroprusside (SNP) were impaired. Treatment with EGb 761 (180 mg/kg/day for 3 weeks) was associated with recovery of GSH-Px activity in clipped kidneys, inhibition of ACE activity in both kidneys and a reduction in the elevated NO level of the non-clipped kidneys, decreased responsiveness to the vasoconstrictor NE and improvement of endothelial function as evidenced by restoration of endothelium-dependent vasorelaxation induced by Ach. The observed beneficial effects of the EGb 761 may be attributed to different factors, including ACE inhibition and maintenance of cellular antioxidant capacity as well as preserving vascular reactivity towards endothelium-dependent and -independent vasodilators while inhibiting responses to vasoconstrictors.

Solanum indicum ssp. distichum extract is effective against l‐NAME‐induced hypertension in rats

Solanum indicum ssp. distichum is used as a vegetable in some parts of Africa and claimed in folk medicine to guard against cardiovascular disorders. It was of interest to study the potential blood pressure lowering effects of a standardized extract of the fruit. An ethanolic extract of the fruit, standardized to contain > 0.15% chlorogenic acids, was tested orally in both normotensive rats and in those rendered hypertensive by twice daily intraperitoneal injection of NW‐nitro‐l‐arginine methylester (l‐NAME) for 1 week. The extract was either given at the same time as l‐NAME or after the establishment of hypertension. The systolic blood pressure (SBP) was measured non‐invasively using a tail cuff computer‐aided monitoring device. Treatment of normotensive rats with the extract (30–300 mg/kg) for 4 weeks showed no hypotensive effect. Giving the extract (100 and 300 mg/kg) orally once daily during the 1 week hypertension induction period with l‐NAME prevented the development of hypertension. Administration of the extract orally for 1 week after the establishment of hypertension tended to normalize the blood pressure. Pharmacological evidence for the antihypertensive activity of S. distichum is hereby reported for the first time. The extract showed good prophylactic as well as curative effect against l‐NAME‐induced hypertension, whereby its content of chlorogenic acids may play a minor role. Other constituents may be responsible for the antihypertensive action. The findings support further development of the extract as a potential therapeutically useful antihypertensive agent.

Resveratrol and fenofibrate ameliorate fructose-induced nonalcoholic steatohepatitis by modulation of genes expression

AIM To evaluate the effect of resveratrol, alone and in combination with fenofibrate, on fructose-induced metabolic genes abnormalities in rats. METHODS Giving a fructose-enriched diet (FED) to rats for 12 wk was used as a model for inducing hepatic dyslipidemia and insulin resistance. Adult male albino rats (150-200 g) were divided into a control group and a FED group which was subdivided into 4 groups, a control FED, fenofibrate (FENO) (100 mg/kg), resveratrol (RES) (70 mg/kg) and combined treatment (FENO + RES) (half the doses). All treatments were given orally from the 9(th) week till the end of experimental period. Body weight, oral glucose tolerance test (OGTT), liver index, glucose, insulin, insulin resistance (HOMA), serum and liver triglycerides (TGs), oxidative stress (liver MDA, GSH and SOD), serum AST, ALT, AST/ALT ratio and tumor necrosis factor-α (TNF-α) were measured. Additionally, hepatic gene expression of suppressor of cytokine signaling-3 (SOCS-3), sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), malonyl CoA decarboxylase (MCD), transforming growth factor-β1 (TGF-β1) and adipose tissue genes expression of leptin and adiponectin were investigated. Liver sections were taken for histopathological examination and steatosis area were determined. RESULTS Rats fed FED showed damaged liver, impairment of glucose tolerance, insulin resistance, oxidative stress and dyslipidemia. As for gene expression, there was a change in favor of dyslipidemia and nonalcoholic steatohepatitis (NASH) development. All treatment regimens showed some benefit in reversing the described deviations. Fructose caused deterioration in hepatic gene expression of SOCS-3, SREBP-1c, FAS, MDA and TGF-β1 and in adipose tissue gene expression of leptin and adiponectin. Fructose showed also an increase in body weight, insulin resistance (OGTT, HOMA), serum and liver TGs, hepatic MDA, serum AST, AST/ALT ratio and TNF-α compared to control. All treatments improved SOCS-3, FAS, MCD, TGF-β1 and leptin genes expression while only RES and FENO + RES groups showed an improvement in SREBP-1c expression. Adiponectin gene expression was improved only by RES. A decrease in body weight, HOMA, liver TGs, AST/ALT ratio and TNF-α were observed in all treatment groups. Liver index was increased in FENO and FENO + RES groups. Serum TGs was improved only by FENO treatment. Liver MDA was improved by RES and FENO + RES treatments. FENO + RES group showed an increase in liver GSH content. CONCLUSION When resveratrol was given with half the dose of fenofibrate it improved NASH-related fructose-induced disturbances in gene expression similar to a full dose of fenofibrate.

Effects of combined PPAR-γ and PPAR-α agonist therapy on fructose induced NASH in rats: Modulation of gene expression

Peroxisome proliferator-activated receptors (PPARs) gamma and alpha have been shown to play key roles in maintaining glucose and lipid homeostasis by acting as insulin sensitizers and lipid-lowering agents respectively, which would make them potential candidates for the treatment of non-alcoholic steatohepatitis (NASH) characterized by insulin resistance, hyperglycemia, and hypertriglyceridemia. The effects of pioglitazone, a PPAR-γ agonist, and fenofibrate, a PPAR-α agonist, as monotherapy and in combination on the expressions of key genes linked to the development of NASH were studied in rats with fructose-induced NASH. Fructose-enriched diet was given to rats for 12 weeks. Fenofibrate (100mg/kg), pioglitazone (4 mg/kg) and combined treatment with both in half doses were given. Body weight, liver index, insulin resistance indices, triglycerides, oxidative stress markers, AST/ALT ratio and TNF-α were measured. Additionally, hepatic genes expressions of SOCS-3, sterol regulatory element binding protein-1c, fatty acid synthase, malonyl CoA decarboxylase, TGF-β1, and adipose tissue genes expressions of leptin and adiponectin were investigated. The combination of both drugs, in half doses, improved NASH-related disturbances similar to, or even better than, a full dose of fenofibrate alone possibly due to attenuating effects of pioglitazone on expression of genes responsible for insulin resistance, fatty acid synthesis and fibrosis in addition to correcting the balance between leptin and adiponectin. Histopathology confirmed the ability of this combination to decrease steatosis area and to normalize hepatic tissue structure. In Conclusion, dual activation of PPAR-γ and PPAR-α has remarkable effect in ameliorating NASH by modulation of some hepatic and adipose tissue genes expressions.

Galantamine anti-colitic effect: Role of alpha-7 nicotinic acetylcholine receptor in modulating Jak/STAT3, NF-κB/HMGB1/RAGE and p -AKT/Bcl-2 pathways

Vagal stimulation controls systemic inflammation and modulates the immune response in different inflammatory conditions, including inflammatory bowel diseases (IBD). The released acetylcholine binds to alpha-7 nicotinic acetylcholine receptor (α7 nAChR) to suppress pro-inflammatory cytokines. This provides a new range of potential therapeutic approaches for controlling inflammatory responses. The present study aimed to assess whether galantamine (Galan) anti-inflammatory action involves α7 nAChR in a 2,4,6-trinitrobenzene sulfonic acid (TNBS) model of colitis and to estimate its possible molecular pathways. Rats were assigned into normal, TNBS, sulfasalazine (Sulfz), Galan treated (10 mg/kg), methyllycaconitine (MLA; 5.6 mg/kg), and MLA + Galan groups. Drugs were administered orally once per day (11 days) and colitis was induced on the 8th day. Galan reduced the TNBS-induced ulceration, colon mass index, colonic MDA, neutrophils adhesion and infiltration (ICAM-1/MPO), inflammatory mediators (NF-κB, TNF-α, HMGB1, and RAGE), while increased the anti-apoptotic pathway (p-Akt/Bcl-2). Mechanistic study revealed that Galan increased the anti-inflammatory cytokine IL-10, phosphorylated Jak2, while reduced the inflammation controller SOCS3. However, combining MLA with Galan abrogated the beneficial anti-inflammatory/anti-apoptotic signals. The results of the present study indicate that Galan anti-inflammatory/-apoptotic/ -oxidant effects originate from the stimulation of the peripheral α7 nAChR, with the involvement of the Jak2/SOCS3 signaling pathway.

Cilostazol Mediated Nurr1 and Autophagy Enhancement: Neuroprotective Activity in Rat Rotenone PD Model

AbstractNuclear receptor related 1 (Nurr1) orphan receptor has emerged as a promising contender in ameliorating Parkinson’s disease; thus, finding a suitable activator of Nurr1 receptor is an attracting target for treating PD. Cilostazol, a phosphodiesterase-3 inhibitor, recently showed a favorable neuroprotective activity in multiple devastating central disorders, yet the possible antiparkinsonian activity of the drug has not been fully elucidated. Thus, the aim of this study is to explore the neuroprotective effect of cilostazol in rotenone-induced PD model in rats. Cilostazol successfully upregulated Nurr1 expression in PD rats, which resulted in successful preservation of the dopaminergic neuron functionality and integrity as verified by the marked improvement of motor performance in rotarod and open field tests, as well as the increased striatal tyrosine hydroxylase content. Moreover, cilostazol revealed an anti-inflammatory activity as manifested by hampering the global controller of inflammatory signaling pathway, nuclear factor-kappa B, together with its downstream pro-inflammatory cytokines, namely tumor necrosis factor-alpha and interleukin-1 beta, via Nurr-1 upregulation and glycogen synthase kinase 3 beta GSK-3β inhibition. In turn, the increase in GSK-3β inhibited form suppressed the measured downstream apoptotic biomarkers, viz. cytochrome C and caspase-3. Remarkably, cilostazol enhanced autophagy as depicted by hampering both LC3-II and P62 levels possibly through the prominent rise in sirtuin 1 level. In conclusion, cilostazol could be a promising candidate for PD treatment through modulating Nurr1 expression, as well as SIRT-1/autophagy, and GSK-3β/apoptosis cross-regulation. Graphical AbstractIn the rat rotenone model of Parkinson’s disease (PD), Nurr1 expression was downregulated, GSK-3β was activated, and autophagic flux was inhibited. Those deleterious effects were associated with deteriorated motor functions, striatal TH content, enhanced inflammatory state, and apoptotic cascade. Cilostazol, a phosphodiesterase-3 inhibitor, exerted a potential protective effect against PD through Nurr1 enhancement, GSK-3β/apoptosis modulation, and SIRT-1/autophagy enhancement. Nurr1 nuclear receptor related 1, TH tyrosine hydroxylase, NF-κB nuclear factor κB, TNFα tumor necrosis factor alpha, ILs interleukins, GSK-3β glycogen synthase kinase 3 beta, SIRT-1 sirtuin 1.