Mefenamic Acid Loaded and TPGS Stabilized Mucoadhesive Nanoemulsion for the Treatment of Alzheimer's Disease: Development, Optimization, and Brain-Targeted Delivery via Olfactory Pathway.

Alzheimer's disease (AD) is a very common disorder that affects the elderly. There are relatively few medications that can be used orally or as a suspension to treat AD. A mucoadhesive (o/w) nano emulsion of mefenamic acid was made by adding Carbopol 940P to the optimised drug nanoemulsion using distilled water as the aqueous phase (6%); Solutol HS: tween 20 (3.6%) as the surfactant and co-surfactant; and clove oil: TPGS (0.4%) as the oil phase and mefenamic acid as the drug (2.8 mg/ml). The mucoadhesive nanoemulsion (S40.5%w/v) had a particle size of 91.20 nm, polydispersity index of 0.270, and surface charge of - 12.4 mV. Significantly higher (p < 0.001) drug release (89.37%) was observed for mucoadhesive drug formulation in comparison to mucoadhesive drug suspension (25.64%) at 8 h. The ex vivo nasal permeation of 83.03% in simulated nasal fluid and 85.71% in artificial cerebrospinal fluid was observed. The percent inhibition and inhibitory concentration (IC50) of mucoadhesive drug nanoemulsion were found to be 91.57 ± 2.69 and 6.76 respectively. Higher cell viability on glioblastoma cells (85-80%) was researched for mucoadhesive nanoemulsion as compared to drug suspension (80-70%). Significantly higher (p < 0.001) drug absorption and Cmax (491.94 ± 24.13 ng/ml) of mucoadhesive drug nanoemulsion were observed than mucoadhesive drug suspension (107.46 ± 11.46 ng/ml) at 8 h. The stability studies confirmed that the formulation was stable at 40°C ± 2°C and 75 ± 5% RH. The authors concluded that the mucoadhesive mefenamic acid-loaded nanoemulsion may be an effective technique for treating Alzheimer's disease by intranasal route.

Ameliorative role of inducible nitric oxide synthase inhibitors against sodium arsenite-induced renal and hepatic dysfunction in rats.

Arsenic exposure causes immense health distress by increasing risk of cardiovascular abnormalities, diabetes mellitus, neurotoxicity, and nephrotoxicity. The present study explored the role of inducible nitric oxide synthase (iNOS) inhibitors against sodium arsenite-induced renal and hepatic dysfunction in rats. Female Sprague Dawley rats were subjected to arsenic toxicity by administering sodium arsenite (5 mg/kg/day, oral) for 4 weeks. The iNOS inhibitors, S-methylisothiourea (10 mg/kg, i.p.) and aminoguanidine (100 mg/kg, i.p.) were given one hour before sodium arsenite administration in rats for 4 weeks. Sodium arsenite led rise in serum creatinine, urea, uric acid, electrolytes (potassium, fractional excretion of sodium), microproteinuria, and decreased creatinine clearance (p < 0.001) indicated renal dysfunction in rats. Arsenic-intoxication resulted in significant oxidative stress in rat kidneys, which was measured in terms of increase in lipid peroxides, superoxide anion generation and decrease in reduced glutathione (p < 0.001) levels. A threefold increase in renal hydroxyproline level in arsenic intoxicated rats indicated fibrosis. Hematoxylin-eosin staining indicated tubular damage, whereas picrosirius red staining highlighted collagen deposition in rat kidneys. S-methylisothiourea and aminoguanidine improved renal function and attenuated arsenic led renal oxidative stress, fibrosis, and decreased the kidney injury score. Additionally, arsenite-intoxication resulted in significant rise in hepatic parameters (serum aspartate aminotransferase, alanine transferase, alkaline phosphatase, and bilirubin (p < 0.001) along with multi-fold increase in oxidative stress, fibrosis and liver injury score in rats, which was significantly (p < 0.001) attenuated by concurrent administration of iNOS inhibitors). Hence, it is concluded that iNOS inhibitors attenuate sodium arsenite-induced renal and hepatic dysfunction in rats.

Betaine attenuates sodium arsenite-induced renal dysfunction in rats.

Exposure to higher levels of arsenic is a serious threat affecting human health worldwide. We investigated the protective role of betaine (N,N,N-trimethylglycine) against sodium arsenite-induced renal dysfunction in rats. Sodium arsenite (5 mg/kg, oral) was given to rats for 4 weeks to induce nephrotoxicity. Betaine (125 and 250 mg/kg, oral) was administered in rats for 4 weeks along with sodium-arsenite feeding. Arsenic-induced renal dysfunction was demonstrated by measuring serum creatinine, creatinine clearance, urea, uric acid, potassium, fractional excretion of sodium, and microproteinuria. Oxidative stress in rat kidneys was determined by assaying thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione levels. Furthermore, hydroxyproline assay was done to assess renal fibrosis in arsenic intoxicated rats. Hematoxylin-eosin and picrosirius red staining revealed pathological alterations in rat kidneys. Renal endothelial nitric oxide synthase (eNOS) expression was determined by immuno-histochemistry. Concurrent administration of betaine abrogated arsenic-induced renal biochemical and histological changes in rats. Betaine treatment significantly attenuated arsenic-induced decrease in renal eNOS expression. In conclusion, betaine is protective against sodium arsenite-induced renal dysfunction, which may be attributed to its anti-oxidant activity and modulation of renal eNOS expression in rat kidneys.

Umbelliferone attenuates glycerol-induced myoglobinuric acute kidney injury through peroxisome proliferator-activated receptor-γ agonism in rats.

Rhabdomyolysis is a clinical syndrome caused by damage to skeletal muscle, which consequently releases breakdown products into circulation and causes acute kidney injury (AKI) in humans. Intramuscular injection of glycerol mimics rhabdomyolysis and associated AKI. In this study, we explored the role of umbelliferone against glycerol-induced AKI in rats. Kidney function was assessed by measuring serum creatinine, urea, electrolytes, and microproteinuria. Renal oxidative stress was quantified using thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione assay. Renal histological changes were determined using periodic acid Schiff and hematoxylin-eosin staining, and immunohistology of apoptotic markers (Bax, Bcl-2) was done. Serum creatine kinase was quantified to assess glycerol-induced muscle damage. Umbelliferone attenuated glycerol-induced change in biochemical parameters, oxidative stress, histological alterations, and renal apoptosis. Pretreatment with bisphenol A diglycidyl ether, a peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist, attenuated umbelliferone-mediated protection. It is concluded that umbelliferone attenuates glycerol-induced AKI possibly through PPAR-γ agonism in rats.

Stevioside protects against rhabdomyolysis-induced acute kidney injury through PPAR-γ agonism in rats.

We explored the potential role of peroxisome proliferator activated receptor-γ (PPAR-γ) in stevioside-mediated renoprotection using rhabdomyolysis-induced acute kidney injury (AKI) model in rats. Rhabdomyolysis refers to intense skeletal muscle damage, which further causes AKI. Glycerol (50% w/v, 8 ml/kg) was injected intramuscularly in rats to induce rhabdomyolysis. After 24 hr, AKI was demonstrated by quantifying serum creatinine, urea, creatinine clearance, microproteinuria, and electrolytes in rats. Further, oxidative stress was measured by assaying thiobarbituric acid reactive substances, generation of superoxide anion, and reduced glutathione levels. Additionally, serum creatine kinase (CK) level was assayed to determine glycerol-induced muscle damage in rats. Pathological changes in rat kidneys were studied using hematoxylin-eosin and periodic acid Schiff staining. Moreover, the expression of apoptotic markers (Bcl-2, Bax) in rat kidneys was demonstrated by immunohistochemistry. Stevioside (10, 25, and 50 mg/kg) was administered to rats, prior to the induction of AKI. In a separate group, bisphenol A diglycidyl ether (BADGE, 30 mg/kg), a PPAR-γ receptor antagonist was given prior to stevioside administration, which was followed by rhabdomyolysis-induced AKI in rats. The significant alteration in biochemical and histological parameters in rats indicated AKI, which was attenuated by stevioside treatment. Pretreatment with BADGE abrogated stevioside-mediated renoprotection, which is suggestive of the involvement of PPAR-γ in its renoprotective effect. In conclusion, stevioside protects against rhabdomyolysis-induced AKI, which may be attributed to modulation of PPAR-γ expression.

Fenofibrate attenuates ischemia reperfusion-induced acute kidney injury and associated liver dysfunction in rats.

Ischemia/reperfusion (I/R) is one of the common reasons for acute kidney injury (AKI) and we need to develop effective therapies for treating AKI. We investigated the role of fenofibrate against I/R-induced AKI and associated hepatic dysfunction in rats. In male wistar albino rats, renal pedicle occlusion for 40 min and 24 h reperfusion resulted in AKI. I/R-induced AKI was demonstrated by measuring serum creatinine, creatinine clearance, urea, uric acid, potassium, fractional excretion of sodium and urinary microproteins. Oxidative stress in rat kidneys was quantified by assaying superoxide anion generation, thiobarbituric acid reactive substances, and reduced glutathione levels. AKI-induced hepatic damage was quantified by assaying serum aminotransferases, alkaline phosphatase and bilirubin levels. Moreover, serum cholesterol, high density lipoprotein and triglycerides were quantified. Hematoxylin-eosin staining of renal and hepatic tissues was done and the kidney and liver injury scores were determined. Immunohistology of endothelial nitric oxide synthase (eNOS) was done in rat kidneys. Fenofibrate was administered for 1 week before subjecting rats to AKI. In separate group, the nitric oxide synthase inhibitor, L-nitroarginine methyl ester (L-NAME) was administered prior to fenofibrate treatment. In I/R group, significant alteration in the serum/urine parameters indicated AKI and hepatic dysfunction along with marked increase in kidney and liver injury scores. Treatment with fenofibrate attenuated AKI and associated hepatic dysfunction. Moreover, I/R-induced decrease in renal eNOS expression was abrogated by fenofibrate. Pre-treatment with L-NAME abolished fenofibrate mediated reno- and hepato-protective effects. In conclusion, fenofibrate attenuates I/R-induced AKI and associated hepatic dysfunction putatively through modulation of eNOS expression.

Sildenafil obviates ischemia-reperfusion injury-induced acute kidney injury through peroxisome proliferator-activated receptor γ agonism in rats.

BACKGROUND: Sildenafil is a phosphodiesterase inhibitor used clinically for treating erectile dysfunction. Few studies suggest sildenafil to be a renoprotective agent. The present study investigated the involvement of peroxisome proliferator-activated receptor γ (PPAR-γ) in sildenafil-mediated protection against ischemia-reperfusion-induced acute kidney injury (AKI) in rats. MATERIALS AND METHODS: The rats were subjected to ischemia-reperfusion injury (IRI) with 40 min of bilateral renal ischemia followed by reperfusion for 24 h. The renal damage was assessed by measuring creatinine clearance, blood urea nitrogen, plasma uric acid, electrolytes, and microproteinuria in rats. The thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione levels were measured to assess oxidative stress in renal tissues. The hematoxylin-eosin staining was carried out to demonstrate histopathologic changes in renal tissues. Sildenafil (0.5 and 1.0 mg/kg, intraperitoneal) was administered 1 h before subjecting the rats to renal IRI. In a separate group, bisphenol A diglycidyl ether (30 mg/kg, intraperitoneal), a PPAR-γ receptor antagonist, was given before sildenafil administration followed by IRI. RESULTS: The ischemia-reperfusion demonstrated marked AKI with significant changes in serum and urinary parameters, enhanced oxidative stress, and histopathologic changes in renal tissues. The administration of sildenafil demonstrated significant protection against ischemia-reperfusion-induced AKI. The prior treatment with bisphenol A diglycidyl ether abolished sildenafil-mediated renal protection, thereby confirming involvement of PPAR-γ agonism in the sildenafil-mediated renoprotective effect. CONCLUSIONS: It is concluded that sildenafil protects against ischemia-reperfusion-induced AKI through PPAR-γ agonism in rats.

Curcumin alleviates ischemia reperfusion-induced acute kidney injury through NMDA receptor antagonism in rats.

OBJECTIVE: The present study investigated the role of N-methyl-d-aspartate (NMDA) receptors in curcumin-mediated renoprotection against ischemia reperfusion (I/R)-induced acute kidney injury (AKI) in rats. METHODS: Rats were subjected to bilateral renal I/R (40 min I, 24 hours R) to induce AKI. Kidney injury was assessed by measuring creatinine clearance, blood urea nitrogen, plasma uric acid, potassium level, fractional excretion of sodium, and macroproteinuria. Oxidative stress in renal tissues was assessed by measuring myeloperoxidase activity, thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione content. Hematoxylin & eosin staining was done to assess histological changes in renal tissues. Curcumin (30 and 60 mg/kg) was administered one hour before subjecting rats to AKI. In separate groups, NMDA receptor agonists, glutamic acid (200 mg/kg), and spermidine (20 mg/kg) were administered prior to curcumin treatment in rats followed by AKI. RESULTS: I/R-induced AKI was demonstrated by significant change in plasma and urine parameters along with marked increase in oxidative stress and histological changes in renal tissues that were aggravated with pretreatment of glutamic acid and spermidine in rats. Administration of curcumin resulted in significant protection against AKI. However, glutamic acid and spermidine pretreatments prevented curcumin-mediated renoprotection. CONCLUSION: It is concluded that NMDA receptor antagonism significantly contributes towards curcumin-mediated protection against I/R-induced AKI.

Glycine aggravates ischemia reperfusion-induced acute kidney injury through N-Methyl-D-Aspartate receptor activation in rats.

The present study was designed to investigate the role of glycine in ischemia reperfusion-induced acute kidney injury (AKI) in rats. The AKI was induced in rats by occluding renal pedicles for 40 min followed by reperfusion for 24 h. The AKI was assessed by measuring creatinine clearance, blood urea nitrogen, plasma uric acid, potassium, fractional excretion of sodium, and microproteinuria. The oxidative stress in renal tissues was assessed by quantification of myeloperoxidase activity, thiobarbituric acid-reactive substances, superoxide anion generation, and reduced glutathione level. Glycine (100, 200, and 400 mg/kg, i.p.) was administered to rats 30 min before subjecting to AKI. The glycinergic receptor blocker, strychnine (0.75 mg/kg i.p.), and glycine-binding site blocker at N-methyl-D-aspartate (NMDA) receptor, kynurenic acid (300 and 600 mg/kg i.p.), were used in the present study. The ischemia reperfusion induced AKI as witnessed by significant change in plasma, urinary, and tissue parameters employed in the present study. Glycine treatment increased ischemia reperfusion-induced AKI. The treatment with strychnine did not show any protection, whereas kynurenic acid ameliorated renal ischemia reperfusion-induced AKI. The results obtained in present study suggest that glycine increases ischemia reperfusion-induced renal damage through NMDA receptor agonism rather than strychnine-sensitive glycinergic receptors. Hence, it is concluded that glycine aggravates ischemia reperfusion-induced AKI. In addition, the activation of strychnine-insensitive glycine-binding site of NMDA receptors is responsible for its renal-damaging effect rather than strychnine-sensitive glycinergic receptors.

Role of progesterone in melatonin-mediated protection against acute kidney injury.

BACKGROUND: Melatonin is released by pineal gland and maintains circadian rhythm in the body. It has been reported as renoprotective agent because of its antioxidant property. Recently, a cross talk between progesterone and melatonin has been observed in various preclinical studies. The present study investigated the involvement of progesterone receptors in melatonin-mediated protection against ischemia reperfusion induced acute kidney injury (AKI) in rats. MATERIALS AND METHODS: The rats were subjected to bilateral renal ischemia for 40 min followed by reperfusion for 24 h to induce AKI. The AKI was assessed by measuring creatinine clearance, serum urea, uric acid level, potassium level, fractional excretion of sodium, lactate dehydrogenase activity, and microproteinuria. The oxidative stress in renal tissues was assessed by quantification of myeloperoxidase activity, thiobarbituric acid reactive substances, superoxide anion generation, reduced glutathione level, and catalase activity. The hematoxylin-eosin staining was carried out to observe histopathologic changes in renal tissues. The melatonin (4 and 10 mg/kg, intraperitoneally) and progesterone receptor antagonist mifepristone (5 mg/kg, intraperitoneally) were used in the present study. RESULTS: The renal ischemia reperfusion induced AKI as indicated by significant change in serum, urinary, and tissue parameters that was ameliorated by prior treatment with melatonin. No significant difference in serum progesterone level was observed between various groups used in the present study. The prior administration of mifepristone abolished melatonin-mediated protection against AKI. CONCLUSIONS: It is concluded that melatonin treatment affords protection against ischemia reperfusion induced AKI. Moreover, progesterone receptors are essentially involved in mediating protective role of melatonin against AKI in rats.

Involvement of progesterone receptors in ascorbic acid-mediated protection against ischemia-reperfusion-induced acute kidney injury.

BACKGROUND: Ascorbic acid (AA) is an established antioxidant and has been used for treatment of various disorders. Recent reports suggest that administration of AA increases the level of steroids such as progesterone in the body. The present study investigated the protective role of progesterone against ischemia-reperfusion-induced acute kidney injury (AKI) and possible involvement of progesterone receptors in AA-mediated renoprotection in rats. MATERIALS AND METHODS: The male rats were subjected to bilateral renal ischemia for 40 min followed by reperfusion for 24 h to induce AKI. The rats were treated with progesterone (5 and 10 mg/kg, intraperitoneally) and AA (500 mg/kg, intraperitoneally for 1, 2, and 5 d) before AKI. In separate groups, mifepristone, the progesterone receptor antagonist was administered to rats before progesterone (10 mg/kg) and AA treatment (5 d). Various parameters including creatinine clearance, serum urea, uric acid, potassium level, fractional excretion of sodium, lactate dehydrogenase, and microproteinuria were used to assess kidney injury. Moreover, renal tissues were subjected to quantification of oxidative stress and evaluation of histopathologic changes. RESULTS: The exogenous administration of progesterone afforded protection against AKI in a dose-dependent manner that was abolished by mifepristone. The administration of AA for 1, 2, and 5 d induced significant increase in serum progesterone levels and afforded protection against AKI. The antioxidant and renoprotective effect of AA was abolished by prior treatment with mifepristone. CONCLUSIONS: It is concluded that exogenous administration of progesterone exerts significant antioxidant and renoprotective effect. Moreover, the progesterone receptors find their explicit involvement in AA-mediated renoprotection against ischemia-reperfusion-induced AKI in rats.

Effect of modulating the allosteric sites of N-methyl-D-aspartate receptors in ischemia-reperfusion induced acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is one of the major health problems in developed as well as developing countries. The literature regarding the role of N-methyl-D-aspartate receptors (NMDAR) and the impact of the modulation of its allosteric sites on renal function is inadequate. The present study investigated the effect of modulating allosteric sites of NMDAR in ischemia-reperfusion-induced AKI. MATERIALS AND METHODS: We subjected rats to bilateral renal ischemia for 40 min followed by reperfusion for 24 h to induce AKI. We measured blood urea nitrogen, serum creatinine, uric acid, and lactate dehydrogenase to assess kidney injury. We assayed the thiobarbituric acid-reactive substances, reduced glutathione level, and myeloperoxidase and catalase activity to assess oxidative stress in renal tissue, and used hematoxylin-eosin staining to observe histopathologic changes. RESULTS: Ischemia-reperfusion induced AKI, as demonstrated by an increase in serum parameters, oxidative stress and histopathologic changes in renal tissue. The NMDA agonist glutamic acid and polyamine binding site agonist spermidine significantly aggravated oxidative stress and ischemia-reperfusion-induced AKI. Various NMDA receptor antagonists, including glycine binding site inhibitor kynurenic acid, polyamine binding site inhibitor ketamine, and channel blocking agent magnesium sulfate, attenuated ischemia-reperfusion-induced AKI and significantly reduced oxidative stress, which suggests a role for NMDA receptors and the importance of regulating its allosteric sites in AKI. CONCLUSIONS: Acute kidney injury is associated with the activation of NMDA receptors, as well as significant oxidative stress. The antagonism of various allosteric sites of NMDA receptors affords significant benefit against ischemia-reperfusion-induced AKI.

Involvement of peroxisome proliferator-activated receptor gamma in vitamin D-mediated protection against acute kidney injury in rats.

BACKGROUND: Vitamin D has been reported as renoprotective agents in various studies. Recently, a few in vitro studies highlighted cross talk between vitamin D and peroxisome proliferator-activated receptor gamma (PPAR-γ). The present study investigated the activation of PPAR-γ as novel mechanism in vitamin D-mediated protection against ischemia reperfusion-induced acute kidney injury (AKI) in rats. MATERIALS AND METHODS: The AKI was induced by clamping renal pedicles for 40 min followed by reperfusion for 24 h. The AKI was assessed by measuring creatinine clearance, serum urea, uric acid level, and lactate dehydrogenase activity. Moreover, serum potassium, calcium level, fractional excretion of sodium, and microproteinuria were measured in rats. The oxidative stress in renal tissues was assessed by quantification of thiobarbituric acid-reactive substances, superoxide anion generation, reduced glutathione level, and catalase and myeloperoxidase activities. The hematoxylin-eosin staining was carried out to observe histopathologic changes in renal tissues. Vitamin D (0.25, 0.5, and 1 µg/kg) was administered for 7 d before subjecting rats to renal ischemia reperfusion injury (IRI). RESULTS: The renal IRI in rats induced significant changes in serum, urinary, and oxidative stress parameters in renal tissues. Moreover, hematoxylin-eosin staining revealed marked damage produced by IRI in renal tissues. The administration of vitamin D at 0.5 µg/kg dose afforded maximum protection against renal IRI. The prior treatment with PPAR-γ antagonist bisphenol A diglycidyl ether significantly attenuated protective effect of vitamin D, thus confirming involvement of PPAR-γ in vitamin D-mediated renoprotection. CONCLUSIONS: It is concluded that activation of PPAR-γ significantly contributes toward vitamin D-mediated protection against ischemia reperfusion-induced AKI.

Effect of vinpocetine alone and in combination with enalapril in experimental model of diabetic cardiomyopathy in rats: possible involvement of PDE-1/TGF-ß/ Smad 2/3 signalling pathways.

OBJECTIVE: Diabetic cardiomyopathy (DC) is one of the severe secondary complications of diabetes mellitus in humans. Vinpocetine is an alkaloid having pleiotropic pharmacological effects. The present study is designed to investigate the effect of vinpocetine in DC in rats. METHODS: Rats were fed a high-fat diet for nine weeks along with single dose of streptozotocin after the second week to induce DC. The haemodynamic evaluation was performed to assess the functional status of rats using the Biopac system. Cardiac echocardiography, biochemical, oxidative stress parameters and inflammatory cytokine level were analysed in addition to haematoxylin-eosin and Masson's trichome staining to study histological changes, cardiomyocyte diameter and fibrosis, respectively. Phosphodiesterase-1 (PDE-1), transforming growth factor-ß (TGF-ß) and p-Smad 2/3 expression in cardiac tissues were quantified using western blot/RT-PCR. KEY FINDING: Vinpocetine treatment and its combination with enalapril decreased the glucose levels compared to diabetic rats. Vinpocetine improved the echocardiographic parameters and cardiac functional status of rats. Vinpocetine decreased the cardiac biochemical parameters, oxidative stress, inflammatory cytokine levels, cardiomyocyte diameter and fibrosis in rats. Interestingly, expressions of PDE-1, TGF-ß and p-Smad 2/3 were ameliorated by vinpocetine alone and in combination with enalapril. CONCLUSIONS: Vinpocetine is a well-known inhibitor of PDE-1 and the protective effect of vinpocetine in DC is exerted by inhibition of PDE-1 and subsequent inhibition of the expression of TGF-ß/Smad 2/3.

Ameliorative Role of Diallyl Disulfide Against Glycerol-induced Nephrotoxicity in Rats.

INTRODUCTION: This study investigated the role of diallyl disulfide (DADS) against glycerol-induced nephrotoxicity in rats. Moreover, the role of peroxisome proliferator activated receptor-γ (PPAR-γ) in DADS-mediated renoprotection has been explored. MATERIALS AND METHODS: Male Wistar albino rats were challenged with glycerol (50% w/v, 8 mL/kg intramuscular) to induce nephrotoxicity. Kidney injury was quantified by measuring serum creatinine, creatinine clearance, urea, potassium, fractional excretion of sodium, and microproteinuria in rats. Renal oxidative stress was measured in terms of thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione levels. Hematoxylin-eosin (H&E) and periodic acid Schiff staining of renal samples was done to show histological changes. Glycerol-induced muscle damage was quantified by assaying creatine kinase (CK) levels in rat serum. RESULTS: Administration of glycerol resulted in muscle damage as reflected by significant rise in CK levels in rats. Glycerol intoxication led kidney damage was reflected by significant change in renal biochemical parameters, renal oxidative stress and histological changes in rat kidneys. Administration of DADS attenuated glycerol-induced renal damage. Notably, pretreatment with bisphenol A diglycidyl ether, a PPAR-γ antagonist, abolished DADS renoprotection in rats. CONCLUSION: We conclude that DADS affords protection against glycerol-induced renal damage in rats. Moreover, PPAR-γ plays a key role in DADS-mediated renoprotective effect.

Ameliorative role of bosentan, an endothelin receptor antagonist, against sodium arsenite-induced renal dysfunction in rats.

Arsenic exposure is well documented to cause serious health hazards, such as cardiovascular abnormalities, neurotoxicity and nephrotoxicity. In the present study, we intended to explore the role of bosentan, an endothelial receptor antagonist, against sodium arsenite-induced nephrotoxicity and hepatotoxicity in rats. Sodium arsenite (5 mg/kg, oral) was administered for 4 weeks to induce renal dysfunction in rats. Sodium arsenite intoxicated rats were treated with bosentan (50 and 100 mg/kg, oral) for 4 weeks. Arsenic led renal damage was demonstrated by significant increase in serum creatinine, urea, uric acid, potassium, fractional excretion of sodium, microproteinuria and decreased creatinine clearance in rats. Sodium arsenite resulted in marked oxidative stress in rat kidneys as indicated by profound increase in lipid peroxides, and superoxide anion generation alongwith decrease in reduced glutathione levels. Hydroxyproline assay highlighted arsenic-induced renal fibrosis in rats. Hematoxylin-eosin staining indicated glomerular and tubular changes in rat kidneys. Picrosirius red staining highlighted collagen deposition in renal tissues of arsenic treated rats. Immunohistological results demonstrated the reduction of renal eNOS expression in arsenic treated rats. Notably, treatment with bosentan attenuated arsenic-induced renal damage and resisted arsenic-led reduction in renal eNOS expression. In addition, sodium arsenite-induced alteration in hepatic parameters (serum aspartate aminotransferase, alanine transferase, alkaline phosphatase, bilirubin), oxidative stress and histological changes were abrogated by bosentan treatment in rats. Hence, we conclude that bosentan treatment attenuated sodium arsenite-induced oxidative stress, fibrosis and reduction in renal eNOS expression in rat kidneys. Moreover, bosentan abrogated arsenic led hepatic changes in rats.

Ameliorative role of rosiglitazone in hyperhomocysteinemia-induced experimental cardiac hypertrophy.

The present study has been designed to explore the beneficial effect of rosiglitazone, a peroxisome proliferator activated receptor-gamma agonist, in hyperhomocysteinemia-induced cardiac hypertrophy in rats. The hyperhomocysteinemia was induced in rats by feeding L-methionine (1.7 g/kg per day orally) for 8 weeks. The development of cardiac hypertrophy was assessed by measuring ratio of left ventricular weight to body weight, left ventricular wall thickness, cardiomyocyte diameter, and mean arterial blood pressure. The extent of fibrosis was checked by biochemical and histological assessment of collagen deposition. Moreover, the oxidative stress in heart was measured in terms of an increase in thiobarbituric acid reactive substances, superoxide anion generation, and decrease in reduced glutathione levels. The treatment with rosiglitazone (5 and 10 mg/kg per day orally) started from the first day of administration of L-methionine significantly abolished hyperhomocysteinemia-induced increase in left ventricular weight to body weight ratio, left ventricular wall thickness, cardiomyocyte diameter, collagen deposition, and oxidative stress without affecting serum homocysteine levels in rats. At high dose, rosiglitazone markedly reduced mean arterial blood pressure but at low dose, a significant reduction in mean arterial blood pressure was not observed in hyperhomocysteinemic rats. Hence, our results suggest that rosiglitazone provides benefit in hyperhomocysteinemia-induced cardiac hypertrophy and fibrosis in a dose-dependent manner and its protective action is independent of change in mean arterial blood pressure and serum homocysteine levels in rats.

Potential target sites to modulate vascular endothelial dysfunction: current perspectives and future directions.

Endothelium is innermost lining of the blood vessel and it regulates the vascular tone. It plays a critical role in the mechanics of blood flow, regulation of coagulation, leukocyte adhesion, vascular smooth muscle cell (VSMC) growth and immune function. Endothelial dysfunction results in reduced vasodilatation, proinflammatory state and prothrombotic properties. Various experimental evidences revealed that reduced nitric oxide production and increased oxidative stress lead to vascular endothelial dysfunction (VED). Environmental factors such as cigarette smoking, alcohol consumption and exposure to arsenic play a critical role in the development of endothelial dysfunction. Vascular endothelial dysfunction is a hallmark for various cardiovascular disorders such as hypertension, atherosclerosis, heart failure, myocardial infarction and stroke. However, the pathological mechanism involved in the vascular endothelial dysfunction is poorly understood. The present review delineates various potential target sites for vascular endothelial dysfunction, which may open a new vista for exploring novel pharmacological agents to treat various cardiovascular disorders.

Mast cell stabilizers obviate high fat diet-induced renal dysfunction in rats.

The present study investigated the infiltration of mast cells into the kidney tissue and the preventive role of mast cell stabilizers against high fat diet (HFD)-induced renal injury in rats. The animals were fed on HFD (30% fat) for 12 consecutive weeks to induce renal injury. The HFD-induced obesity was assessed by calculating obesity index, adiposity index, and estimation of total cholesterol, triglycerides, and high density lipoproteins in plasma. The renal dysfunction was evaluated by measuring creatinine clearance, blood urea nitrogen, uric acid, electrolytes and microproteinuria. The oxidative stress in renal tissues was determined by myeloperoxidase activity, thiobarbituric acid reactive substances, superoxide anion generation and reduced glutathione level. The systolic blood pressure (SBP) was monitored using non-invasive blood pressure measuring apparatus. Histamine and hydroxyproline contents were quantified in renal tissues. Gross histopathological changes, mast cell density and collagen deposition in the renal tissue was determined by means of histopathology. The mast cell stabilizers, sodium cromoglycate and ketotifen were administered daily for 12 weeks. The HFD fed rats demonstrated significant increase in lipid profile, kidney injury with marked increase in renal oxidative stress, SBP, mast cell density, histamine content and hydroxyproline content that was attenuated by sodium cromoglycate and ketotifen treatment. Hence, the novel findings of this investigation suggest that HFD induced mast cells infiltration into kidney tissue seems to play an important role in renal pathology, and treatment with mast cell stabilizers serves as potential therapy in management of HFD induced renal dysfunction in rats.

Dipyridamole attenuates ischemia reperfusion induced acute kidney injury through adenosinergic A1 and A2A receptor agonism in rats.

Dipyridamole (DYP) is an anti-platelet agent with marked vasodilator, anti-oxidant, and anti-inflammatory activity. The present study investigated the role of adenosine receptors in DYP-mediated protection against ischemia reperfusion-induced acute kidney injury (AKI) in rats. The rats were subjected to bilateral renal ischemia for 40 min followed by reperfusion for 24 h. The renal damage induced by ischemia reperfusion injury (IRI) was assessed by measuring creatinine clearance, blood urea nitrogen, uric acid, plasma potassium, fractional excretion of sodium, and microproteinuria in rats. The oxidative stress in renal tissues was assessed by quantification of thiobarbituric acid-reactive substances, superoxide anion generation, and reduced glutathione level. The hematoxylin-eosin staining was carried out to observe histopathological changes in renal tissues. DYP (10 and 30 mg/kg, intraperitoneal, i.p.) was administered 30 min before subjecting the rats to renal IRI. In separate groups, caffeine (50 mg/kg, i.p.), an adenosinergic A1 and A2A receptor antagonist was administered with and without DYP treatment before subjecting the rats to renal IRI. The ischemia reperfusion-induced AKI was demonstrated by significant changes in serum as well as urinary parameters, enhanced oxidative stress, and histopathological changes in renal tissues. The administration of DYP demonstrated protection against AKI. The prior treatment with caffeine abolished DYP-mediated reno-protection suggesting role of A1 and A2A adenosine receptors in DYP-mediated reno-protection in rats. It is concluded that adenosine receptors find their definite involvement in DYP-mediated anti-oxidative and reno-protective effect against ischemia reperfusion-induced AKI.