Effect of alpha-lipoic acid supplementation on blood pressure, renal oxidant-antioxidant status and renal damage in spontaneously hypertensive rats

Objective: To investigate the effect of alpha-lipoic acid (ALA) supplementation on systolic blood pressure (SBP), renal oxidant-antioxidant status and renal damage in spontaneously hypertensive rats (SHR) and SHR administered with Nω-nitro-L-arginine methyl ester (L-NAME). Methods: Male rats were divided into four groups (SHR, SHR+ALA, SHR+L-NAME, SHR+ALA+L-NAME). The respective group of rats was administered with ALA (100 mg/kg/day) from age 4 weeks to 28 weeks and L-NAME (25 mg/kg/day) from age 16 weeks to 28 weeks. SBP was measured every two weeks and twenty four hour urine was collected at 4 weeks, 16 weeks and 28 weeks for estimation of protein, creatinine and N-acetyl-β-D-glucosaminidase. At the end of 28 weeks, rats were sacrificed and blood and kidneys collected for assessment of blood creatinine, kidney thiobarbituric acid reactive substances, protein carbonyls, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, glutathione disulfide, glutathione, total antioxidant status and nitric oxide as well as histopathological examination. Results: ALA supplementation significantly reduced SBP of SHR and SHR+L-NAME rats when compared to their respective non-supplemented groups. Renal oxidant status markers including thiobarbituric acid reactive substances and protein carbonyls were significantly reduced on SHR and SHR+L-NAME rats supplemented with ALA at 28 weeks as well as ALA supplementation significantly increased renal antioxidants including superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione and glutathione/glutathione disulfide ratio at 28 weeks. No significant change in nitric oxide levels was observed between the ALA supplemented and non-supplemented groups. Renal dysfunction was ameliorated on ALA supplementation as evidenced by significant reduction in urine protein levels, N-acetyl-β-D-glucosaminidase activity and significant increase of creatinine clearance in SHR and SHR+L-NAME at 28 weeks. Renal histopathological examination showed that ALA supplementation prevented vascular damage in SHR and ameliorated glomerular damage in SHR+L-NAME at 28 weeks. Conclusions: ALA has hypotensive and renoprotective effects on both SHR and SHR+L-NAME, which could be due to its ability to ameliorate oxidative stress in the kidneys.

Effect of Antihypertensive Drug Treatment on Oxidative Stress Markers in Heart of Spontaneously Hypertensive Rat Models.

Oxidative stress has been suggested to play a role in hypertension- and hypertension-induced organ damage. The effect of antihypertensive drug treatments on oxidative stress markers has not been well assessed. Therefore, in this study we investigated the effect of enalapril on oxidative stress markers in hearts of hypertensive rat models such as spontaneously hypertensive rats (SHR) and SHRs administered N-nitro-L-arginine methyl ester (SHR+L-NAME rats). Male rats were divided into four groups: SHRs, SHR+enalapril (SHR-E) rats, SHR+L-NAME rats, SHR+enalapril+L-NAME (SHRE+L-NAME) rats. Rats (SHREs) were administered enalapril (30 mg kg-1 day-1) in drinking water from week 4 to week 28 and L-NAME (25 mg kg-1 day-1) from week 16 to week 28 in drinking water. At the end of 28 weeks, animals were sacrificed, and their hearts were collected for the assessment of oxidative stress markers and histological examination. Enalapril treatment significantly enhanced the total antioxidant status (TAS) (P < 0.001), reduced the oxidized glutathione ratio (GSH : GSSG) (P < 0.001), and reduced to thibarbituric acid reactive substances (TBARS) (P < 0.001) and protein carbonyl content (PCO) (P < 0.001), which thus reduced the oxidative stress in the heart. The fibrosis areas in SHRs and SHR+L-NAME rats were also markedly reduced. These findings suggest that enalapril might play a protective role in hypertension- and hypertension-induced organ damage.

Restoration of glutamine synthetase activity, nitric oxide levels and amelioration of oxidative stress by propolis in kainic acid mediated excitotoxicity.

BACKGROUND: Propolis has been proposed to be protective on neurodegenerative disorders. To understand the neuroprotective effects of honeybee propolis, glutamine synthetase (GS) activity, nitric oxide (NO), thiobarbituric acid reactive substances (TBARS) and total antioxidant status (TAS) were studied in different brain regions-cerebral cortex (CC), cerebellum (CB) and brain stem (BS) of rats supplemented with propolis and subjected to kainic acid (KA) mediated excitotoxicity. MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into four groups; Control group and KA group received vehicle and saline. Propolis group and propolis + KA group were orally administered with propolis (150mg/kg body weight), five times every 12 hours. KA group and propolis + KA group were injected subcutaneously with kainic acid (15mg/kg body weight) and were sacrificed after 2 hrs and CC, CB and BS were separated homogenized and used for estimation of GS activity, NO, TBARS, and TAS concentrations by colorimetric methods. Results were analyzed by one-way ANOVA, reported as mean + SD from 6 animals, and p<0.05 considered statistically significant. RESULTS: NO was increased (p< 0.001) and GS activity was decreased (p< 0.001) in KA treated group compared to control group as well as propolis + KA treated group. TBARS was decreased and TAS was increased (p< 0.001) in propolis + KA treated group compared KA treated group. CONCLUSION: This study clearly demonstrated the restoration of GS activity, NO levels and decreased oxidative stress by propolis in kainic acid mediated excitotoxicity. Hence the propolis can be a possible potential candidate (protective agent) against excitotoxicity and neurodegenerative disorders.

Propolis ameliorates tumor nerosis factor-α, nitric oxide levels, caspase-3 and nitric oxide synthase activities in kainic acid mediated excitotoxicity in rat brain.

BACKGROUND: Increased nitric oxide (NO), neuronal inflammation and apoptosis have been proposed to be involved in excitotoxicity plays a part in many neurodegenerative diseases. To understand the neuro-protective effects of propolis, activities of Nitric oxide synthase (NOS) and caspase-3 along with NO and tumor necrosis factor-α (TNF-α) levels were studied in cerebral cortex (CC), cerebellum (CB) and brain stem (BS) in rats supplemented with propolis prior to excitotoxic injury with kainic acid (KA). MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into four groups (n=6 rats per group) as Control, KA, Propolis and KA+Propolis. The control group and KA group have received vehicle and saline. Propolis group and propolis + KA group were orally administered with propolis (150 mg/kg body weight), five times every 12 hours. KA group and propolis +KA group were injected subcutaneously with kainic acid (15 mg/kg body weight) and were sacrificed after 2 hrs. CC, CB and BS were separated, homogenized and used for estimation of NOS, caspase-3, NO and TNF-α by commercial kits. Results were analyzed by one way ANOVA, reported as mean + SD (n=6 rats), and p<0.05 was considered statistically significant. RESULTS: The concentration of NO, TNF-α, NOS and caspase-3 activity were increased significantly (p<0.001) in all the three brain regions tested in KA group compared to the control. Propolis supplementation significantly (p<0.001) prevented the increase in NOS, NO, TNF-α and caspase-3 due to KA. CONCLUSION: Results of this study clearly demonstrated that the propolis supplementation attenuated the NOS, caspase-3 activities, NO, and TNF-α concentration and in KA mediated excitotoxicity. Hence propolis can be a possible potential protective agent against excitotoxicity and neurodegenerative disorders.

Effect of Clonidine (an antihypertensive drug) treatment on oxidative stress markers in the heart of spontaneously hypertensive rats.

Hypertension is a risk factor for several cardiovascular diseases and oxidative stress suggested to be involved in the pathophysiology. Antihypertensive drug Clonidine action in ameliorating oxidative stress was not well studied. Therefore, this study investigate the effect of Clonidine on oxidative stress markers and nitric oxide (NO) in SHR and nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME) administered SHR. Male rats were divided into four groups [SHR, SHR+Clonidine (SHR-C), SHR+L-NAME, SHR+Clonidine+L-NAME(SHRC+L-NAME)]. Rats (SHRC) were administered with Clonidine (0.5 mg kg(-1) day(-1)) from 4 weeks to 28 weeks in drinking water and L-NAME (25 mg kg(-1) day(-1)) from 16 weeks to 28 weeks to SHRC+L-NAME. Systolic blood pressure (SBP) was measured. At the end of 28 weeks, all rats were sacrificed and in their heart homogenate, oxidative stress parameters and NO was assessed. Clonidine treatment significantly enhanced the total antioxidant status (TAS) (P < 0.001) and reduced the thibarbituric acid reactive substances (TBARS) (P < 0.001) and protein carbonyl content (PCO) (P < 0.05). These data suggest that oxidative stress is involved in the hypertensive organ damage and Clonidine not only lowers the SBP but also ameliorated the oxidative stress in the heart of SHR and SHR+L-NAME.

Decreased glutamine synthetase, increased citrulline–nitric oxide cycle activities, and oxidative stress in different regions of brain in epilepsy rat model

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To understand their role in epilepsy, the nitric oxide synthetase (NOS), argininosuccinate synthetase (AS), argininosuccinate lyase (AL), glutamine synthetase (GS), and arginase activities, along with the concentration of nitrate/nitrite (NOx), thiobarbituric acid reactive substances (TBARS), and total antioxidant status (TAS), were estimated in different regions of brain in rats subjected to experimental epilepsy induced by subcutaneous administration of kainic acid (KA). The short-term (acute) group animals were killed after 2 h and the long term (chronic) group animals were killed after 5 days of single injection of KA (15 mg/kg body weight). After decapitation of rats, the brain regions were separated and in their homogenates, the concentration of NOx, TBARS and TAS and the activities of NOS, AS, AL, arginase and glutamine synthetase were assayed by colorimetric methods. The results of the study demonstrated the increased activity of NOS and formation of NO in acute and chronic groups epilepsy. The activities of AS and AL were increased and indicate the effective recycling of citrulline to arginine. The activity of glutamine synthetase was decreased in acute and chronic groups of epilepsy compared to control group and indicate the modulation of its activity by NO in epilepsy. The activity of arginase was not changed in acute group; however it was decreased in chronic group and may favor increased production of NO in this condition. The concentration TBARS were increased and TAS decreased in acute and chronic groups of epilepsy and supports the oxidative stress in epilepsy (AU)

Decreased glutamine synthetase, increased citrulline-nitric oxide cycle activities, and oxidative stress in different regions of brain in epilepsy rat model.

To understand their role in epilepsy, the nitric oxide synthetase (NOS), argininosuccinate synthetase (AS), argininosuccinate lyase (AL), glutamine synthetase (GS), and arginase activities, along with the concentration of nitrate/nitrite (NOx), thiobarbituric acid reactive substances (TBARS), and total antioxidant status (TAS), were estimated in different regions of brain in rats subjected to experimental epilepsy induced by subcutaneous administration of kainic acid (KA). The short-term (acute) group animals were killed after 2 h and the long term (chronic) group animals were killed after 5 days of single injection of KA (15 mg/kg body weight). After decapitation of rats, the brain regions were separated and in their homogenates, the concentration of NOx, TBARS and TAS and the activities of NOS, AS, AL, arginase and glutamine synthetase were assayed by colorimetric methods. The results of the study demonstrated the increased activity of NOS and formation of NO in acute and chronic groups epilepsy. The activities of AS and AL were increased and indicate the effective recycling of citrulline to arginine. The activity of glutamine synthetase was decreased in acute and chronic groups of epilepsy compared to control group and indicate the modulation of its activity by NO in epilepsy. The activity of arginase was not changed in acute group; however it was decreased in chronic group and may favor increased production of NO in this condition. The concentration TBARS were increased and TAS decreased in acute and chronic groups of epilepsy and supports the oxidative stress in epilepsy.

Effects of acute ammonia toxicity on nitric oxide (NO), citrulline-NO cycle enzymes, arginase and related metabolites in different regions of rat brain.

Nitric oxide (NO) is involved in many pathophysiological processes in the brain. NO is synthesized from arginine by nitric oxide synthase (NOS) enzymes. Citrulline formed as a by-product of the NOS reaction, can be recycled to arginine by successive actions of argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL) via the citrulline-NO cycle. Hyperammonemia is known to cause poorly understood perturbations of the citrulline-NO cycle. To understand the role of citrulline-NO cycle in hyperammonemia, NOS, ASS, ASL and arginase activities, as well as nitrate/nitrite (NOx), arginine, ornithine, citrulline, glutamine, glutamate and GABA were estimated in cerebral cortex (CC), cerebellum (CB) and brain stem (BS) of rats subjected to acute ammonia toxicity. NOx concentration and NOS activity were found to increase in all the regions of brain in acute ammonia toxicity. The activities of ASS and ASL showed an increasing trend whereas the arginase was not changed. The results of this study clearly demonstrated the increased formation of NO, suggesting the involvement of NO in the pathophysiology of acute ammonia toxicity. The increased activities of ASS and ASL suggest the increased and effective recycling of citrulline to arginine in acute ammonia toxicity, making NO production more effective and contributing to its toxic effects.