Exogenous glutathione exerts a therapeutic effect in ischemic stroke rats by interacting with intrastriatal dopamine.

We previously showed that oral administration of exogenous glutathione (GSH) exerted a direct and/or indirect therapeutic effect on ischemic stroke rats, but the underlying mechanisms remain elusive. In the current study, we conducted a quantitative proteomic analysis to explore the pathways mediating the therapeutic effect of GSH in cerebral ischemia/reperfusion (I/R) model rats. Rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion. The rats were treated with GSH (250 mg/kg, ig) or levodopa (L-dopa, 100 mg/kg, ig) plus carbidopa (10 mg/kg, ig). Neurologic deficits were assessed, and the rats were sacrificed at 24 h after cerebral I/R surgery to measure brain infarct sizes. We conducted a proteomic analysis of the lesion side striatum samples and found that tyrosine metabolism and dopaminergic synapse were involved in the occurrence of cerebral stroke and the therapeutic effect of GSH. Western blot assay revealed that tyrosine hydroxylase (TH) mediated the occurrence of I/R-induced ischemic stroke and the therapeutic effect of GSH. We analyzed the regulation of GSH on endogenous small molecule metabolites and showed that exogenous GSH had the most significant effect on intrastriatal dopamine (DA) in I/R model rats by promoting its synthesis and inhibiting its degradation. To further explore whether DA-related alterations were potential targets of GSH, we investigated the therapeutic effect of DA accumulation on ischemic brain injury. The combined administration of the precursor drugs of DA (L-dopa and carbidopa) significantly ameliorated neurological deficits, reduced infarct size, and oxidative stress, and decreased pro-inflammatory cytokines levels in the striatum of I/R injury rats. More interestingly, exogenous L-dopa/carbidopa could also greatly enhance the exposure of intracerebral GSH by upregulating GSH synthetases and enhancing homocysteine (HCY) levels in the striatum. Thus, administration of exogenous GSH exerts a therapeutic effect on ischemic stroke by increasing intrastriatal DA, and the accumulated DA can, in turn, enhance the exposure of GSH and its related substances, thus promoting the therapeutic effect of GSH.

The impact of third-generation beta-blocker antihypertensive treatment on endothelial function and the prothrombotic state: effects of smoking.

BACKGROUND: The significance of beta-blockers in the treatment of cardiovascular diseases is well established. The effect of vasodilating beta-blockers on endothelial function and prothrombotic state has not been investigated. METHODS: The study comprised 550 consecutive patients with uncomplicated essential hypertension. They were treated with celiprolol, carvedilol or nebivolol monotherapy (171, 179, and 200 patients, respectively), achieving comparable blood pressure reduction. Plasma levels of fibrinogen and homocystine and serum levels of plasminogen activator inhibitor-1 (PAI-1) were obtained before and 6 months after initiation of treatment. RESULTS: The three drugs differentiated in regard to homocystine (P <.00001) and fibrinogen level changes (P =.00003), but not (P = NS) in PAI-1 change. In smokers, differentiation was found in all three parameters (P =.0002, P =.001, and P =.006 for fibrinogen, PAI-1, and homocystine, respectively), but in nonsmokers differentiation was found only in homocystine change (P =.00003). In smokers, fibrinogen, PAI-1, and homocystine were reduced more (P =.002, P =.0009, and P <.0001, respectively) than in nonsmokers in the whole study cohort. The effect of nebivolol was more prominent in smokers than nonsmokers in reducing all three parameters (P =.0001,.003, and.003, respectively), whereas in celiprolol and carvedilol-treated groups, differentiation between smokers and nonsmokers was significant (P =.00003 and.01, respectively) only in homocystine level change. CONCLUSIONS: In hypertensive smokers, nebivolol resulted in a significant decrease of plasma PAI-1, fibrinogen and homocystine. Celiprolol also significantly affected these parameters but to a lesser degree, whereas carvedilol had no significant favorable action. In nonsmokers, homocystine was reduced significantly by nebivolol. We conclude that smoking status should be a determinant of antihypertensive treatment choice.

Hyperhomocysteinemia in Japanese patients with convalescent stage ischemic stroke: effect of combined therapy with folic acid and mecobalamine.

Hyperhomocysteinemia is considered to be a risk factor for vascular diseases including ischemic stroke. It has been shown that plasma homocysteine level can be lowered by folic acid supplementation. Vitamin B(12) may be also beneficial when included in the supplement regimen with folic acid. We have examined in Japanese patients with ischemic stroke the homocysteine-lowering potential of a combination therapy with folic acid and vitamin B(12). Patients with ischemic stroke were randomized into three groups and each group received vitamin B(12) (1500 microg/day, n = 63), folic acid (5 mg/day, n = 64), or both vitamin B(12) and folic acid (n = 64) for 8 weeks. Plasma levels of homocysteine and these vitamins were followed. Significant reduction in plasma homocysteine was observed in all three groups, and the combination therapy yielded the most remarkable result, i.e., plasma total homocysteine was reduced by 38.5% and this was significantly larger than the reduction in other two groups (22.4% and 10.9% in the groups received folic acid and vitamin B(12), respectively). Vitamin B(12) synergizes with folic acid in reducing plasma homocysteine in Japanese patients with ischemic stroke and the combined therapy may be particularly effective in the secondary prevention.

Niacin treatment increases plasma homocyst(e)ine levels.

BACKGROUND: Studies have reported high levels of plasma homocyst(e)ine as an independent risk factor for arterial occlusive disease. The Cholesterol Lowering Atherosclerosis Study reported an increase in plasma homocyst(e)ine levels in patients receiving both colestipol and niacin compared with placebo. Thus the objective of this study was to examine the effect of niacin treatment on plasma homocyst(e)ine levels. METHODS: The Arterial Disease Multiple Intervention Trial, a multicenter randomized, placebo-controlled trial, examined the effect of niacin compared with placebo on homocyst(e)ine in a subset of 52 participants with peripheral arterial disease. RESULTS: During the screening phase, titration of niacin dose from 100 mg to 1000 mg daily resulted in a 17% increase in mean plasma homocyst(e)ine level from 13.1 +/- 4.4 micromol/L to 15.3 +/- 5.6 micromol/L (P <.0001). At 18 weeks after randomization, there was an absolute 55% increase from baseline in mean plasma homocyst(e)ine levels in the niacin group and a 7% decrease in the placebo group (P =.0001). This difference remained statistically significant at the end of follow-up at 48 weeks. CONCLUSIONS: Niacin substantially increased plasma homocyst(e)ine levels, which could potentially reduce the expected benefits of niacin associated with lipoprotein modification. However, plasma homocyst(e)ine levels can be decreased by folic acid supplementation. Thus further studies are needed to determine whether B vitamin supplementation to patients undergoing long-term niacin treatment would be beneficial.

Effects of short-term treatment with metformin on serum concentrations of homocysteine, folate and vitamin B12 in type 2 diabetes mellitus: a randomized, placebo-controlled trial.

OBJECTIVE: Metformin is a key treatment option in type 2 diabetes. However, metformin may decrease vitamin B12 levels and increase levels of homocysteine, a cardiovascular risk factor. We investigated whether 16 weeks of treatment with metformin affects serum concentrations of homocysteine, folate and vitamin B12 in subjects with type 2 diabetes treated with insulin. DESIGN: Placebo-controlled, randomized trial. MEASUREMENTS: at baseline and 16 weeks later. SETTING: This trial was conducted in the outpatient clinics of three general hospitals in The Netherlands. SUBJECTS: A total of 745 patients with type 2 diabetes, treated with insulin and not known with a contraindication for the use of metformin, were approached; 390 gave informed consent and entered the study. Thirty-seven subjects dropped out (12 placebo and 25 metformin users). INTERVENTION: Addition of metformin or placebo to insulin therapy. PRIMARY OUTCOME PARAMETERS: Serum homocysteine, folate, vitamin B12, indices of glycaemic control and body weight. RESULTS: Amongst those who completed 16 weeks of treatment, metformin use, as compared with placebo, was associated with an increase in homocysteine of 4% (0.2 to 8; P=0.039) and with decreases in folate [-7% (-1.4 to -13); P=0.024] and vitamin B12 [-14% (-4.2 to -24); P<0.0001]. In addition, the increase in homocysteine could be explained by the decreases in folate and vitamin B12. CONCLUSION: In patients with type 2 diabetes, 16 weeks of treatment with metformin reduces levels of folate and vitamin B12, which results in a modest increase in homocysteine. The clinical significance of these findings remains to be investigated.