Folate deficiency is associated with oxidative stress, increased blood pressure, and insulin resistance in spontaneously hypertensive rats

Effect of folic acid supplementation on risk of new-onset diabetes in adults with hypertension in China: Findings from the China Stroke Primary Prevention Trial (CSPPT)

BACKGROUND

The aim of the present post hoc analysis of the China Stroke Primary Prevention Trial (CSPPT) was to evaluate the effect of folic acid supplementation on the risk of new-onset diabetes in hypertensive adults in China.

METHODS

In all, 20 702 hypertensive adults with no history of stroke and/or myocardial infarction (MI) were randomly assigned to receive double-blind daily treatment with tablets containing either: (i) 10 mg enalapril and 0.8 mg folic acid (n = 10 348); or (ii) 10 mg enalapril alone (n = 10 354). New-onset diabetes was defined as either self-reported physician-diagnosed diabetes or the use of glucose-lowering drugs during the follow-up period of the CSPPT.

RESULTS

Over a median treatment duration of 4.5 years, new-onset diabetes occurred in 198 (2.0%) and 214 (2.1%) subjects in the enalapril-folic acid and enalapril groups, respectively (hazard ratio [HR] 0.92; 95% confidence interval [CI] 0.76-1.12). Similar results were observed when analyses were limited to subjects with baseline fasting glucose (FG) <7.0 mmol/L (HR 0.85; 95% CI 0.62-1.14). Furthermore, there was no significant group difference in: (i) the risk of new-onset FG ≥7.0 mmol/L (defined as FG <7.0 at baseline and ≥7.0 mmol/L at the last visit; relative risk [RR] 1.07; 95% CI 0.96-1.20); or (ii) the composite of new-onset diabetes or new-onset FG ≥7.0 mmol/L (RR = 1.06; 95% CI 0.95-1.19).

CONCLUSIONS

Among adults with hypertension with no history of stroke and/or MI in China, folic acid supplementation had no significant effect on the risk of new-onset diabetes.

Effects of long-term folate supplementation on metabolic status and regression of cervical intraepithelial neoplasia: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

This study was conducted to determine the effects of long-term folate supplementation on regression and metabolic status of patients with cervical intraepithelial neoplasia grade 1 (CIN1).

METHODS

This randomized, double-blind, placebo-controlled trial was performed among 58 women diagnosed with CIN1, ages 18 to 55 y old. Participants were randomly divided into two groups to receive 5 mg/d folate supplements (n = 29) or placebo (n = 29) for 6 mo. Fasting blood samples were taken at baseline and 6 mo after intervention to quantify related markers.

RESULTS

A greater percentage of women in the folate group had regressed CIN1 (83.3 versus 52.0%, P = 0.019) than those in the placebo group. Long-term folate supplementation resulted in a significant decrease in serum insulin levels (-1.6 ± 6.2 versus +2.6 ± 6.9 μIU/mL, P = 0.018) and homeostatic model assessment-beta cell function (HOMA-B) (-13.0 ± 39.0 versus +11.2 ± 42.3, P = 0.028) compared with the placebo. Additionally, plasma glutathione (GSH) levels were significantly increased (+81.5 ± 264.1 versus -220.9 ± 342.5 μmol/L, P < 0.001) and malondialdehyde (MDA) levels were significantly reduced (-1.0 ± 1.1 versus +0.1 ± 1.6 μmol/L, P = 0.004) in the folate group compared to the placebo.

CONCLUSIONS

Taken together, folate supplementation (5 mg/d) for 6 mo among women with CIN1 resulted in its regression as well as led to decreased serum insulin, HOMA-B, plasma MDA and increased plasma GSH levels; however, it did not affect other metabolic profiles.

Adropin is associated with hyperhomocysteine and coronary atherosclerosis

Homocysteine has been recognized as a risk factor for atherosclerosis and cardiovascular diseases. Adropin is a newly-identified energy homeostasis protein with a potential protective effect against coronary artery disease (CAD). This study attempted to measure the correlation between serum homocysteine and adropin levels in patients with CAD, and to ascertain how the two hormones could affect the severity of coronary atherosclerosis. A cohort of CAD patients who had undergone coronary angiography was prospectively recruited. The serum homocysteine and adropin levels of the patients were measured and the severity of coronary atherosclerosis was quantified with the SYNTAX score. The data were analyzed with a generalized structural equation model. In total, 170 consecutive patients were recruited with a mean serum homocysteine level of 15.9±8.3 µmol/l, and 76 (44.7%) patients were identified as hyperhomocysteinemic with a serum homocysteine level >15 µmol/l. Serum homocysteine level was found to be significantly negatively correlated with serum adropin level (r=-0.169, P=0.028). Patients with hyperhomocysteinemia had lower serum adropin levels and higher SYNTAX scores than patients without hyperhomocysteinemia. Further analysis with a generalized structural equation model showed that adropin was significantly associated with hyperhomocysteinemia (adjusted odds ratio: 0.95, 95% confidence interval: 0.93 to 0.98; P=0.002), which in turn was significantly associated with the SYNTAX score (coefficient: 4.71, 95% confidence interval: 1.39 to 8.03; P=0.005). In conclusion, the serum homocysteine level was inversely correlated with the serum adropin level in patients with CAD. A low serum adropin level was associated with hyperhomocysteinemia and more severe coronary atherosclerosis, as reflected by a higher SYNTAX score.

Modulation of Hypercholesterolemia-Induced Oxidative/Nitrative Stress in the Heart

Hypercholesterolemia is a frequent metabolic disorder associated with increased risk for cardiovascular morbidity and mortality. In addition to its well-known proatherogenic effect, hypercholesterolemia may exert direct effects on the myocardium resulting in contractile dysfunction, aggravated ischemia/reperfusion injury, and diminished stress adaptation. Both preclinical and clinical studies suggested that elevated oxidative and/or nitrative stress plays a key role in cardiac complications induced by hypercholesterolemia. Therefore, modulation of hypercholesterolemia-induced myocardial oxidative/nitrative stress is a feasible approach to prevent or treat deleterious cardiac consequences. In this review, we discuss the effects of various pharmaceuticals, nutraceuticals, some novel potential pharmacological approaches, and physical exercise on hypercholesterolemia-induced oxidative/nitrative stress and subsequent cardiac dysfunction as well as impaired ischemic stress adaptation of the heart in hypercholesterolemia.

Tetramethylpyrazine identified by a network pharmacology approach ameliorates methotrexate-induced oxidative organ injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tetramethylpyrazine (TMP) is one of the active constituents extracted from a frequently used herb, Ligusticum wallichii Franchat (Chuan-Xiong in Chinese), in traditional Chinese medicine. TMP can exert multiple pharmacological actions such as anti-inflammatory, anti-oxidative damage, anti-platelet and neuroprotective effects, and its applications deserve further explored.

AIM OF THE STUDY

This study aimed to determine the new role of TMP identified by a network pharmacology approach to alleviate the methotrexate (MTX)-induced oxidative injury and characterize their mechanism of combinational actions.

MATERIALS AND METHODS

A network pharmacology-based screening strategy is applied for target profile prediction and pharmacological characterization of herbal compounds, which is used to guide the following in vitro and in vivo experiments. The effect of herbal compounds identified by network pharmacology approaches to reduce the toxicity of MTX was assessed by MTX-induced rat toxicity model. The potential targets of TMP in this study were evaluated using standard protocols provided by Cerep, Inc.

RESULTS

This strategy identified TMP from Ligusticum wallichii Franchat as a potent compound for ameliorating the oxidative organ injury of MTX. According to the predicted target profiles of TMP, a possible mechanism of the abrogation of MTX-induced toxicity is that TMP could upregulate cAMP by inhibiting phosphodiesterase (PDE) 10A2 activity. Another novel finding is that the competitive binding and antagonistic effects of TMP on adenosine receptor 2A and 2B appear to play important roles in the TMP-mediated reversal of MTX-induced hepatic injury.

CONCLUSION

TMP identified by a network pharmacology approach could ameliorate MTX-induced oxidative organ injury. This study provides important evidence for the preclinical evaluation of TMP and MTX as a novel combinatorial remedy.

Diabetic Cardiovascular Disease Induced by Oxidative Stress

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus (DM). DM can lead to multiple cardiovascular complications, including coronary artery disease (CAD), cardiac hypertrophy, and heart failure (HF). HF represents one of the most common causes of death in patients with DM and results from DM-induced CAD and diabetic cardiomyopathy. Oxidative stress is closely associated with the pathogenesis of DM and results from overproduction of reactive oxygen species (ROS). ROS overproduction is associated with hyperglycemia and metabolic disorders, such as impaired antioxidant function in conjunction with impaired antioxidant activity. Long-term exposure to oxidative stress in DM induces chronic inflammation and fibrosis in a range of tissues, leading to formation and progression of disease states in these tissues. Indeed, markers for oxidative stress are overexpressed in patients with DM, suggesting that increased ROS may be primarily responsible for the development of diabetic complications. Therefore, an understanding of the pathophysiological mechanisms mediated by oxidative stress is crucial to the prevention and treatment of diabetes-induced CVD. The current review focuses on the relationship between diabetes-induced CVD and oxidative stress, while highlighting the latest insights into this relationship from findings on diabetic heart and vascular disease.

Joint associations of folate, homocysteine and MTHFR, MTR and MTRR gene polymorphisms with dyslipidemia in a Chinese hypertensive population: a cross-sectional study

BACKGROUND

Dyslipidemia is a well-established risk factor for cardiovascular disease. Serum lipids were affected by several gene polymorphisms, folate, homocysteine and other metabolite levels. We aim to investigate the effects of homocysteine metabolism enzyme polymorphisms (MTHTR C677T, MTHFR A1298C, MTR A2756G and MTRR A66G) and their interactions with folate, homocysteine on serum lipid levels in Chinese patients with hypertension.

METHODS

Participants were 480 hypertensive adults that enrolled in September to December 2005 from six different Chinese hospitals (Harbin, Shanghai, Shenyang, Beijing, Xi'an, and Nanjing). Known MTHFR C677T, MTHFR A1298C, MTR A2756G and MTRR A66G genotypes were determined by PCR-RFLP methods. Serum folate was measured by chemiluminescent immunoassay, homocysteine was measured by high-performance liquid chromatography, serum lipids parameters were determined by an automatic biochemistry analyzer, low-density lipoprotein was calculated by Friedewald's equation. Unitary linear regression model was used to assess the associations of gene polymorphisms, folate and homocysteine on serum lipid profiles. Unconditional logistic regression model was applied to test the interactions of folate, homocysteine and gene polymorphisms on dyslipidemia.

RESULTS

No correlations between gene polymorphisms and homocysteine on serum lipid profiles. Compared with normal folate patients, patients with low folate showed higher odds of hypertriglyceridemia (OR = 2.02, 95 % CI: 1.25-3.25, P = 0.004) and low levels of high-density lipoprotein cholesterol (OR = 1.88, 95 % CI: 1.07-3.28, P = 0.027). Each of four gene polymorphisms (MTHTR C677T, MTHFR A1298C, MTR A2756G and MTRR A66G) combined with low folate showed higher odds of hypertriglyceridemia (P for trend: 0.049, 0.004, 0.007 and 0.005, respectively). MTHFR C677T and A1298C with low folate showed higher odds of low levels of high-density lipoprotein cholesterol (P for trend: 0.008 and 0.031).

CONCLUSIONS

Low folate status and homocysteine metabolism gene polymorphisms (MTHTR C677T, MTHFR A1298C, MTR A2756G and MTRR A66G) may have a synergistic effect increased the incidence of dyslipidemia in Chinese hypertensive population.

Reduction of oxidative stress by an ethanolic extract of leaves of Piper betle (Paan) Linn. decreased methotrexate-induced toxicity

Methotrexate (MTX), a folate antagonist, is currently used as first line therapy for autoimmune diseases like rheumatoid arthritis and psoriasis, but its use is limited by the associated hepatotoxicity. As leaves of Piper betle, belonging to family Piperaceae, have antioxidant and anti-inflammatory properties, the present study was undertaken to investigate the potential of Piper betle leaf extract (PB) in attenuating MTX-induced hepatotoxicity. Rats pre-treated with PB (50 or 100 mg kg(-1) b.w., p.o.) were administered with a single dose of MTX (20 mg kg(-1), b.w., i.p.) and its hepatoprotective efficacy was compared with folic acid (1 mg kg(-1) b.w., i.p.), conventionally used to minimize MTX-induced toxicity. MTX-induced hepatotoxicity was confirmed by increased activities of marker enzymes, alanine transaminase, aspartate transaminase, and alkaline phosphatase which were remitted by pre-treatment with PB and corroborated with histopathology. Additionally, MTX-induced hepatic oxidative stress which included increased generation of reactive oxygen species, enhanced lipid peroxidation, depleted levels of glutathione and decreased activities of antioxidant enzymes was effectively mitigated by PB, indicative that its promising antioxidant-mediated hepatoprotective activity was worthy of future pharmacological consideration.

Homocysteine Metabolism Gene Polymorphisms (MTHFR C677T, MTHFR A1298C, MTR A2756G and MTRR A66G) Jointly Elevate the Risk of Folate Deficiency

Folate deficiency is strongly associated with cardiovascular disease. We aimed to explore the joint effect of the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, methionine synthase (MTR) A2756G, and methionine synthase reductase (MTRR) A66G polymorphisms on folate deficiency in a Chinese hypertensive population. A total of 480 subjects aged 28–75 were enrolled in this study from September 2005–December 2005 from six hospitals in different Chinese regions. Known genotypes were detected by PCR-RFLP methods and serum folate was measured by chemiluminescence immunoassay. Our results showed that MTHFR 677TT and MTR 2756AG + GG were independently associated with a higher risk of folate deficiency (TT vs. CC + CT, p < 0.001 and AG + GG vs. AA p = 0.030, respectively). However, the MTHFR A1298C mutation may confer protection by elevating the serum folate level (p = 0.025). Furthermore, patients carrying two or more risk genotypes showed higher odds of folate deficiency than null risk genotype carriers, especially those carrying four risk genotypes. These findings were verified by generalized multifactor dimensionality reduction (p = 0.0107) and a cumulative effects model (p = 0.001). The results of this study have shown that interactions among homocysteine metabolism gene polymorphisms lead to dramatic elevations in the folate deficiency risk.

Metformin prevents ischemia reperfusion-induced oxidative stress in the fatty liver by attenuation of reactive oxygen species formation

Nonalcoholic fatty liver disease is associated with chronic oxidative stress. In our study, we explored the antioxidant effect of antidiabetic metformin on chronic [high-fat diet (HFD)-induced] and acute oxidative stress induced by short-term warm partial ischemia-reperfusion (I/R) or on a combination of both in the liver. Wistar rats were fed a standard diet (SD) or HFD for 10 wk, half of them being administered metformin (150 mg·kg body wt(-1)·day(-1)). Metformin treatment prevented acute stress-induced necroinflammatory reaction, reduced alanine aminotransferase and aspartate aminotransferase serum activity, and diminished lipoperoxidation. The effect was more pronounced in the HFD than in the SD group. The metformin-treated groups exhibited less severe mitochondrial damage (markers: cytochrome c release, citrate synthase activity, mtDNA copy number, mitochondrial respiration) and apoptosis (caspase 9 and caspase 3 activation). Metformin-treated HFD-fed rats subjected to I/R exhibited increased antioxidant enzyme activity as well as attenuated mitochondrial respiratory capacity and ATP resynthesis. The exposure to I/R significantly increased NADH- and succinate-related reactive oxygen species (ROS) mitochondrial production in vitro. The effect of I/R was significantly alleviated by previous metformin treatment. Metformin downregulated the I/R-induced expression of proinflammatory (TNF-α, TLR4, IL-1β, Ccr2) and infiltrating monocyte (Ly6c) and macrophage (CD11b) markers. Our data indicate that metformin reduces mitochondrial performance but concomitantly protects the liver from I/R-induced injury. We propose that the beneficial effect of metformin action is based on a combination of three contributory mechanisms: increased antioxidant enzyme activity, lower mitochondrial ROS production, and reduction of postischemic inflammation.

Erectile dysfunction drugs and oxidative stress in the liver of male rats

Erectile dysfunction (ED) affected the lives of more than 300 million men worldwide. Erectile dysfunction drugs (EDD), known as phosphodiesterase inhibitors (PDEIs), have been used for treatment of ED. It has been shown that oxidative stress plays an important role in the progression of erectile dysfunction. Oxidative stress can be alleviated or decreased by antioxidant enzymes. Therefore, the present study aims at investigating the changes in the activity of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione reductase as well as protein expression of glutathione peroxidase and glutathione S-transferase after treatment of male rats with a daily dose of sildenafil (1.48 mg/kg), tadalafil (0.285 mg/kg) and vardenafil (0.285 mg/kg) for three weeks. In addition, levels of reduced glutathione and malondialdyhyde (MDA) were assayed. The present study showed that sildenafil, vardenafil, and tadalafil treatments significantly decreased the levels of glutathione, MDA and the activity of glutathione reductase. In addition, vardenafil and sildenafil increased the activity of superoxide dismutase and catalase. Interestingly, western immunoblotting data showed that vardenafil induced the activity of glutathione peroxidase (GP_X) and its protein expression, whereas tadalafil and sildenafil inhibited such enzyme activity and its protein expression. In addition, the protein expression of GST π isozyme was markedly reduced after treatment of rats with sildenafil. It is concluded that ED drugs induced the activities of both SOD and catalase which consequently decreased MDA level. Therefore, decrement in MDA levels could increase nitric oxide–cGMP level which in turn promotes the erection mechanism.

Markers of macromolecular oxidative damage in maternal serum and risk of neural tube defects in offspring

Neural tube defects (NTDs) are among the most common and severe congenital malformations. To examine the association between markers of macromolecular oxidative damage and risk of NTDs, we measured levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), protein carbonyl (PC), and 8-iso-prostaglandin F2α (8-iso-PGF2α) in maternal serum samples of 117 women with NTD-affected pregnancies and 121 women with healthy term newborns. We found higher levels of 8-OHdG and PC in the NTD group than in the control group; however, we did not observe a statistically significant difference in 8-iso-PGF2α levels between the NTD and the control groups. NTD risk increased with increasing quartiles of 8-OHdG [odds ratio (OR)=1.17; 95% confidence interval (CI) 0.39-3.51; OR=2.19; 95% CI, 0.68-7.01; OR=3.70; 95% CI, 1.30-10.51, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.009], and with increasing quartiles of PC (OR=2.26; 95% CI, 0.66-7.69; OR=3.86; 95% CI, 1.17-12.80; OR=5.98; 95% CI, 1.82-19.66, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.002]. Serum levels of 8-OHdG were higher in women who did not take folic acid supplements during the periconceptional period. These results suggest that oxidative stress is present in women carrying pregnancies affected by NTDs.

Nebivolol to attenuate the effects of hyper-homocysteinaemia in rats

OBJECTIVE

This study investigated the prophylactic effect of nebivolol against hyper-homocysteinaemia (hHcy) induced oxidative stress in brain, heart, liver and kidney tissues and histomorphometric changes in the thoracic aorta.

METHODS

Twenty-four adult male Wistar rats were divided into a control, nebivolol, hHcy and nebivolol+hHcy group. hHcy was induced by oral administration of L-methionine (1 g/kg/day) for 28 days. 10 mg/kg/day nebivolol was administered orally for 28 days. Malondialdehyde (MDA) and glutathione (GSH) levels and catalase (CAT) and superoxide dismutase (SOD) activities in the tissues were determined. The total cross-sectional area (TCSA), luminal cross-sectional area (LCSA) and intima-media thickness (IMT) were measured in the thoracic aorta.

RESULTS

Homocysteine (Hcy) levels were lower in the nebivolol+hHcy group than in the hHcy group. Nebivolol treatment significantly decreased high MDA levels in the brain, heart and liver tissues. The level of GSH was higher in the brain, heart and kidney tissues of the nebivolol+hHcy group (P<0.001). The activity of CAT increased only in the kidney tissue of the nebivolol+hHcy group (P<0.01), and the activity of SOD was significantly increased in all the tissues in this group. Increased TCSA and IMT in the nebivolol+hHcy group were significantly decreased after nebivolol administration. The LCSA was significantly higher in the hHcy group than the control group, probably due to outward vascular remodelling.

CONCLUSION

Nebivolol treatment may be useful in different clinical scenarios where hHcy affects physiopathological pathways.

Folate administration decreases oxidative status and blood pressure in postmenopausal women

PURPOSE

The purpose of this study was to evaluate whether folate exerts antioxidant effects in postmenopausal women and whether this effect is related to folate-induced modification of 24-h ambulatory blood pressure (BP).

METHODS

Double-blind placebo-controlled study performed in 30 apparently healthy postmenopausal women recruited at the outpatient service of University Hospital. Women, free from hormones or substances possibly interfering with the investigated parameters, were randomized to receive orally for 3 weeks placebo (n = 15) or 15 mg/day of 5-methyltetrahydrofolate (5-MTHF; n = 15). Whole-blood free oxygen radicals test (FORT), free oxygen radical defence (FORD), lipids, glucose, insulin, insulin resistance [homeostatic model assessment for insulin resistance (HOMA-IR)], homocysteine and 24-h ambulatory BP values were evaluated.

RESULTS

In the entire group of women, FORT was independently and inversely related to the day-night difference of diastolic (r = 0.420; p = 0.03) and mean BP (r = 0.497; p = 0.01). Placebo did not affect any biochemical or BP parameter. 5-MTHF reduced FORT (-71.5 ± 98.2; p = 0.02) and increased FORD (0.5 ± 0.9; p = 0.05), decreased insulin (p = 0.01), HOMA-IR (p = 0.0002) and homocysteine (p = 0.008). During 5-MTHF, night-time mean (p = 0.001) and diastolic BP (p = 0.002) decreased of about 5 mmHg and the day-night difference of mean (p = 0.001) and diastolic BP (p = 0.002) contemporaneously increased. FORT reduction was related to the amplification of the nocturnal decline of mean (0.697; p = 0.006) and diastolic BP (r = 0.777; p = 0.002) and to the amplification of the day-night difference of diastolic BP (r = 0.63; p = 0.015).

CONCLUSIONS

Present data show a clear reduction of oxidative stress during 5-MTHF administration and a strong correlation between this decrease and the nocturnal decline of BP. The possible link between the two is worthy to be explored.

Recent Progress in the Genetics of Spontaneously Hypertensive Rats

The spontaneously hypertensive rat (SHR) is the most widely used animal model of essential hypertension and accompanying metabolic disturbances. Recent advances in sequencing of genomes of BN-Lx and SHR progenitors of the BXH/HXB recombinant inbred (RI) strains as well as accumulation of multiple data sets of intermediary phenotypes in the RI strains, including mRNA and microRNA abundance, quantitative metabolomics, proteomics, methylomics or histone modifications, will make it possible to systematically search for genetic variants involved in regulation of gene expression and in the etiology of complex pathophysiological traits. New advances in manipulation of the rat genome, including efficient transgenesis and gene targeting, will enable in vivo functional analyses of selected candidate genes to identify QTL at the molecular level or to provide insight into mechanisms whereby targeted genes affect pathophysiological traits in the SHR.

Neuroprotective effects of folic acid on experimental diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is widely considered as a degenerative complication of diabetic patients. The clinical effectiveness of folic acid (FA) on DPN is uncertain. The objective of the present study was to determine the effect of FA in DPN using electromyography (EMG), histopathological examination, immunohistochemistry, inclined plane test, and malondialdehyde (MDA) levels as a marker for lipid peroxidation in experimental diabetic rats. A total of 21 Sprague Dawley rats were randomly divided into 3 groups: control group, diabetes group, and FA-treated group. In EMG, compound muscle action potential (CMAP) amplitude in the sciatic nerve was lower in the diabetes group compared with the control group. CMAP amplitude in the sciatic nerve was higher in the FA-treated group when compared with the diabetes group. Distal latency and CMAP duration in the sciatic nerve were lower in the FA-treated group when compared with the diabetes group. In histopathological examination of the sciatic nerve, peripheral fibrosis was present in the diabetic group; the fibrosis was lower in the FA-treated group. In comparison with the diabetes group, the expression of nerve growth factor (NGF) was higher in the FA-treated group. The scores for the inclined plane test were lower in the diabetes group and higher in the FA-treated group than the control group. The MDA levels were significantly lower in the FA-treated group when compared with the diabetes group.

The study suggests that FA can protect diabetic rats against DPN and that the underlying mechanism for this may be related to improvement of the expression of NGF and lower MDA levels.

Moderate hyperhomocysteinemia provokes dysfunction of cardiovascular autonomic system and liver oxidative stress in rats

Hyperhomocysteinemia (HHcy) is associated with cardiovascular disease, atherosclerosis and reactive oxygen species generation. Thus, our aim was to investigate whether there was an association between HHcy, blood pressure, autonomic control and liver oxidative stress. Male Wistar rats were divided into 2 groups and treated for 8weeks: one group (control, CO) received tap water, while the other group (methionine, ME) was given a 100mg/kg of methionine in water by gavage. Two catheters were implanted into the femoral artery and vein to record arterial pressure (AP) and heart rate (HR) and drug administration. Signals were recorded by a data acquisition system. Baroreflex sensitivity was evaluated by HR responses to AP changes induced by vasoactive drugs. HR variability and AP variability were performed by spectral analysis in time and frequency domains to evaluate the contribution of the sympathetic and parasympathetic modulation. Lipid peroxidation and antioxidant enzyme activities were evaluated by measuring superoxide dismutase, catalase and glutathione peroxidase in liver homogenates. The ME group presented a significant increase in systolic arterial pressure (118±9 vs 135±6mmHg), diastolic arterial pressure (81±6 vs. 92±4) and mean arterial pressure (95±7 vs. 106±6). In addition, pulse interval variability presented a significant decrease (41%), while the low frequency component of AP was significantly increased (delta P=6.24mmHg(2)) in the ME group. We also found a positive association between lipid peroxidation and cardiac sympathetic modulation, sympathetic and vagal modulation ratio and systolic pressure variability. Collectively, these findings showed that HHcy induced dysfunction of cardiovascular autonomic system and liver oxidative stress.