Age-related changes in redox status of rat serum

The Fast-Glycator Phenotype, Skin Advanced Glycation End Products, and Complication Burden Among People With Type 1 Diabetes

OBJECTIVE

Existence of a fast-glycator phenotype among people with type 1 diabetes (T1D) is debated. Routine use of glucose sensors allows the comparison of long-term average glucose levels with laboratory HbA1c values. We herein evaluated whether participants with T1D and HbA1c values higher than their glucose management indicator (GMI) had greater accumulation of advanced glycation end products (AGEs) and chronic complications.

RESEARCH DESIGN AND METHODS

We included participants with T1D using the intermittently scanned continuous glucose monitoring system consecutively for at least 90 days and having a laboratory-determined HbA1c at the end of observation. Skin AGEs were estimated using the skin autofluorescence (SAF) method. The complication burden was assessed by a standardized screening. The fast-glycator phenotype was defined as having a GMI to HbA1c ratio <0.9.

RESULTS

We included 135 individuals with T1D (58% men; mean age, 44.4 years) with a mean diabetes duration of 21 years and a mean HbA1c value of 7.7%. Thirty (22.2%) were defined as having the fast-glycator phenotype. As expected, fast glycators had higher HbA1c (8.6% vs. 7.5%; P < 0.001) with similar 90-day mean glucose level (172 vs. 168 mg/dL; P = 0.52). Fast glycators had higher SAF than did other participants (2.5 vs. 2.1 arbitrary units; P = 0.005) and had a significantly higher prevalence of dyslipidemia (73% vs. 44%; P = 0.005), macroangiopathy (38% vs. 9%; P = 0.001), albuminuria (25% vs. 7%; P = 0.038), and retinopathy (61% vs. 38%; P = 0.022). After adjusting for age and dyslipidemia, the fast-glycator phenotype remained significantly associated with macroangiopathy (odds ratio 3.72; 95% CI 1.22-11.4).

CONCLUSIONS

In T1D, a fast-glycator phenotype defined by the GMI to HbA1c ratio is characterized by elevated skin AGEs and is associated with the complication burden.

Curcumin protects the testis against cadmium-induced histopathological damages and oxidative stress in mice

BACKGROUND

Cadmium is an environmental pollutant which can induce the overproduction of free radicals while suppressing the antioxidant defense system. Curcumin is considered a free-radical scavenger and a potent antioxidant. This study was conducted to investigate the effect of curcumin on serum antioxidant enzymes and histopathological changes in mice treated with cadmium.

METHODS

In this experimental study, adult mice were divided into four groups, namely, control, cadmium chloride (5 mg kg^-1), curcumin (100 mg kg^-1), and curcumin+cadmium chloride. The animals received curcumin 24 h prior to cadmium chloride injection. After 24 h, blood samples were collected and used to assess the levels of malondialdehyde (MDA), antioxidant enzymes activity (catalase, superoxide dismutase, and glutathione peroxidase), total glutathione, total thiol, and hydrogen peroxide. Histopathological evaluation was also performed for testicular tissue.

RESULTS

Mice treated with cadmium showed a significant (p < 0.001) decrease in the activity of antioxidant enzymes, serum amounts of total glutathione and total thiol, and the diameter of seminiferous tubules compared to the control group. This pollutant also significantly (p < 0.001) increased serum levels of MDA and hydrogen peroxide and the lumen diameter of seminiferous tubules compared to the control group. In the curcumin+cadmium group, curcumin significantly (p < 0.001) reversed the adverse effects of cadmium, compared to the cadmium group. In addition, curcumin alone significantly (p < 0.001) increased serum glutathione peroxidase activity and thiol content compared to the control group.

CONCLUSION

Curcumin, as a potent antioxidant, could compensate the adverse effects of cadmium on lipid and protein peroxidation, potentiated serum antioxidant defense system, and ameliorated some morphometrical parameters in the testis of cadmium-treated mice.

The role of glycation in the pathogenesis of aging and its prevention through herbal products and physical exercise

[Purpose]

Advanced glycation end products (AGEs) are non-enzymatic modifications of proteins or lipids after exposure to sugars. In this review, the glycation process and AGEs are introduced, and the harmful effects of AGEs in the aging process are discussed.

[Methods]

Results from human and animal studies examining the mechanisms and effects of AGEs are considered. In addition, publications addressing means to attenuate glycation stress through AGE inhibitors or physical exercise are reviewed.

[Results]

AGEs form in hyperglycemic conditions and/or the natural process of aging. Numerous publications have demonstrated acceleration of the aging process by AGEs. Exogenous AGEs in dietary foods also trigger organ dysfunction and tissue aging. Various herbal supplements or regular physical exercise have beneficial effects on glycemic control and oxidative stress with a consequent reduction of AGE accumulation during aging.

[Conclusion]

The inhibition of AGE formation and accumulation in tissues can lead to an increase in lifespan.

Age associated oxidative damage in lymphocytes

Lymphocytes are an important immunological cell and have been played a significant role in acquired immune system; hence, may play in pivotal role in immunosenescence. Oxidative stress has been reported to increase in elderly subjects, possibly arising from an uncontrolled production of free radicals with aging and decreased antioxidant defenses. This study was aimed to evaluate the level of lipid-protein damage and antioxidant status in lymphocytes of healthy individuals to correlate between oxidative damage with the aging process. Twenty healthy individuals of each age group (11-20; 21-30; 31-40; 41-50; and 51-60 years) were selected randomly. Blood samples were drawn by medical practitioner and lymphocytes were isolated from blood samples. Malondialdehyde (MDA), protein carbonyls (PC) level were evaluated to determine the lipid and protein damage in lymphocytes. Superoxide dismutase (SOD), catalase (CAT), glutathione and glutathione dependent enzymes were estimated to evaluate the antioxidant status in the lymphocytes. Increased MDA and PC levels strongly support the increased oxidative damage in elderly subject than young subjects. The results indicated that, balance of oxidant and antioxidant systems in lymphocytes shifts in favor of accelerated oxidative damage during aging. Thus oxidative stress in lymphocytes may particular interest in aging and may play important role in immunosenescence.

The common variant Q192R at the paraoxonase 1 (PON1) gene and its activity are responsible for a portion of the altered antioxidant status in type 2 diabetes

In this study, we investigated the effects of paraoxonase 1 (PON1) activities and the variant PON1-Q192R on the ferric reducing ability of plasma (FRAP) and total thiol. In addition, we examined the distribution of genotypes of this variant and the relationship of the genotypes with age in patients with type 2 diabetes (T2D). A total of 115 patients with T2D were enrolled in this study. Paraoxonase activity (PON-para) and arylesterase activity (PON-aryl) were determined using spectrophotometric assays. The distribution of the Q192R genotypes was determined by the double substrate method. The antioxidant status was evaluated by determining FRAP and total thiol. The frequencies of Q and R allozyme were 0.78 and 0.22, respectively. The multivariate analysis identified a significant association between the variables PON1-Q192R (Wilks' λ = 0.85, P = 0.002) and PON-aryl (Wilks' λ = 0.896, P = 0.017), with FRAP and total thiol. The significant difference observed for PON1-Q192R and PON-aryl is primarily due to the changes in FRAP levels (η(2 )= 0.127, P = 0.002 for PON1-Q192R; η(2 )= 0.083, P = 0.011 for PON-aryl). The interaction PON1-Q192R-PON-aryl increased the effect sizes from 8 to 19% for FRAP. Only in R-carrying genotypes, there were significant correlations between both PON-para/HDL (r = -0.574, P < 0.001) and PON-aryl/HDL (r = -0.577, P < 0.001) with age. Our data suggest that the variant PON1-Q192R and PON1 activity, particularly PON-aryl, influenced the antioxidant status in T2D. The interaction of this variant and PON1 activity increased the effect size on the antioxidant capacity. Moreover, the presence of the R allozyme may potentiate the effects of age on susceptibility to cardiovascular diseases in T2D.

Selenoprotein H suppresses cellular senescence through genome maintenance and redox regulation

Oxidative stress and persistent DNA damage response contribute to cellular senescence, a degeneration process critically involving ataxia telangiectasia-mutated (ATM) and p53. Selenoprotein H (SelH), a nuclear selenoprotein, is proposed to carry redox and transactivation domains. To determine the role of SelH in genome maintenance, shRNA knockdown was employed in human normal and immortalized cell lines. SelH shRNA MRC-5 diploid fibroblasts under ambient O2 displayed a distinct profile of senescence including β-galactosidase expression, autofluorescence, growth inhibition, and ATM pathway activation. Such senescence phenotypes were alleviated in the presence of ATM kinase inhibitors, by p53 shRNA knockdown, or by maintaining the cells under 3% O2. During the course of 5-day recovery, the induction of phospho-ATM on Ser-1981 and γH2AX by H2O2 treatment (20 μm) subsided in scrambled shRNA but exacerbated in SelH shRNA MRC-5 cells. Results from clonogenic assays demonstrated hypersensitivity of SelH shRNA HeLa cells to paraquat and H2O2, but not to hydroxyurea, neocarzinostatin, or camptothecin. While SelH mRNA expression was induced by H2O2 treatment, SelH-GFP did not mobilize to sites of oxidative DNA damage. The glutathione level was lower in SelH shRNA than scrambled shRNA HeLa cells, and the H2O2-induced cell death was rescued in the presence of N-acetylcysteine, a glutathione precursor. Altogether, SelH protects against cellular senescence to oxidative stress through a genome maintenance pathway involving ATM and p53.

SIRT1 in cardiovascular aging

Cardiovascular disease (CVD) is the leading cause of death worldwide, with aging as the key independent risk factor. Effective interventions are necessary to delay aging. Sirtuin1 (SIRT1), a NAD(+)-dependent histone deacetylase, is closely related to lifespan extension. SIRT1 exerts beneficial effects on aging and age-related diseases, such as atherosclerosis. In this review, we summarize the current knowledge on the functions of SIRT1 in cardiovascular aging, focusing on the underlying molecular mechanisms, including inhibition of oxidative stress and inflammation, and induction of autophagy. We also demonstrate that moderate up-regulation or activation of SIRT1 in cardiovascular aging and age-related CVD may confer important application values.

Dietary nucleotides extend the life span in Sprague-Dawley rats

OBJECTIVE

To observe the effect of prolonged feeding of dietary nucleotides (NTs), and to clarify the effect of NTs on life extension of Sprague-Dawley rats.

METHODS

There were 50 Sprague-Dawley rats in each group (male:female ratio=1:1), which were fed diets supplemented with NTs at concentrations of 0%, 0.01%, 0.04%, 0.16% and 0.64% (wt/wt) from the age of 4 weeks until natural death. We investigated the moribundity and mortality, survival time, spontaneous tumor incidence, and serum oxidative status.

RESULTS

NTs have significantly influence body weight of first 3 month old and food consumption of male rats throughout the life span; it did dose-dependently inhibit the age-related decrease in the activities of antioxidant enzymes and the age-related increase in the levels of lipid peroxidation product in both sexes. NTs notably increased the mean life span, and the maximal life span. Compared to the control group, the incidence of death from tumors was decreased in NTs groups of both sexes.

CONCLUSIONS

Long-term feeding of NTs could dose-dependently increase life span in Sprague-Dawley rats, especially, the tumor-bearing ones. Moreover, the antioxidative property of NTs may be responsible for the increased life span.

Dietary oil modifies the plasma proteome during aging in the rat

Fatty acids and other components of the diet may modulate, among others, mechanisms involved in homeostasis, aging, and age-related diseases. Using a proteomic approach, we have studied how dietary oil affected plasma proteins in young (6 months) or old (24 months) rats fed lifelong with two experimental diets enriched in either sunflower or virgin olive oil. After the depletion of the most abundant proteins, levels of less abundant proteins were studied using two-dimensional electrophoresis and mass spectrometry. Our results showed that compared with the sunflower oil diet, the virgin olive oil diet induced significant decreases of plasma levels of acute phase proteins such as inter-alpha inhibitor H4P heavy chain (at 6 months), hemopexin precursor (at 6 and 24 months), preprohaptoglobin precursor (at 6 and 24 months), and α-2-HS glycoprotein (at 6 and 24 months); antioxidant proteins such as type II peroxiredoxin (at 24 months); proteins related with coagulation such as fibrinogen γ-chain precursor (at 24 months), T-kininogen 1 precursor (at 6 and 24 months), and apolipoprotein H (at 6 and 24 months); or with lipid metabolism and transport such as apolipoprotein E (at 6 and 24 months) and apolipoprotein A-IV (at 24 months). The same diet increased the levels of apolipoprotein A-1 (at 6 and 24 months), diminishing in general the changes that occurred with age. Our unbiased analysis reinforces the beneficial role of a diet rich in virgin olive oil compared with a diet rich in sunflower oil, modulating inflammation, homeostasis, oxidative stress, and cardiovascular risk during aging.

Respiratory control and sternohyoid muscle structure and function in aged male rats: decreased susceptibility to chronic intermittent hypoxia

Obstructive sleep apnoea syndrome (OSAS) is a common respiratory disorder characterized by chronic intermittent hypoxia (CIH). We have shown that CIH causes upper airway muscle dysfunction in the rat due to oxidative stress. Ageing is an independent risk factor for the development of OSAS perhaps due to respiratory muscle remodelling and increased susceptibility to hypoxia. We sought to examine the effects of CIH on breathing and pharyngeal dilator muscle structure and function in aged rats. Aged (18-20 months), male Wistar rats were exposed to alternating cycles of normoxia and hypoxia (90 s each; F(I)O(2)=5% O(2) at nadir) or sham treatment for 8h/day for 9 days. Following CIH exposure, breathing was assessed by whole-body plethysmography. In addition, sternohyoid muscle contractile and endurance properties were examined in vitro. Muscle fibre type and cross-sectional area, and the activity of key oxidative and glycolytic enzymes were determined. CIH had no effect on basal breathing or ventilatory responses to hypoxia or hypercapnia. CIH did not alter succinate dehydrogenase or glycerol phosphate dehydrogenase enzyme activities, myosin heavy chain fibre areal density or cross-sectional area. Sternohyoid muscle force and endurance were unaffected by CIH exposure. Since we have established that this CIH paradigm causes sternohyoid muscle weakness in adult male rats, we conclude that aged rats have decreased susceptibility to CIH-induced stress. We suggest that structural remodelling with improved hypoxic tolerance in upper airway muscles may partly compensate for impaired neural regulation of the upper airway and increased propensity for airway collapse in aged mammals.

Suppression of choroidal neovascularization by N-acetyl-cysteine in mice

PURPOSE

N-acetyl-cysteine (NAC) is a potent antioxidant known to be a precursor of glutathione. The purpose of this study was to investigate the role of NAC in the development of choroidal neovascularization (CNV).

METHODS

CNV was induced in C57BL/6 mice by laser photocoagulation of the ocular fundus. Mice were injected intraperitoneally with NAC or vehicle alone. The levels of 4-hydoroxy-2-nonenal (4-HNE)-modified protein and nucleus factor (NF)-κB were determined by wester blotting. The recruitment of macrophages and neutrophils after laser injury was analyzed immunohistochemically and in myeloperoxidase (MPO) assays. Enzyme-linked immunosorbent assays (ELISA) were used to measure monocyte chemotactic protein (MCP)-1, CXCL1, vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-1, and VEGFR-2. The extent of CNV was evaluated 7 d after laser injury by lectin staining.

RESULTS

In NAC-treated mice with laser-induced injuries, the induction of 4-HNE-modified protein after 3 hr and the activation of NF-κB in nuclear extracts after 6 hr were markedly suppressed compared to vehicle-treated mice. Macrophage and neutrophil recruitment were inhibited and the levels of MCP-1, CXCL1, VEGF, and VEGFR-1 were also lower in NAC-treated mice compared to vehicle-treated mice. Furthermore, the extent of CNV induced was significantly lower in NAC-treated compared to vehicle-treated mice (p = 0.027).

CONCLUSIONS

Our results clearly showed that NAC inhibited indicators of oxidative stress and the activation of NF-κB induced by laser injury, and, consequently, suppressed macrophage and neutrophil infiltration and the development of CNV. This suggests novel preventative and interventional therapeutic strategies for age-related macular degeneration.

Marine collagen peptides prepared from chum salmon (Oncorhynchus keta) skin extend the life span and inhibit spontaneous tumor incidence in Sprague-Dawley Rats

To observe the effects of marine collagen peptides (MCPs) prepared from chum salmon (Oncorhynchus keta) skin on life span and spontaneous tumor incidence, Sprague-Dawley rats were fed diets supplemented with MCP at concentrations of 0%, 2.25%, 4.5%, and 9% (wt/wt) from the age of 4 weeks until natural death. There were 40 rats in each group (male:female ratio = 1:1). The results showed that the MCP did not significantly influence body weight or food consumption of rats of either sex throughout the life span; it did dose-dependently inhibit the age-related decrease in the activities of antioxidant enzymes and the age-related increase in the levels of lipid peroxidation product in both sexes. MCP notably increased the mean life span, the life span of the last 30% of the survivors, and the maximal life span; it decreased overall spontaneous tumor incidence of both sexes with significance in the 4.5% and 9% MCP-treated male groups and 9% MCP-treated female group. Compared to the control group, the incidence of death from tumors was decreased in MCP groups in comparison with the control group of both sexes. Therefore, we concluded that MCPs dose-dependently increase life span and decrease spontaneous tumor incidence in Sprague-Dawley rats. Moreover, the antioxidative property of MCPs may be responsible for the increased life span and protection against tumor development.

Effects of the Chinese prescription Kangen-karyu and its crude drug Tanjin on ageing process in rats

The effects of the Chinese prescription Kangen-karyu and its crude drug Tanjin on the ageing process were investigated in rats. Diets supplemented with Kangen-karyu and Tanjin extracts decreased glycosylated protein levels in serum, a risk marker of ageing and ageing-related diseases. In addition, they inhibited the levels of thiobarbituric acid reactive substance in the serum and liver; Kangen-karyu in particular led to a strong decrease in hepatic mitochondrial thiobarbituric acid reactive substance. The decline in the reduced glutathione/oxidized glutathione ratio in the liver observed with ageing was ameliorated by Kangen-karyu and Tanjin, while these groups attenuated the increase in glutathione peroxidase activity of hepatic tissue against ageing. This suggests that Kangen-karyu and Tanjin regulate the glutathione redox cycle that maintains the cellular redox condition against age-related oxidative stress. Moreover, the overexpression of cytoplasmic cytochrome c observed with ageing was attenuated by Kangen-karyu and Tanjin. This provides new evidence that Kangen-karyu and Tanjin inhibit leakage of superoxide in mitochondria and attenuate cellular oxidative damage. Furthermore, Kangen-karyu and Tanjin would maintain mitochondrial function with ageing through the regulation of related protein expression such as bax and bcl-2 proteins. In addition, Kangen-karyu reduced the expression of nuclear factor kappa B; Kangen-karyu and Tanjin did not affect the expression of inhibitor kappa B. The present study demonstrated that Kangenkaryu prevented oxidative damage and mitochondrial dysfunction with ageing. Furthermore, Kangen-karyu showed a stronger protective effect against ageing by oxidative stress than Tanjin, probably through synergistic and/or additive effects.

Abnormal nitric oxide production in aged rat mesenteric arteries is mediated by NAD(P)H oxidase-derived peroxide

Previous work in our laboratory showed increased basal periarterial nitric oxide (NO) and H2O2 concentrations in the spontaneously hypertensive rat, characterized by oxidant stress, as well as impaired flow-mediated NO production that was corrected by a reduction of periarterial H2O2. Aging is also associated with an increase in vascular reactive oxygen species and results in abnormal vascular function. The current study was designed to assess the role of H2O2 in regulating NO production during vascular aging. In vivo, real-time NO and H2O2 concentrations were measured by microelectrodes in mesenteric arteries of retired breeder (aged; 8-12 mo) and young (2 to 3 mo) Wistar-Kyoto rats under conditions of altered flow. The results in aged rats revealed elevated basal NO (1,611+/-286 vs. 793+/-112 nM, P<0.05) and H2O2 concentrations (16+/-2 vs. 9+/-1 microM, P<0.05) and a flow-mediated increase in H2O2 but not NO production. Pretreatment of aged rats with the antioxidant apocynin lowered both basal H2O2 (8+/-1 microM) and NO (760+/-102 nM) to young levels and restored flow-mediated NO production. Similar results were obtained with the NAD(P)H oxidase inhibitor gp91ds-tat. In addition, acute incubation with topical polyethylene-glycolated catalase lowered the baseline NO concentration and restored flow-mediated NO production. Taken together, the data indicate that elevated baseline and suppressed flow-mediated NO production in aged Wistar-Kyoto rats are mediated by NAD(P)H oxidase-derived H2O2.

Involvement of advanced glycation end products in the pathogenesis of diabetic complications: the protective role of regular physical activity

Advanced glycation end products (AGEs) may play an important role in the pathogenesis of chronic diabetic complications and in the natural process of biological aging. In fact, maintained hyperglycaemia favours the formation of AGEs at the tissue level in diabetic patients, which may influence the triggering of different chronic pathologies of diabetes such as retinopathy, nephropathy, neuropathy and macro- and micro-vascular diseases. Moreover, the literature has also demonstrated the involvement of AGEs in biological aging, which may explain the accelerated process of aging in diabetic patients. The practice of regular physical activity appears to positively influence glycaemic control, particularly in type 2 diabetes mellitus patients. This occurs through the diminution of fasting glycaemia, with a consequent reduction of glycation of plasmatic components suggested by the normalisation of HbA1c plasmatic levels. This exercise-induced positive effect is evident in the blood of diabetic patients and may also reach the endothelium and connective tissues of different organs, such as the kidneys and eyes, and systems, such as the cardiovascular and nervous systems, with a local reduction of AGEs production and further deceleration of organ dysfunction. The aim of this paper was to review the literature concerning this topic to coherently describe the harmful effects of AGEs in organ dysfunction induced by diabetes in advanced age as well as the mechanisms behind the apparent protection given by the practice of regular physical activity.

Proteomic Analysis of Nitrated and 4-Hydroxy-2-Nonenal-Modified Serum Proteins During Aging

Using proteomic techniques, we investigated peroxynitrite (ONOO-) and 4-hydroxy-2-nonenal (HNE) modified serum proteins from young and old Fischer 344 rats. Two-dimensional gel electrophoresis/western blot analysis of nitrotyrosine and HNE-histidine revealed that serum proteins were differentially modified by ONOO- and HNE. Among them, 16 of the modified proteins, identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), are involved in blood coagulation, lipid transport, blood pressure regulation, and protease inhibition. Furthermore, nitration and HNE adduction were found to increase with age, lending support to the oxidative stress hypothesis of aging. Our data showed that proteomic techniques can be valuable tools in the study of protein profiling modifications during aging.

Suppression of oxidative stress in aging NZB/NZW mice: effect of fish oil feeding on hepatic antioxidant status and guanidino compounds

Oxidative stress caused by excessive reactive species (RS) and lipid peroxidation is known to be casually linked to age-related inflammation. To test the hypothesis that fish oil (FO) intake has a beneficial effect on nephritis due to its suppressive action of oxidative stress and the enhancement of antioxidant defenses, we examined the effect of dietary FO on various oxidative stress-related parameters and guanidino compound (GC) levels using (NZB x NZW) F1 (B/W) mice. These mice were fed diets supplemented with either 5% corn oil (control) or 5% FO. At 4 and 9 months of age, the hepatic oxidative status was estimated by assessing RS generation produced from xanthine oxidase, the prostaglandin pathway and lipid peroxidation. To evaluate the effect of FO on redox status, including antioxidant defenses, GSH and GSSG levels and antioxidant enzyme activities were measured. To correlate the extent of oxidative status with the nephritic condition, creatinine, guanidino acetic acid and arginine levels were measured. Results indicated that increased levels of lipid peroxidation, RS generation and xanthine oxidase activity with age were all significantly suppressed by FO feeding. Furthermore, reduced GSH levels, GSH/GSSG ratio and antioxidant enzyme activities in the FO-fed mice were effectively enhanced compared to the corn oil-fed mice. Among several GCs, the age-related increase of creatinine level was blunted by FO. Based on these results, we propose that dietary FO exerts beneficial effects in aged, nephritic mice by suppressing RS, superoxide and lipid peroxidation, and by maintaining a higher GSH/GSSG ratio and antioxidant enzyme activities.

Histamine-3 receptor antagonists reduce superoxide anion generation and lipid peroxidation in rat brain homogenates

Using a cyanide model to induce neurotoxic effects in rat brain homogenates, we examined the neuroprotective properties of three H3 antagonists, namely clobenpropit, thioperamide and impentamine, and compared them to aspirin, a known neuroprotective agent. Superoxide anion levels and malondialdehyde concentration were assessed using the nitroblue tetrazolium and lipid peroxidation assays. Clobenpropit and thioperamide significantly reduced superoxide anion generation and lipid peroxidation. Impentamine reduced lipid peroxidation at all concentrations used, but only reduced superoxide anion generation at a concentration of 1 mM. In the lipid peroxidation assay, all the drugs compared favourably to aspirin. This study demonstrates the potential of these agents to be neuroprotective by exerting antioxidant effects.

Contributions of the sympathetic nervous system, glutathione, body mass and gender to blood pressure increase with normal aging: influence of heredity

Body mass and sympathetic activity increase with aging and might underlie blood pressure (BP) elevation. Increased body mass index (BMI) may elevate BP by increasing sympathetic activity. Glutathione (GSH) can decrease BP, and declines with aging. We measured systolic (SBP) and diastolic BP, BMI, plasma (NE(pl)) and urine norepinephrine (NEu), and plasma GSH in n=204 twins across the age spectrum. BP correlated directly with BMI, NEpl, and NEu, but inversely with GSH. Age correlated with BP, BMI, NEpl, and NEu. BP, BMI, NEpl, and NEu were higher in older subjects than younger subjects, whereas GSH was lower with aging. In older subjects with high (above median) NEpl, SBP was 8 mmHg higher than in those of comparable age with low NE. In younger subjects with high GSH, BP was significantly lower than in younger subjects having low GSH. NEu was significantly reduced in young high-BMI subjects vs young low-BMI subjects. The heritability (h2) of NEpl, NEu, and GSH ranged from approximately 50 to approximately 70%, and these biochemical quantities were considerably more heritable than BP. We conclude that increases in sympathetic activity contribute to aging-induced SBP elevations, especially in older females. GSH reductions apparently participate in aging-induced BP elevations, most strongly in males. BMI increases contribute to BP elevations, particularly in younger subjects. BMI elevations apparently raise BP mainly by peripheral mechanisms, with generally little sympathetic activation. Substantial h(2) for plasma GSH, NE, and urine NE suggests that such traits may be useful 'intermediate phenotypes' in the search for genetic determinants of BP.

Effects of polyunsaturated/saturated fatty acid ratio and antioxidant supplementation on hepatic TBARS and enzyme activities under the maintenance of dietary peroxidizability index value in young and adult rats

AIMS

To investigate the effects of the polyunsaturated/saturated fatty acid (P/S) ratio and antioxidant supplementation on hepatic lipid peroxidation and enzyme activities under the control of the dietary peroxidizability index (PI) value in young and adult rats.

METHODS

We measured thiobarbituric acid-reactive substance (TBARS) concentration and enzyme activities in liver tissue. Female Sprague-Dawley rats aged 3 and 16 weeks were used. Dietary P/S ratios were 0.38 and 4.81 (LP and HP) when the PI value was 81.22. The diets were supplemented with vitamin E 1,000 mg/kg diet and selenium 2.5 mg/kg diet (LPS and HPS).

RESULTS

The hepatic TBARS concentration was higher in LP and LPS than in HP and HPS. In reducing TBARS concentration, antioxidant supplementation was more effective in adult rats than in young rats. Glutathione peroxidase and glutathione-S-transferase activities were lower in young rats than in adult rats.

CONCLUSION

We conclude that dietary fats and antioxidant supplementation play an important role in the change of hepatic TBARS concentration when the dietary PI value is maintained at the same level. However, with the exception of glutathione reductase, no effects of the P/S ratio and antioxidant supplementation on hepatic enzyme activities were detected. This may be due to the invisible effects of fixed PI value in diets.

Age-dependent methamphetamine-induced alterations in vesicular monoamine transporter-2 function: implications for neurotoxicity

Tens of thousands of adolescents and young adults have used illicit methamphetamine. This is of concern since its high-dose administration causes persistent dopaminergic deficits in adult animal models. The effects in adolescents are less studied. In adult rodents, toxic effects of methamphetamine may result partly from aberrant cytosolic dopamine accumulation and subsequent reactive oxygen species formation. The vesicular monoamine transporter-2 (VMAT-2) sequesters cytoplasmic dopamine into synaptic vesicles for storage and perhaps protection against dopamine-associated oxidative consequences. Accordingly, aberrant VMAT-2 function may contribute to the methamphetamine-induced persistent dopaminergic deficits. Hence, this study examined effects of methamphetamine on VMAT-2 in adolescent (postnatal day 40) and young adult (postnatal day 90) rats. Results revealed that high-dose methamphetamine treatment caused greater acute (within 1 h) decreases in vesicular dopamine uptake in postnatal day 90 versus 40 rats, as determined in a nonmembrane-associated subcellular fraction. Greater basal levels of VMAT-2 at postnatal day 90 versus 40 in this purified fraction seemed to contribute to the larger effect. Basal tissue dopamine content was also greater in postnatal day 90 versus 40 rats. In addition, postnatal day 90 rats were more susceptible to methamphetamine-induced persistent dopaminergic deficits as assessed by measuring VMAT-2 activity and dopamine content 7 days after treatment, even if drug doses were adjusted for age-related pharmacokinetic differences. Together, these data demonstrate dynamic changes in VMAT-2 susceptibility to methamphetamine as a function of development. Implications with regard to methamphetamine-induced dopaminergic deficits, as well as dopamine-associated neurodegenerative disorders such as Parkinson's disease, are discussed.

Vascular Aging: Molecular Modulation of the Prostanoid Cascade by Calorie Restriction

The relevance of prostanoids to inflammation, thrombosis, and cardiovascular diseases is well known. The present study attempts to explore age effects on prostanoids and their biosynthesis cascade. Results from comparing prostanoid levels between young (6 months) and old (24 months) Fischer 344 rats showed rises of prostaglandin E2 (PGE2), PGI2, and thromboxane A2 (TXA2) levels in the old rats. Correlating evidence showed gene expression up-regulation of several prostanoid synthase enzymes in old rat aorta. Further, we found that expression of the antioxidant enzyme glutathione peroxidase was raised by age in the aorta, while superoxide dismutase and catalase expression showed no significant change during aging in the aorta. Moreover, calorie restriction (CR) was found to attenuate age-related prostanoid changes by suppressing inflammatory activities. In conclusion, the data from this study indicated that age-related increases in prostanoids and their biosynthesis might be closely associated with a weakened antioxidant capacity.

Modulation of redox-sensitive transcription factors by calorie restriction during aging

Oxidative stress is considered to be a major cause of aging and many age-related diseases. Calorie restriction (CR) is known to retard deleterious, age-related processes. Recent studies document that CR retards the aging process by regulating the redox environment through its anti-oxidative properties. Among the key cellular components exquisitely sensitive to redox status are transcriptions factors such as nuclear factor kappa B (NF-kappaB), activator protein-1 (AP-1), and hypoxia inducible factor-1 (HIF-1). Based on available findings and our recent supporting evidence, we proposed to use a new term, 'molecular inflammation' to emphasize the importance of molecular reaction mechanisms distinct from chronic and fully expressed inflammatory phenomena. Currently, limited information is available on the age-related and dietary modulations of these factors. In this review, we place a major focus on the age effects of NF-kappaB, AP-1, and HIF-1 regulation, and further delineate how age-related changes are modulated by CR. Age-related increases in redox-sensitive NF-kappaB, AP-1, and HIF-1 binding activities are concluded to be associated with increased ROS and CR to modulate their activations by suppressing oxidative stress. Data on cellular regulation provide better molecular insights into the mechanisms underlying cellular redox maintenance, which may be the cross-talk between normal aging and age-associated pathogenic processes.