Aging influences multiple indices of oxidative stress in the heart of the Fischer 344/NNia x Brown Norway/BiNia rat

Age-related alteration in HNE elimination enzymes

4-hydroxynonenal (HNE, 4-hydroxy-2-nonenal) is a primary α,β-unsaturated aldehyde product of lipid peroxidation. The accumulation of HNE increases with aging and the mechanisms are mainly attributable to increased oxidative stress and decreased capacity of HNE elimination. In this review article, we summarize the studies on age-related change of HNE concentration and alteration of HNE metabolizing enzymes (GCL, GST, ALDHs, aldose reductase, and 20S-proteasome), and discuss potential mechanism of age-related decrease in HNE-elimination capacity by focusing on Nrf2 redox signaling.

Dietary resveratrol confers apoptotic resistance to oxidative stress in myoblasts

High levels of reactive oxygen species (ROS) contribute to muscle cell death in aging and disuse. We have previously found that resveratrol can reduce oxidative stress in response to aging and hindlimb unloading in rodents in vivo, but it was not known if resveratrol would protect muscle stem cells during repair or regeneration when oxidative stress is high. To test the protective role of resveratrol on muscle stem cells directly, we treated the C2C12 mouse myoblast cell line with moderate (100 μM) or very high (1 mM) levels of H2O2 in the presence or absence of resveratrol. The p21 promoter activity declined in myoblasts in response to high ROS, and this was accompanied a greater nuclear to cytoplasmic translocation of p21 in a dose-dependent matter in myoblasts as compared to myotubes. Apoptosis, as indicated by TdT-mediated dUTP nick-end labeling, was greater in C2C12 myoblasts as compared to myotubes (P<.05) after treatment with H2O2. Caspase-9, -8 and -3 activities were elevated significantly (P<.05) in myoblasts treated with H2O2. Myoblasts were more susceptible to ROS-induced oxidative stress than myotubes. We treated C2C12 myoblasts with 50 μM of resveratrol for periods up to 48 h to determine if myoblasts could be rescued from high-ROS-induced apoptosis by resveratrol. Resveratrol reduced the apoptotic index and significantly reduced the ROS-induced caspase-9, -8 and -3 activity in myoblasts. Furthermore, Bcl-2 and the Bax/Bcl-2 ratio were partially rescued in myoblasts by resveratrol treatment. Similarly, muscle stem cells isolated from mouse skeletal muscles showed reduced Sirt1 protein abundance with H2O2 treatment, but this could be reversed by resveratrol. Reduced apoptotic susceptibility in myoblasts as compared to myotubes to ROS is regulated, at least in part, by enhanced p21 promoter activity and nuclear p21 location in myotubes. Resveratrol confers further protection against ROS by improving Sirt1 levels and increasing antioxidant production, which reduces mitochondrial associated apoptotic signaling, and cell death in myoblasts.

Pro-apoptotic effects of lipid oxidation products: HNE at the crossroads of NF-κB pathway and anti-apoptotic Bcl-2

The axis between lipid oxidation products and cell death is explicitly linked. 4-Hydroxynonenal (HNE), as well as other lipid oxidation products was also established to induce apoptosis in various experimental settings. Yet, the decision leading to apoptotic execution not only includes upregulation of pro-apoptotic signals but also involves a downregulation of anti-apoptotic signals. Within the frames of this paradigm, HNE acts significantly different from other lipid oxidation products in the regulation of two widely known anti-apoptotic elements, Nuclear Factor-κB (NF-κB) transcription factors and its target anti-apoptotic B-Cell Lymphoma-2 (Bcl-2) protein. Even so, a review inclusively linking these anti-apoptotic factors and their crosstalk upon HNE exposure is still at demand. In order to elucidate presence of such crosstalk, reports on the link between HNE and NF-κB pathway, on the link between HNE and anti-apoptotic Bcl-2 and on the crossroad of these links during HNE exposure were summarized and discussed. IKK, the upstream kinase of NF-κB, has been shown to regulate HNE mediated phosphorylation and inactivation of Bcl-2 by our group. Based on this observation and other studies reporting on HNE-NF-κB pathway interaction, IKK was proposed to mediate the crosstalk of NF-κB pathway and anti-apoptotic Bcl-2 protein, when HNE is present. These reports further suggested that HNE based inhibition of NF-κB pathway is highly likely. Besides, evidence on the HNE-anti-apoptotic Bcl-2 axis supported the deduction of HNE mediated NF-κB pathway inhibition and IKK mediated Bcl-2 inactivation. In conclusion, through combining all evidences, three possible scenarios intervening the HNE mediated crosstalk between NF-κB pathway and anti-apoptotic Bcl-2 protein, was extrapolated.

4-hydroxynonenal-mediated signaling and aging

4-Hydroxy-2-nonenal (HNE), one of the major α, β-unsaturated aldehydes produced during lipid peroxidation, is a potent messenger in mediating signaling pathways. Lipid peroxidation and HNE production appear to increase with aging. Although the cause and effect relation remains arguable, aging is associated with significant changes in diverse signaling events, characterized by enhanced or diminished responses of specific signaling pathways. In this review we will discuss how HNE may contribute to aging-related alterations of signaling pathways.

Smoking modify the effects of polycyclic aromatic hydrocarbons exposure on oxidative damage to DNA in coke oven workers

PURPOSE

Coke oven emissions containing polycyclic aromatic hydrocarbons (PAHs) are predominant toxic constituents of particulate air pollution that have been linked to increased risk of lung cancer. Numerous epidemiological studies have suggested that oxidative DNA damage may play a pivotal role in the carcinogenic mechanism of lung cancer. Little is known about the effect of interaction between PAHs exposure and lifestyle on DNA oxidative damage.

METHODS

The study population is composed by coke oven workers (365) and water treatment workers (144), and their urinary levels of four PAH metabolites and 8-hydroxydeoxyguanosine (8-OHdG) were determined. Airborne samples of exposed sites (4) and control sites (3) were collected, and eight carcinogenic PAHs were detected by high-performance liquid chromatography.

RESULTS

The median values of the sum of eight carcinogenic PAHs and BaP in exposed sites were significantly higher than control sites (P < 0.01). The study found that the urinary PAH metabolites were significantly elevated in coke oven workers (P < 0.01). Multivariate logistic regression analysis revealed that the risk of high levels of urinary 8-OHdG will increase with increasing age, cigarette consumption, and levels of urinary 1-hydroxypyrene, and P for trend were all <0.05. Smoking can significantly modify the effects of urinary 1-hydroxypyrene on high concentrations urinary 8-OHdG, during co-exposure to both light or heavy smoking and high 1-hydroxypyrene levels (OR 4.28, 95% CI 1.32-13.86 and OR 5.05, 95% CI 1.63-15.67, respectively).

CONCLUSIONS

Our findings quantitatively demonstrate that workers exposed to coke oven fumes and smoking will cause more serious DNA oxidative damage.

Efficacy of female rat models in translational cardiovascular aging research

Cardiovascular disease is the leading cause of death in women in the United States. Aging is a primary risk factor for the development of cardiovascular disease as well as cardiovascular-related morbidity and mortality. Aging is a universal process that all humans undergo; however, research in aging is limited by cost and time constraints. Therefore, most research in aging has been done in primates and rodents; however it is unknown how well the effects of aging in rat models translate into humans. To compound the complication of aging gender has also been indicated as a risk factor for various cardiovascular diseases. This review addresses the systemic pathophysiology of the cardiovascular system associated with aging and gender for aging research with regard to the applicability of rat derived data for translational application to human aging.

The Effects of Aging on Indices of Oxidative Stress and Apoptosis in the Female Fischer 344/Nnia X Brown Norway/BiNia Rat Heart

Oxidative-nitrosative stress may play a role in age-associated cardiovascular disease as implied by recent studies.However, limited research has been conducted using aged female rodent models. In this study, we examined hearts obtained from 6-, 26-, and 30-month old female Fischer 344/Nnia x Brown Norway/BiNia (F344xBN) rats in order to examine how aging affects levels of cardiac oxidative-nitrosative stress and apoptosis. Oxidative (superoxide anion and 4-HNE) and nitrosative (protein nitrosylation) stress markers were increased 180 ± 17 %, 110 ± 3 %, and 14 ± 2 %, respectively in 30-month hearts compared to the hearts of 6-month female rats. Coincident with these changes in oxidative-nitrosative stress, aging was also found to be associated with increases in the number of Tdt-mediated dUTP nick labeling (TUNEL)-positive cardiomyocytes, alterations in the Bax/Bcl-2 ratio, and elevated cleavage of caspase-3. Regression analysis demonstrates significant correlation in the age-associated changes markers of oxidative–nitrosative stress with changes in apoptotic signaling. The findings from this descriptive study imply that age-associated increases in mitochondrial-mediated apoptosis may be associated with the increase in oxidative-nitrosative stress in the aging F344xBN female heart.

Age-related changes in an antioxidant defense system in elderly patients with essential hypertension compared with healthy controls

BACKGROUND AND AIMS

Oxidative stress has been reported to increase with aging. Oxidative stress is also associated with hypertension, and antioxidant treatment has been shown to enhance antioxidant defense system. We therefore aimed to analyze the relationship between aging and some markers of oxidative stress in elderly patients with essential hypertension compared with healthy controls.

MATERIAL AND METHODS

Blood was collected from 18 patients with essential hypertension and 21 age- and sex-matched healthy controls aged over 65. Patients were on their usual medications while participating in the study. Oxidative stress parameters were investigated by measuring the concentration of glutathione (GSH) in whole blood and activities of glutathione peroxidase (GPx-1), glutathione reductase (GR), catalase (CAT), and Cu-Zn superoxide dismutase (CuZn SOD, SOD-1) in erythrocytes. GSH, GPx-1, GR, CAT, and CuZn SOD correlations with age were expressed as Pearson product-moment correlation coefficient r. Independent-samples T test was used to compare mean values of parameters between groups.

RESULTS

(1) Among all parameters analyzed herein, the activity of SOD-1 showed the most explicit decrease in relation to age, both in healthy controls and hypertensive subjects with r values of -0.54 (P = 0.05) and -0.68 (P < 0.01), respectively. (2) Age-related changes in parameters of oxidative stress did not differ significantly between groups. (3) Mean activity of SOD-1 was significantly higher (P < 0.05) in elderly hypertensives (2341.7 ± 213.71 U/g Hb) when compared with healthy controls (2199.7 ± 213.66 U/g Hb). (4) Mean GSH level was significantly higher (P < 0.01) in patients (3.1 ± 0.29 mmol/l) than in controls (2.8 ± 0.37 mmol/l). (5) Increased level of GSH in hypertension was followed by significantly (P < 0.01) higher activity of GR in this group when compared with controls (83.4 ± 15.25 and 64.1 ± 9.40 U/g Hb, respectively).

CONCLUSIONS

(1) The antioxidant barrier changes in elderly subjects with senescence. (2) CuZn SOD activity is negatively correlated with age and this association is not altered by factors that modulate the enzyme activity, such as hypertension and antihypertensive treatment. (3) Significantly higher concentration of GSH and significantly higher GR activity in patients may suggest a significant role of GSH metabolism in the pathogenesis of hypertension, as well as its contribution to the effect of antihypertensive treatment.

Profound cardioprotection with timolol in a female rat model of aging-related altered left ventricular function

Increasing evidence shows a marked beneficial effect with β-blockers in heart dysfunction via scavenging reactive oxygen species. Previously we showed that chronic treatment with either timolol or propranolol possessed similar beneficial effects for heart function in male rats as age increased, whereas only timolol exerted similar benefits in female rats. Therefore, in this study, we aimed first to examine the cellular bases for age-related alterations in excitation–contraction coupling in ventricular myocytes from female rats and, second, to investigate the hypothesis that age-related changes in [Ca2+]ihomeostasis and receptor-mediated system can be prevented with chronic timolol treatment. Chronic timolol treatment of 3-month-old female rats abolished age-related decrease in left ventricular developed pressure and the attenuated responses to β-adrenoreceptor stimulation. It also normalized the altered parameters of [Ca2+]itransients, decreased Ca2+loading of sarcoplasmic reticulum and increased basal [Ca2+]i, and decreased L-type Ca2+currents in 12-month-old female rats compared with the 3-month-old group. Adenylyl cyclase activity, β-adrenoreceptor affinity to its agonist, and β-adrenoreceptor density of the 12-month-old group are normalized to those of the 3-month-old group. Moreover, timolol treatment prevented dysfunction of the antioxidant system, including increased lipid peroxidation, decreased ratio of reduced glutathione to oxidized glutathione, and decreased activities of thioredoxin reductase and glucose-6-phosphate dehydrogenase, in the left ventricle of hearts from the 12-month-old group. Our data confirmed that aging-related early myocardial impairment is primarily related to a dysfunctional antioxidant system and impairment of Ca2+homeostasis, which can be prevented with chronic timolol treatment.

Deferasirox decreases age-associated iron accumulation in the aging F344XBN rat heart and liver

It is thought that aging in rats and humans is associated with increases in iron accumulation and cell apoptosis. Here, we examine the relationship between cardiac iron levels and apoptosis in aged F344XBN rats that had been treated with an oral iron chelator (Deferasirox; 100 mg/kg body weight) on alternate days for 6 months. Compared to adult animals (6 month), cardiac iron (+72%), liver iron (+87%), ferritin light chain (+59%), divalent metal transporter-1 (+56%) and the number of TdT-mediated dUTP nick end labeling (TUNEL) positive cells (4.3 fold increase) were higher in 33-month-old animals (P < 0.05). Deferasirox treatment decreased cardiac iron levels by 37% (P < 0.05), and this was associated with decreases in the number of TUNEL-positive cells. Age-associated increases in cell death were coupled with increases in Bax to Bcl-2 ratio, and the amount of Bad, full-length caspase-3, and cleaved caspase-3. Deferasirox treatment decreased the Bax to Bcl-2 ratio by 17% (P < 0.05) and the amount of Bad, full-length caspase-3, cleaved caspase-3 (19 kDa), and cleaved caspase-3 (17 kDa) by 41, 16, 22, and 37%, respectively (P < 0.05). Taken together, these data suggest that deferasirox may be effective in diminishing age-associated iron accumulation and cardiac apoptosis in the F344XBN rat model.

Oxidative stress alters renal D1 and AT1 receptor functions and increases blood pressure in old rats

Aging is associated with an increase in oxidative stress and blood pressure (BP). Renal dopamine D1 (D1R) and angiotensin II AT1 (AT1R) receptors maintain sodium homeostasis and BP. We hypothesized that age-associated increase in oxidative stress causes altered D1R and AT1R functions and high BP in aging. To test this, adult (3 mo) and old (21 mo) Fischer 344 × Brown Norway F1 rats were supplemented without/with antioxidant tempol followed by determining oxidative stress markers (urinary antioxidant capacity, proximal tubular NADPH-gp91phox, and plasma 8-isoprostane), D1R and AT1R functions, and BP. The D1R and AT1R functions were determined by measuring diuretic and natriuretic responses to D1R agonist (SKF-38393; 1 μg·kg(-1)·min(-1) iv) and AT1R antagonist (candesartan; 10 μg/kg iv), respectively. We found that the total urinary antioxidant capacity was lower in old rats, which increased with tempol treatment. In addition, tempol decreased the elevated NADPH-gp91phox and 8-isoprostane levels in old rats. Systolic, diastolic, and mean arterial BPs were higher in old rats and were reduced by tempol. Although SKF-38393 produced diuresis in both adult and old rats, urinary sodium excretion (UNaV) increased only in adult rats. While candesartan increased diuresis and UNaV in adult and old rats, the magnitude of response was greater in old rats. Tempol treatment in old rats reduced candesartan-induced increase in diuresis and UNaV. Our results demonstrate that diminished renal D1R and exaggerated AT1R functions are associated with high BP in old rats. Furthermore, oxidative stress may cause altered renal D1R and AT1R functions and high BP in old rats.

Vitamin E and C supplementation reduces oxidative stress, improves antioxidant enzymes and positive muscle work in chronically loaded muscles of aged rats

Aging is associated with increased oxidative stress. Muscle levels of oxidative stress are further elevated with exercise. The purpose of this study was to determine if dietary antioxidant supplementation would improve muscle function and cellular markers of oxidative stress in response to chronic repetitive loading in aging. The dorsiflexors of the left limb of aged and young adult Fischer 344 Brown×Norway rats were loaded 3 times weekly for 4.5 weeks using 80 maximal stretch-shortening contractions per session. The contra-lateral limb served as the intra-animal control. The rats were randomly assigned to a diet supplemented with Vitamin E and Vitamin C or normal non-supplemented rat chow. Biomarkers of oxidative stress were measured in the tibialis anterior muscle. Repetitive loading exercise increased maximal isometric force, negative work and positive work in the dorsiflexors of young adult rats. Only positive work increased in the aged animals that were supplemented with Vitamin E and C. Markers of oxidative stress (H(2)O(2), total GSH, GSH/GSSG ratio, malondialdehyde and 8-OHdG) increased in the tibialis anterior muscles from aged and young adult animals with repetitive loading, but Vitamin E and C supplements attenuated this increase. MnSOD activity increased with supplementation in the young adult animals. CuZnSOD and catalase activity increased with supplementation in young adult and aged animals and GPx activity increased with exercise in the non-supplemented young adult and aged animals. The increased levels of endogenous antioxidant enzymes after Vitamin E and C supplementation appear to be regulated by post-transcriptional modifications that are affected differently by age, exercise, and supplementation. These data suggest that antioxidant supplementation improves indices of oxidative stress associated with repetitive loading exercise and aging and improves the positive work output of muscles in aged rodents.

Possible molecular mechanisms underlying age-related cardiomyocyte apoptosis in the F344XBN rat heart

Despite advances in treatment, age-related cardiac dysfunction still remains a leading cause of cardiovascular death. Recent data have suggested that increases in cardiomyocyte apoptosis may be involved in the pathological remodeling of heart. Here, we examine the effects of aging on cardiomyocyte apoptosis in 6-, 30-, and 36-month-old Fischer344 x Brown Norway F1 hybrid rats (F344XBN). Compared with 6-month hearts, aged hearts exhibited increased TdT-mediated dUTP nick end labeling-positive nuclei, caspase-3 activation, caspase-dependent cleavage of alpha-fodrin and diminished phosphorylation of protein kinase B/Akt (Thr 308). These age-dependent increases in cardiomyocyte apoptosis were associated with alterations in the composition of the cardiac dystrophin glycoprotein complex and elevated cytoplasmic IgG and albumin immunoreactivity. Immunohistochemical analysis confirmed these data and demonstrated qualitative differences in localization of dystrophin-glycoprotein complex (DGC) molecules with aging. Taken together, these data suggest that aging-related increases in cardiac apoptotic activity model may be due, at least in part, to age-associated changes in DGC structure.

Alternate-day fasting protects the rat heart against age-induced inflammation and fibrosis by inhibiting oxidative damage and NF-kB activation

The free radical theory of aging is currently one of the most popular. In parallel, many studies have demonstrated the association of fibrosis and increased oxidative stress in the pathogenesis of some chronic human diseases, and fibrosis is often characteristic of aging tissues. One of the few interventions that effectively slow aging is calorie restriction and the protection against the age-associated increase of oxidative stress remains one of the foremost hypotheses to explain this action. As an alternative to traditional calorie restriction, another dietary regimen, termed alternate-day fasting, has also been tested, whose antiaging mechanisms have not been explored so much extensively. We thus studied the effects of alternate-day fasting, started at 2 months of age, on oxidative stress and fibrosis in the heart during aging. In the left ventricle of the heart of elderly (aged 24 months) versus young (aged 6 months) male rats we found a significant increase in oxidative stress paralleled by increased fibrosis. In parallel there was a significant increase in inflammatory cytokine levels and in NF-kB DNA binding activity with advancing age. Alternate-day fasting protected against all these age-related phenomena. These data support the hypothesis that this kind of dietary restriction protects against age-related fibrosis, at least in part by reducing inflammation and oxidative damage, and this protection can thus be considered a factor in the prevention of age-related diseases with sclerotic evolution.

Aging-dependent regulation of antioxidant enzymes and redox status in chronically loaded rat dorsiflexor muscles

This study compares changes in the pro-oxidant production and buffering capacity in young and aged skeletal muscle after exposure to chronic repetitive loading (RL). The dorsiflexors from one limb of young and aged rats were loaded 3 times/week for 4.5 weeks using 80 maximal stretch-shortening contractions per session. RL increased H2O2 in tibialis anterior muscles of young and aged rats and decreased the ratio of reduced/oxidized glutathione and lipid peroxidation in aged but not young adult animals. Glutathione peroxidase (GPx) activity decreased whereas catalase activity increased with RL in muscles from young and aged rats. RL increased CuZn superoxide disumutase (SOD) and Mn SOD protein concentration and CuZn SOD activity in muscles from young but not aged animals. There were no changes in protein content for GPx-1 and catalase or messenger RNA for any of the enzymes studied. These data show that aging reduces the adaptive capacity of muscles to buffer increased pro-oxidants imposed by chronic RL.