Age-related decrease of dehydroepiandrosterone concentrations in low density lipoproteins and its role in the susceptibility of low density lipoproteins to lipid peroxidation

Association between sex hormones and erectile dysfunction in men without hypoandrogenism

In addition to testosterone, various endocrine hormones, such as dehydroepiandrosterone sulfate (DHEA-S) and estradiol, may be involved in erectile function. However, the role of these sex hormones in the erectile function of men without hypoandrogenism remains unclear. This cross-sectional study included 398 community-dwelling men without hypoandrogenism. The participants were categorized into the non-ED and ED groups. Multivariable logistic regression analyses were performed to investigate the relationship between ED and serum sex hormone levels, including total testosterone, DHEA-S, estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin. Among the 398 men, 66 (17%) and 332 (83%) were categorized into the non-ED and ED groups, respectively. In the multivariable analyses, serum DHEA-S and estradiol levels were significantly associated with ED (odds ratio [OR]: 0.996, P = 0.030; OR: 1.082, P = 0.002; respectively), whereas serum total testosterone, LH, FSH, and prolactin levels did not demonstrate significant association. After adjusting for age, none of neutrophil-to-lymphocyte ratio, serum plasminogen activator inhibitor-1 levels, and skin advanced glycation end-products levels demonstrated significant correlation with serum DHEA-S and estradiol levels. In conclusion, lower testosterone levels did not affect ED in men with normal testosterone levels, whereas serum DHEA-S and estradiol levels were significantly associated with ED.

Extra Virgin Olive Oil Polyphenols Promote Cholesterol Efflux and Improve HDL Functionality

Results of the present work give evidence from the beneficial role of extra virgin olive of oil (EVOO) consumption towards oxidative stress and cardiovascular diseases. Polyphenols contained in EVOO are responsible for inhibiting lipoproteins oxidative damages and promoting reverse cholesterol transport process via ABCA1 pathway.

Higher serum dehydroepiandrosterone sulfate levels are protectively associated with depressive symptoms in men, but not in women: a community-based cohort study of older Japanese

OBJECTIVE

Dehydroepiandrosterone sulfate (DHEAS) appears to have a protective effect against depression, but evidence from prospective cohort studies is sparse. Therefore, we examined the association between serum DHEAS levels and depressive symptoms in older community-dwelling Japanese.

DESIGN

A community-based cohort study.

SETTING

Kurabuchi Town, Gunma Prefecture, Japan.

PARTICIPANTS

A total of 554 residents (248 men and 306 women) age 65 years or older without depressive symptoms at baseline.

MEASUREMENTS

We performed a baseline examination of the subjects between 2005 and 2006 to determine serum DHEAS levels. The subjects were categorized into three groups based on age strata- and sex-specific tertiles of DHEAS. Depressive symptoms were assessed with the Geriatric Depression Scale 15-item version (GDS-15) in face-to-face home visit interviews carried out once in 2007 and once in 2008. The association of DHEAS with depressive symptoms (GDS-15 ≥ 6) was analyzed with the use of logistic regression models.

RESULTS

The incidence of depressive symptoms was 12.1% in men and 19.6% in women. In men, the multiadjusted odds ratio of depressive symptoms was 0.24 (95% confidence interval: 0.06-0.94, Wald χ2 = 4.20, degrees of freedom = 1, p = 0.04) for the highest tertile compared with the lowest. The association observed for the highest versus the lowest remained significant even after adjustment for physical performance and cognitive function. In women, DHEAS was not associated with depressive symptoms.

CONCLUSIONS

In this study, higher serum DHEAS levels were found to be protectively and independently associated with the risk of developing depressive symptoms in men, but not in women.

The anti-inflammatory effect of paraoxonase 1 against oxidized lipids depends on its association with high density lipoproteins

AIM

The aims of this study were to investigate whether purified PON1 can reduce the pro-inflammatory effect of oxidized phospholipids and whether the effect depended on its association with HDL.

MAIN METHODS

Lipid peroxidation was induced by copper ions and was measured using the conjugated diene method. Lysophosphatidylcholine (lyso-PC) formation was measured by HPLC with evaporative light scattering detection (ELSD) and ICAM-1 expression on Ea.hy926 endothelial cells was analyzed by flow cytometry.

KEY FINDINGS

Purified PON1 significantly inhibited copper-induced oxidation of LDL and HDL, causing a 60.5% and 77.7% decrease in conjugated diene formation, respectively. Incubating PON1 with oxLDL caused a significant increase in lyso-PC levels, while oxHDL caused a significant decrease. PON1 (12.5 to 50 μg/mL) had a pro-inflammatory effect in the presence of oxLDL, increasing ICAM-1 levels in Ea.hy926 cells by 33.0% and 40.6% (p<0.001) respectively, and had an anti-inflammatory effect in the presence of oxHDL, causing a 3-fold reduction in ICAM-1 levels. PON1 also caused a significant decrease in TNFα and purified lyso-PC-induced ICAM-1 expression. The results obtained with reconstituted HDL as well as LCAT and PAF-AH inhibitors suggested that the anti-inflammatory effect of PON1 against oxidized lipids is dependent on its association with HDL.

SIGNIFICANCE

Our results clearly showed that PON1 is involved in the anti-inflammatory effect of HDL and that the effect appears to depend on its association with HDL.

Effects on lipoprotein particles of long-term dehydroepiandrosterone in elderly men and women and testosterone in elderly men

CONTEXT

Although age-related declines in dehydroepiandrosterone sulfate (DHEAS) and testosterone are associated with cardiovascular risk, it remains to be determined whether replacement of these hormones improves cardiovascular risk factors.

OBJECTIVE

This study sought to determine the effect of long-term replacement of dehydroepiandrosterone (DHEA) in elderly men and women and testosterone in elderly men on lipid and lipoprotein concentrations and particle sizes.

METHODS

A 2-yr randomized, placebo-controlled, double-blind study was conducted in 87 elderly men with low levels of DHEAS and bioavailable testosterone and 57 elderly women with low levels of DHEAS. Among elderly men, 29 received DHEA (75 mg/d), 27 received testosterone (5 mg/d), and 31 received placebo. Among the elderly women, 27 received DHEA (50 mg/d), and 30 received placebo. Baseline lipoprotein profiles in the elderly were compared to healthy younger participants. Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particle sizes and concentrations were quantified using nuclear magnetic resonance spectroscopy.

RESULTS

The elderly had higher concentrations of total cholesterol, triglycerides, LDL cholesterol, total LDL particles, and small, dense LDL particles than the young. In men, neither DHEA nor testosterone affected LDL or HDL particle concentrations. In women, DHEA reduced HDL cholesterol [median difference (95% confidence intervals), -5.0 (-8.0, -2.0) mg/dl; P = 0.002] and the number of large HDL particles [-1.0 (-1.8, -0.2) micromol/liter; P = 0.003].

CONCLUSIONS

Long-term DHEA and testosterone had no significant effect on plasma lipoproteins in elderly men, but elderly women showed a lowering of the large HDL particles that may have potential adverse clinical implications.

Protective effects of Peganum harmala L. extract, harmine and harmaline against human low-density lipoprotein oxidation

Oxidative modification of low-density lipoprotein (LDL) particles has been implicated in the process of atherogenesis. Antioxidants that prevent LDL from oxidation may reduce atherosclerosis. We have investigated the protective effect of Peganum harmala-extract (P-extract) and the two major alkaloids (harmine and harmaline) from the seeds of P. harmala against CuSO4-induced LDL oxidation. Through determination of the formation of malondialdehyde (MDA) and conjugated diene as well as the lag phase, the extract (P-extract) and compounds were found to possess an inhibitory effect. Moreover, harmaline and harmine reduced the rate of vitamin E disappearance and exhibited a significant free radical scavenging capacity (DPPH•). However, harmaline had a markedly higher antioxidant capacity than harmine in scavenging or preventive capacity against free radicals as well as inhibiting the aggregation of the LDL protein moiety (apolipoprotein B) induced by oxidation. The results suggested that P. harmala compounds could be a major source of compounds that inhibit LDL oxidative modification induced by copper.

Effect of apolipoprotein a-I complex with tetrahydrocortisone on protein biosynthesis and glucose absorption by rat hepatocytes

We studied the effect of apolipoprotein A-I-tetrahydrocortisone complex on (14)C glucose absorption and lactate accumulation and on the rate of protein biosynthesis in isolated rat hepatocytes. The presence of apolipoprotein A-I-tetrahydrocortisone complex in the incubation medium increased absorption of labeled glucose by hepatocytes by 52%, while lactate content in the conditioning medium increased 4-fold. The rate of protein biosynthesis increased by 80% in comparison with control cells. It is hypothesized that the increase in protein biosynthesis rate in hepatocytes under the effect of apolipoprotein A-I-tetrahydrocortisone complex is due to stimulation of energy metabolism, specifically, of its glycolytic component.

Frailty in the elderly is associated with insulin resistance of glucose metabolism in the postabsorptive state only in the presence of increased abdominal fat

Whether frail elderly subjects are more insulin resistant (IR) than non-frail is unclear. How obesity, muscle mass, inflammation, hormonal and lipid status, oxidative stress, antioxidant capacity and physical activity influences insulin sensitivity (IS) in frail elderly subjects remains uncertain. We determined (1) whether frail elderly persons are more IR than non-frail elderly and (2) the influence of abdominal fat mass (AFM), muscle mass index (MMI), inflammation (CRP), hormonal (cortisol, free IGF-1, DHEA) and lipid (FFA, triglyceride (TG)) status, oxidative stress (paraoxonase-1 (PON-1), malondialdehyde (MDA)), antioxidant capacity (vitamin C, E) and physical activity (PASE questionnaire) on IS (QUICKI) in 16 frail obese (FO), 17 frail lean (FL) and 21 healthy, non-obese (HN) elderly subjects. IS was lower in FO than FL, but there was no significant difference between HN and FO or FL. There were no significant differences among groups for CRP, cortisol, IGF-1, DHEA, FFA, TG, PON-1, MDA, vitamin C and E and PASE. Age, AFM and MMI significantly correlated with IS. Only AFM and MMI were significant predictors explaining, respectively, 18.5% and 8.5% of the variance in IS. Increased abdominal obesity is associated with IR in frail elderly. Non-obese frail persons are not more IR than their healthy counterparts.

Age-associated decrease of high-density lipoprotein-mediated reverse cholesterol transport activity

High-density lipoproteins (HDL) are considered atheroprotective in contrast to low-density lipoproteins (LDL), which are atherogenic in their oxidized form. A growing body of evidence suggests that HDL exert part of their antiatherogenic effect by counteracting LDL oxidation as well as their proinflammatory effect. However, a number of studies, carried over the past 30 years, have shown that cholesterol efflux plays a major role in the atheroprotective effects of HDL and cholesterol homeostasis. These studies have further identified the scavenger receptor type B-I (SR-BI), the adenosine triphosphate (ATP)-binding cassette transporters ATP-binding cassette subfamily A1 (ABCA1), ATP-binding cassette subfamily G1 (ABCG1) and ABCG4, the liver X receptor/retinoid X receptor (LXR/RXR) and peroxisome proliferator-activated receptorgamma(PPAR gamma) transcription factors, the HDL components apolipoprotein A-I (apoA-I), lecithin-cholesterol acyltransferase (LCAT), and phospholipids as additional mediators of cholesterol transport. Cholesterol efflux occurs via three independent pathways: (1) aqueous diffusion, (2) nonspecific efflux via SR-BI receptors, and (3) specific efflux via cholesterol-responsive members of the ABC superfamily. Whereas aqueous diffusion and scavenger receptor class B, type I (SR-BI)-mediated efflux transport free cholesterol to a wide variety of cholesterol acceptors (particles containing phospholipids, HDL, and lipidated apo-lipoproteins; LDL, etc), the ABCA1 pathway mediates the transport of cholesterol in a unidirectional manner, mainly to lipid-poor apoA-I. In contrast, the ABCG1 pathway is responsible for the transport of cholesterol to all the subfamily members of HDL. Although HDL-mediated cholesterol efflux is apoA-I-dependent, recent studies have suggested an involvement of the enzyme paraoxonase 1 (PON1). Cholesterol efflux is carried on by a number of factors such as genetic mutations, smoking, stress, and high-fat diets. It is attenuated with aging due to changes in the composition and structure of HDL, especially the phosphatidylcholine/sphingomyelin ratio, the fluidity of the phospholipidic layer, the concentration of apoA-I, and the activity of PON1. This review summarizes the findings that cholesterol homeostasis is disrupted with aging as a consequence of dysfunctional cholesterol efflux and the impairment of physiological functions.

A new insight into resveratrol as an atheroprotective compound: inhibition of lipid peroxidation and enhancement of cholesterol efflux

Resveratrol, a polyphenolic constituent of red wine, is known for its anti-atherogenic properties and is thought to be beneficial in reducing the incidence of cardiovascular diseases (CVD). However, the mechanism of action by which it exerts its anti-atherogenic effect remains unclear. In this study, we investigated the relationship between the antioxidant effects of resveratrol and its ability to promote cholesterol efflux. We measured the formation of conjugated dienes and the rate of lipid peroxidation, and observed that resveratrol inhibited copper- and irradiation-induced LDL and HDL oxidation as observed by a reduction in oxidation rate and an increase in the lag phase (p<0.05). We used DPPH screening to measure free radical scavenging activity and observed that resveratrol (0-50microM) significantly reduced the content of free radicals (p<0.001). Respect to its effect on cholesterol homeostasis, resveratrol also enhanced apoA-1-mediated cholesterol efflux (r(2)=0.907, p<0.05, linear regression) by up-regulating ABCA-1 receptors, and reduced cholesterol influx or uptake in J774 macrophages (r(2)=0.89, p<0.05, linear regression). Incubation of macrophages (J774, THP-1 and MPM) with Fe/ascorbate ion, attenuated apoA-1 and HDL(3)-mediated cholesterol efflux whereas resveratrol (0-25microM) significantly redressed this attenuation in a dose-dependent manner (p<0.001). Resveratrol thus appears to be a natural antioxidant that enhances cholesterol efflux. These properties make it a potential natural antioxidant that could be used to prevent and treat CVD.

Effects of D-003, a mixture of high-molecular-weight sugar cane wax acids, on lipid peroxidation markers in older individuals: A randomized, double-blind, placebo-controlled study

BACKGROUND

Aging is associated with increased lipid peroxidation (LP). D-003, a mixture of long-chain aliphatic primary acids purified from sugar cane wax, has been found to inhibit LP in experimental models and in healthy subjects.

OBJECTIVES

The aim of this study was to assess the effects of D-003 on LP markers and the lipid profile of older individuals.

METHODS

This randomized, double-blind, placebo-controlled study was conducted at the Plaza Veterans' House, Havana City, Cuba. Male and female patients aged ≥60 years with total cholesterol values of <6.1 mmol/L were eligible for inclusion in the study. After a 3-week lead-in and baseline assessment period, patients were randomized to receive PO D-003 5 mg/d, D-003 10 mg/d, or placebo for 8 weeks. The effect on copper-induced LP of low-density lipoprotein (LDL) particles was the primary variable, and the effects on plasma total antioxidant status (TAS), plasma malondialdehyde (MDA) concentration, plasma antioxidant enzyme (superoxide dismutase and glutathione peroxidase) activities, and the lipid profile were secondary variables. A clinical examination was performed at each visit (baseline, weeks 4 and 8). A clinical examination, LP, and blood tests (lipid profile, hematologic, and blood biochemistry safety indicators) were performed at baseline and after 8 weeks of treatment. Compliance and adverse events (AEs) were assessed at weeks 4 and 8. A 2-tailed P < 0.05 was considered statistically significant for comparisons of both continuous and categoric variables.

RESULTS

Fifty-four patients aged ≥60 years were assessed for inclusion in the study, and 51 patients (40 women, 11 men; mean [SD] age, 67 [6] years) were included in the study. The lag phase of conjugated diene formation increased significantly and in a dose-dependent manner in the group treated with D-003 5 mg (24.7%; P < 0.01) and in the group treated with D-003 10 mg (29.3%; P < 0.01) compared with placebo. The maximal rate of conjugated diene propagation decreased significantly in the D-003 5- and 10-mg groups -22.7% and -25.8%, respectively; both, P < 0.05) compared with placebo. TAS increased significantly (17.7% and 23.0%, respectively; both, P < 0.01) in both active treatment groups compared with placebo. Plasma MDA concentration decreased significantly in the D-003 10-mg group (-28.6%; P < 0.05) but not in the D-003 5-mg group, compared with placebo. These changes were also significant compared with baseline. Antioxidant enzyme activities did not change in the active treatment groups compared with placebo or baseline. In the D-003 5- and 10-mg groups, significant decreases were found in LDL cholesterol concentration (-15.8% and -23.8%, respectively; both, P < 0.001) and total cholesterol concentration (-13.0% and -16.8%, both, P < 0.05) compared with placebo. High-density lipoprotein cholesterol concentration increased significantly in the D-003 5-mg group (5.7%; P < 0.05) and the D-003 10-mg group (18.2%; P < 0.001) compared with placebo. Changes in the lipid profile were also significant compared with baseline. In the placebo group, no variable changed significantly compared with baseline. D-003 was well tolerated at both dose levels, and no patient withdrew from the study. There were a total of 3 AEs reported: insomnia and acidity in 2 patients receiving placebo; and heartburn in 1 patient receiving D-003 5 mg.

CONCLUSIONS

D-003 5 and 10 mg/d administered to these older individuals (aged ≥60 years) for 8 weeks inhibited LP of LDL and increased TAS in a dose-dependent manner, while plasma MDA concentration decreased in the patients receiving D-003 10 mg/d only. D-003 was well tolerated at both doses.

Evidence of accelerated ageing in clinical drug addiction from immune, hepatic and metabolic biomarkers

BACKGROUND

Drug addiction is associated with significant disease and death, but its impact on the ageing process has not been considered. The recent demonstration that many of the items available in routine clinical pathology have applicability as biomarkers of the ageing process implies that routine clinical laboratory parameters would be useful as an initial investigation of this possibility.

METHODS

12,093 clinical laboratory results 1995-2006 were reviewed. To make the age ranges of the medical and addicted groups comparable the age range was restricted to 15-45 years.

RESULTS

739 drug addicted (DA) and 5834 general medical (GM) age matched blood samples were compared. Significant elevation of immune parameters was noted in the C-reactive protein, erythrocyte sedimentation rate, total lymphocyte count, serum globulins and the globulin:albumin ratio (P < 0.01). Alanine aminotranferase, creatinine, urea, and insulin like growth factor-1 were also significantly higher (P < 0.01) in the DA group. Albumin, body mass index and dihydroepiandrosterone sulphate were unchanged and cholesterol was lower (all P < 0.05).

CONCLUSION

These data demonstrate for the first time that addiction is associated with an altered profile of common biomarkers of ageing raising the possibility that the ageing process may be altered in this group. Infective and immune processes may be centrally involved. They suggest that addiction forms an interesting model to further examine the contribution of immune suppression and hyperstimulation to the ageing process.

Antiatherogenic activity of extracts of Argania spinosa L. pericarp: beneficial effects on lipid peroxidation and cholesterol homeostasisThis article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products

Prevention of lipoprotein oxidation by natural compounds may prevent atherosclerosis via reducing early atherogenesis. In this study, we investigated for the first time the beneficial properties of methanolic extract of argania pericarp (MEAP) towards atherogenesis by protecting human low-density lipoprotein (LDL) against oxidation while promoting high-density lipoprotein (HDL)-mediated cholesterol efflux. By measuring the formation of malondialdehyde (MDA) and conjugated diene as well as the lag phase and the progression rate of lipid peroxidation, the MEAP was found to possess an inhibitory effect. In addition, MEAP reduced the rate of disappearance of α-tocopherol as well as the apoB electrophoretic mobility in a dose-dependent manner. These effects are related to the free radical scavenging and copper-chelating effects of MEAP. In terms of cell viability, MEAP has shown a cytotoxic effect (0–40 μg/mL). Incubation of3H-cholesterol-loaded J774 macrophages with HDL in the presence of increasing concentrations of MEAP enhanced HDL-mediated cholesterol efflux independently of ABCA1 receptor pathways. Our findings suggest that argania seed pericarp provides a source of natural antioxidants that inhibit LDL oxidation and enhance cholesterol efflux and thus can prevent development of cardiovascular diseases.

Marrubium vulgare extract inhibits human-LDL oxidation and enhances HDL-mediated cholesterol efflux in THP-1 macrophage

The objective of the present study was to elucidate the beneficial properties of aqueous extracts of Marrubium vulgare (AEM) towards cardiovascular disease by protecting human-LDL against lipid peroxidation and promoting HDL-mediated cholesterol efflux. Human-LDL were oxidised by incubation with CuSO(4) in the presence of increased concentrations of AEM (0-100 microg/ml). LDL lipid peroxidation was evaluated by conjugated diene formation, vitamin E disappearance as well as LDL-electrophoretic mobility. HDL-mediated cholesterol efflux assay was carried out in human THP-1 macrophages. Incubation of LDL with AEM significantly prolonged the lag phase (P=0.014), lowered the progression rate of lipid peroxidation (P=0.004), reduced the disappearance of vitamin E and the electrophoretic mobility in a dose-dependent manner. Also, incubation of HDL with AEM significantly increased HDL-mediated cholesterol efflux from THP-1 macrophages implicating an independent ATP binding cassette A1 (ABCA1) pathways. Our findings suggest that M. vulgare provides a source of natural antioxidants, which inhibit LDL oxidation and enhance reverse cholesterol transport and thus can prevent cardiovascular diseases development. These antioxidant properties increase the anti-atherogenic potential of HDL.

Phenolic-extract from argan oil (Argania spinosa L.) inhibits human low-density lipoprotein (LDL) oxidation and enhances cholesterol efflux from human THP-1 macrophages

Argan oil is rich in unsaturated fatty acids, tocopherol and phenolic compounds. These protective molecules make further study of its cardiovascular diseases (CVDs) action interesting. Furthermore, no previous study has explored the antioxidant activity of argan oil in comparison with olive oil. The present study was conducted to evaluate the beneficial properties of Virgin argan oil phenolic extracts (VAO-PE) towards CVD by: (A) protecting human (low-density lipoprotein, LDL) against lipid peroxidation and (B) promoting high-density lipoprotein (HDL)-mediated cholesterol efflux. Human LDLs were oxidized by incubation with CuSO(4) in the presence of different concentrations of VAO-PE (0-320mug/ml). LDL lipid peroxidation was evaluated by conjugated diene and MDA formation as well as Vitamin E disappearance. Incubation of LDL with VAO-PE significantly prolonged the lag-phase and lowered the progression rate of lipid peroxidation (P<0.01) and reduced the disappearance of Vitamin E in a concentration-dependent manner. Incubation of HDL with VAO-PE significantly increased the fluidity of the HDL phospholipidic bilayer (P=0.0004) and HDL-mediated cholesterol efflux from THP-1 macrophages. These results suggest that Virgin argan oil provides a source of dietary phenolic antioxidants, which prevent cardiovascular diseases by inhibiting LDL-oxidation and enhancing reverse cholesterol transport. These properties increase the anti-atherogenic potential of HDL.

Up-regulation of advanced glycated products receptors in the brain of diabetic rats is prevented by antioxidant treatment

Diabetics have at least twice the risk of stroke and may show performance deficit in a wide range of cognitive domains. The mechanisms underlying this gradually developing end-organ damage may involve both vascular changes and direct damage to neuronal cells as a result of overproduction of superoxide by the respiratory chain and consequent oxidative stress. The study aimed to assess the role of oxidative stress on the aldose reductase-polyol pathway, on advanced glycated end-product (AGE)/AGE-receptor interaction, and on downstream signaling in the hippocampus of streptozotocin-treated rats. Data show that, in diabetic rats, levels of prooxidant compounds increase, whereas levels of antioxidant compounds fall. Receptor for AGE and galectin-3 content and polyol flux increase, whereas glyceraldehyde-3-phosphate dehydrogenase activity is impaired. Moreover, nuclear factor kappaB (p65) transcription factor levels and S-100 protein are increased in the hippocampus cytosol, suggesting that oxidative stress triggers the cascade of events that finally leads to neuronal damage. Dehydroepiandrosterone, the most abundant hormonal steroid in the blood, has been reported to possess antioxidant properties. When dehydroepiandrosterone was administered to diabetic rats, the improved oxidative imbalance and the marked reduction of AGE receptors paralleled the reduced activation of nuclear factor kappaB and the reduction of S-100 levels, reinforcing the suggestion that oxidative stress plays a role in diabetes-related neuronal damage.

Consumption of argan oil may have an antiatherogenic effect by improving paraoxonase activities and antioxidant status: Intervention study in healthy men

BACKGROUND AND AIM

Due to its high antioxidant and mono- and polyunsaturated fatty acid content virgin argan oil (VAO) could play a beneficial role in cardiovascular prevention. We were therefore interested in determining whether the consumption of VAO could improve plasma paraoxonase (PON1) activities and antioxidant status in healthy men.

METHODS AND RESULTS

Sixty young men were included in this interventional study. They were given a controlled diet for 2 weeks as baseline and then received 25 g/day of butter. The group was randomised to two diet group periods of 3 weeks each. The VAO group received 25 ml/day of oil and the extra virgin olive oil (EVO) group received the same quantity of EVO as control group. Plasma PON1 activities, antioxidant vitamins and LDL susceptibility to oxidation were measured. The analysis of the results shows that PON1 activities increase significantly in both groups and that lipoperoxides and conjugated dienes formation decreases significantly in VAO and EVO groups compared to baseline values (P=0.001 and P=0.014, respectively). Vitamin E concentration increases significantly only in VAO group (P=0.007). Susceptibility of LDL to lipid peroxidation shows a significant increase in lag phase and a significant decrease in maximum diene production in VAO (P=0.005) and EVO groups (P=0.041 and P=0.005, respectively).

CONCLUSIONS

Our findings confirm the beneficial effect of EVO on plasma antioxidant status and show for the first time the same effect for VAO supplementation in man. Thus, VAO offers an additional natural food supplement to reduce cardiovascular risk.

Age-related decrease in high-density lipoproteins antioxidant activity is due to an alteration in the PON1's free sulfhydryl groups

The aim of this study was to evaluate the antioxidant activity of HDL with aging and to investigate the implication of PON1 in this process. The study involved 54 healthy subjects distributed in two age groups, young (20-25 years) and elderly (65-85 years). Lipid peroxidation was induced by *OH and O2*- oxygen free radicals produced by gamma-radiolysis of water. LDL oxidation was followed by the measurement of conjugated diene (CD), lipid peroxide (LP) and malondialdehyde (MDA) formation. PON1 was purified separately from young (Y-PON1) and elderly subjects (E-PON1). PON1 activity and structure was followed by measurement of PON1 paraoxonase (p.ase) activity, titration of the SH groups, and electrophoretic mobility by SDS-PAGE. Our results show a significant decrease in the HDL antioxidant activity: percentage of protection against CD formation=27.70% (p<0.01) for E-HDL versus 73.08% (p<0.001) for Y-HDL. Moreover, E-PON1 showed a lower antioxidant activity when compared to Y-PON1 47.08% versus 78.14%, respectively (p<0.0001). Exposition of PON1 to *OH and O2*- oxygen free radicals induced a significant decrease in PON1 p.ase activity as well as a reduction in the number of PON1's free sulfhydryl groups. Moreover, our results show a close association between PON1's free sulfhydryl groups and its capacity to protect LDL against lipid peroxidation. There was a significant decrease in the number of free sulfhydryls between Y-PON1 and E-PON1 with respect to cysteine-284 amino acid residues (p<0.0092).

Is brain dehydroepiandrosterone synthesis modulated by free radicals in mice?

Dehydroepiandrosterone (DHEA) is a neurosteroid synthesized de novo in the brain, in addition to the periphery, modulating some membrane, ion-gated channel neurotransmitter receptors. P450-17alpha-hydroxylase activity converting pregnenolone to DHEA, has not yet been identified in the brain of rodents. Studies in brain-derived primary cultures and cell lines, suggest a possible alternative pathway for DHEA synthesis involving oxygenated hydroxyperoxides. We investigated DHEA synthesis in the brains of castrated male mice before and after treatment with N-acetylcysteine amide (AD4) (a newly developed brain penetrating antioxidant). We found a significant increase in brain DHEA level 24 h after castration, which was totally blocked by AD4. This blockade of castration-induced increased brain DHEA synthesis, supports the assumption that this synthesis may also be affected by free radicals. This is the first in vivo study indicating the possible existence of an in-brain oxidative stress-related pathway leading to brain DHEA production.

Studies on homocysteine and dehydroepiandrosterone sulphate plasma levels in Alzheimer's disease patients and in Parkinson's disease patients

Homocysteine (HC) and dehydroepiandrosterone sulphate (DHEAS) plasma levels have been evaluated in groups of male and female patients with Parkinson's disease (PD) and in a group of female patients with Alzheimer's disease (AD) and compared with the corresponding plasma levels observed in a group of age-matched subjects. It has been confirmed that HC plasma levels are enhanced in both PD and AD patients. As far as the DHEAS plasma levels are concerned no changes have been observed in PD patients while a marked decrease has been observed in AD patients. These results support the view that while the pro-oxidant effects of HC and its agonist action at NMDA receptors can play a role in both neurodegenerative diseases, the role of DHEAS is more complex and may be an important factor only in certain neurodegenerative diseases. Thus, according to the present study DHEAS is likely to be involved in AD but not in PD.

Oxidation of protein in human low-density lipoprotein exposed to peroxyl radicals facilitates uptake by monocytes; protection by antioxidants in vitro

Generation of neoepitopes on apolipoprotein B within oxidised low-density lipoprotein (LDL) is important in the unregulated uptake of LDL by monocytic scavenger receptors (CD36, SR-AI, LOX-1). Freshly isolated LDL was oxidised by peroxyl radicals generated from the thermal decomposition of an aqueous azo-compound. We describe that formation of carbonyl groups on the protein component is early as protein oxidation was seen after 90min. This is associated with an increased propensity for LDL uptake by U937 monocytes. Three classes of antioxidants (quercetin, dehydroepiandrosterone (DHEA) and ascorbic acid) have been examined for their capacity to inhibit AAPH-induced protein oxidation, (protein carbonyls, Δ electrophoretic mobility and LDL uptake by U937 monocytes). CD36 expression was assessed by flow cytometry and was seen to be unaltered by oxidised LDL uptake. All three classes were effective antioxidants, quercetin (P<0.01), ascorbic acid (P<0.01), DHEA (P<0.05). As LDL protein is the control point for LDL metabolism, the degree of oxidation and protection by antioxidants is likely to be of great importance for (patho)-physiological uptake of LDL by monocytes.

Oxidative stress and kidney dysfunction due to ischemia/reperfusion in rat: attenuation by dehydroepiandrosterone

BACKGROUND

The pathogenesis of ischemia/reperfusion (I/R) involves generation of reactive oxygen and nitrogen species. This in vivo study investigates the effect of dehydroepiandrosterone (DHEA), a physiologic steroid with antioxidant properties, on oxidative balance and renal dysfunctions induced by monolateral I/R.

METHODS

Normal and DHEA-treated rats (4 mg/day x 21 days, orally) were subjected to monolateral renal I/R (30 minutes/6 hours). The oxidative state was determined by measuring hydrogen peroxide level and activities of glutathione-peroxidase, catalase, and superoxide dismutase. Tumor necrosis factor-alpha (TNF-alpha) and nitric oxide production and inducible nitric oxide synthase (iNOS) levels were also measured. Hydroxynonenal content was used to probe lipid peroxidation. Functional parameters determined were creatinine levels and Na/K-ATPase activity. Immunohistochemical and morphologic studies were also performed.

RESULTS

A markedly pro-oxidant state was evident in the kidney of rats subjected to I/R. Both hydrogen peroxide and reactive nitrogen species (nitric oxide and iNOS) increased, whereas antioxidants decreased. Oxidant species induce TNF-alpha increase, which, in turn, produces lipoperoxidative processes, as documented by the increased hydroxynonenal (HNE) level. As final result, impaired renal functionality, hydropic degeneration, and vacuolization of proximal convolute tubules were observed in kidneys of I/R rats. DHEA pretreatment improved the parameters considered.

CONCLUSION

I/R induces oxidative stress and consequently damages the proximal convolute renal tubules. Rats supplemented with DHEA and subjected to I/R had reduced pro-oxidant state, oxidative damage, and improved renal functionality, indicating an attenuation of oxidative injury and dysfunctions mediated by I/R.

Pro-oxidant effect of dehydroepiandrosterone in rats is mediated by PPAR activation

DHEA-treatment exerts a dual effect, prooxidant or antioxidant, depending on the dosage and, therefore, on the tissue concentration reached. In agreement with previous studies showing a prooxidant effect of DHEA, here we show that pharmacological doses of DHEA produce increased H(2)O(2) levels and a marked reduction of GSH content in rat liver. DHEA, also increases both catalase (by 30%) and cytochrome-C-reductase (by 30%) activities in the liver cytosol. The effectiveness of the state of increased oxidative stress is also documented by changes in fatty acid pattern of the microsomal membranes. Moreover, DHEA, at high doses, enhances beta-oxidation, as demonstrated by an increase of acyl-CoA-oxidase activity and of cytochrome P450 4A content, confirming that it acts as a PPARs inducer. Both PPARs induction and proxidant effects completely disappear when DHEA is administered at lower doses. Seven days treatment (4 or 10 mg) is unable to affect either levels of proxidant species and of antioxidant molecules, or cytochrome P450 4A content and beta-oxidation. Prolonged DHEA treatment (4 mg/day) for three weeks not only is unable to affect PPARs activation and beta-oxidation, but it also exerts a protective effect against ADP/Fe(2+) induced lipid peroxidation. This latter result confirms the antioxidant effects of DHEA at low doses, as already previously documented.

[Molecular mechanisms of the protective effect of vitamin e against atherosclerosis]

Oxidation of low-density lipoproteins constitutes the first step of a very complex process leading to atherosclerosis. Vitamin E, and principally a-tocopherol, is considered as the principal inhibitor of lipid peroxidation. Some studies showed the beneficial role of vitamin E in the prevention and reduction of atherosclerosis and its associated pathologies. However, other in vitro studies advance a prooxidant role of vitamin E. The results of the epidemiologic studies are difficult to generalize without taking account of the clinical randomized tests. In this work, we reviewed the principal studies devoted to the role of vitamin E and discussed the assumption of a prooxidant effect of this molecule.

Study of the paraoxonase and platelet-activating factor acetylhydrolase activities with aging

The purpose of this study was to investigate, with aging, the activity of two enzymes associated to HDL and responsible for its anti-atherogenic activity; paraoxonase (PON1) and platelet-activating factor acetylhydrolase (PAF-AH). Ninety-five subjects aged between 26 and 77 years were recruited for the study. The prevalence of phenotype A, AB, and B in our subjects group was 69.47,21.05 and 9.47% respectively. Plasma as well as HDL paraoxonase activity decreased significantly with aging (r =-0.218, P < 0.039) and (r = -0.280, P < 0.006) respectively. PAF-AH activity was unchanged with aging however, we noted a negative correlation between PAF-AH and PON1 activity in HDL (r = -0.243, P < 0.02) and in LDL vs HDL (r =-0.462, P < 0.001).

Oxidative stress and eicosanoids in the kidneys of hyperglycemic rats treated with dehydroepiandrosterone

Oxidative stress plays a crucial role in the pathogenesis of chronic diabetic complications. Normoglycemic and streptozotocin-diabetic rats were treated with dehydroepiandrosterone (DHEA) (4 mg/d per rat) for 3 weeks. At the end of treatment, hydroxynonenal, hydroperoxyeicosatetraenoic acids and antioxidant levels, as well as Na/K-ATPase activity and membrane fatty acids composition were evaluated in kidney homogenates. Chronic hyperglycemia caused a marked increase of both hydroxynonenal and lipoxygenase pathway products and a drop in both GSH levels and membrane Na/K-ATPase activity. DHEA treatment restored the antioxidant levels to close to the control value and considerably reduced hydroxynonenal and hydroperoxyeicosatetraenoic acid levels. Moreover, DHEA counteracted the detrimental effect of hyperglycemia on membrane function: the drop of Na/K-ATPase activity in diabetic animals was significantly inhibited by DHEA treatment. These results show that DHEA reduces oxidative stress and the consequent increase of lipoxygenase pathway products induced by experimental diabetes in rat kidney; they also suggest that, by reducing the inflammatory response to oxidative stress, DHEA treatment might delay the progression of diabetic kidney disease.

Hyposecretion of the adrenal androgen dehydroepiandrosterone sulfate and its relation to clinical variables in inflammatory arthritis

Hypothalamic-pituitary-adrenal underactivity has been reported in rheumatoid arthritis (RA). This phenomenon has implications with regard to the pathogenesis and treatment of the disease. The present study was designed to evaluate the secretion of the adrenal androgen dehydroepiandrosterone sulfate (DHEAS) and its relation to clinical variables in RA, spondyloarthropathy (Spa), and undifferentiated inflammatory arthritis (UIA). Eighty-seven patients (38 with RA, 29 with Spa, and 20 with UIA) were studied, of whom 54 were women. Only 12 patients (14%) had taken glucocorticoids previously. Age-matched, healthy women (134) and men (149) served as controls. Fasting blood samples were taken for determination of the erythrocyte sedimentation rate (ESR), serum DHEAS and insulin, and plasma glucose. Insulin resistance was estimated by the homeostasis-model assessment (HOMAIR). DHEAS concentrations were significantly decreased in both women and men with inflammatory arthritis (IA) (P < 0.001). In 24 patients (28%), DHEAS levels were below the lower extreme ranges found for controls. Multiple intergroup comparisons revealed similarly decreased concentrations in each disease subset in both women and men. After the ESR, previous glucocorticoid usage, current treatment with nonsteroidal anti-inflammatory drugs, duration of disease and HOMAIR were controlled for, the differences in DHEAS levels between patients and controls were markedly attenuated in women (P = 0.050) and were no longer present in men (P = 0.133). We concluded that low DHEAS concentrations are commonly encountered in IA and, in women, this may not be fully explainable by disease-related parameters. The role of hypoadrenalism in the pathophysiology of IA deserves further elucidation. DHEA replacement may be indicated in many patients with IA, even in those not taking glucocorticoids.

Biogerontological research in Canada

There is an ever increasing interest in the study of the aging process. This review is aimed to make an overview of the biological aging research in Canada. I will summarize, to the best of my knowledge, the biological aging research undertaken actually in Canadian institutions dealing with various aspects of this research using many different experimental approaches, models from animals to humans and a huge array of techniques. The biological aging research is developing continuously in Canada, however, it is very important that we assist in a near future to its huge explosion if we would respond to the needs of an ever increasing aging population. Initiatives recently proposed by the Canadian government concerning the creation of Canadian Institutes on Health Research will provide good opportunities to establish a performant, cost-effective, and innovative biological aging research.