Enhanced in vivo lipid peroxidation at elevated plasma total homocysteine levels.

An elevated plasma total homocysteine level (tHcy) is considered an independent risk factor for atherosclerosis. The mechanisms by which hyperhomocysteinemia induces atherosclerosis are only partially understood, but promotion of LDL oxidation and endothelial injury have been suggested. The purpose of this study was to test the hypothesis that a high plasma tHcy is associated in men with increased in vivo lipid peroxidation, as measured by plasma F2-isoprostane concentrations. We investigated this association in a subset of the participants in the Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) study. Of 256 male participants, a subsample of 100 consecutive men was selected for F2-isoprostane assays. The mean tHcy was 11.0 micromol/L, and the mean F2-isoprostanes was 29.6 ng/L. The simple correlation coefficient for association between tHcy and F2-isoprostane was 0.40 (P<0.001). In a linear regression model, the variables with the strongest associations with F2-isoprostane were tHcy (standardized coefficient 0.33, P<0.001), serum triglycerides (0.21, P=0.042), carbohydrate-deficient transferrin (0.15, P=0.132), and plasma lipid-standardized alpha-tocopherol (-0.11, P=0.252) (R2=0.24, P<0. 001 for model). Plasma F2-isoprostane levels increased linearly across quintiles of tHcy (P<0.001). The unadjusted mean (95% confidence interval) F2-isoprostanes was 47.5% greater in the highest tHcy quintile (37.4, 31.1 to 43.6 ng/L) than in the lowest quintile (25.3, 21.3 to 29.3 ng/L). Adjustment for the strongest other determinants of F2-isoprostane reduced this difference to 28. 2% (P=0.010). Our present data suggest that elevated fasting plasma tHcy is associated with enhanced in vivo lipid peroxidation in men.

Coenzyme Q10 supplementation and recovery from ischemia in senescent rat myocardium.

Many studies have suggested that parenteral administration of coenzyme Q10 (Q10) protects the myocardium of young experimental animals from post-ischemic reperfusion injury. Although parenteral administration, in contrast to per os supplementation, seems to elevate coenzyme Q concentrations in heart tissue, it is not suitable for prophylactic use. In addition, the incidence of ischemic events is greatest in older age. We studied the effect of Q10 supplementation on myocardial postischemic recovery in 18-month-old Wistar rats. The treated group (n=9) received 10 mg/kg/day of Q10 for 8 weeks in their chow while the normal chow of the control group (n=9) contained less than 0.5 mg/kg/day of Q10. The treatment clearly elevated plasma Q10 concentration (286 +/- 25 micromol/l and 48 +/- 30 micromol/l, treated and controls, respectively, p<0.0001) but neither Q9 nor Q10 concentrations in heart tissue were affected by the supplementation. The isolated perfused hearts were subjected to 20 minutes of ischemia and 30 minutes of reperfusion. The preischemic values of developed pressure (DP) but not contractility (+DP/delta t) and relaxation (-DP/delta t) were improved by Q10 supplementation (p=0.034, p=0.057 and p=0.13, respectively) while in postischemic recovery no differences were observed between the groups (p>0.05 at all time points). Also, in myocardial flow, myocardial oxygen consumption (MVO2) and myocardial aerobic efficiency (DP/MVO2) the groups did not differ at any time points. Although dietary Q10 supplementation clearly elevated plasma Q10 concentrations in senescent rats, the coenzyme Q contents in heart tissue and myocardial recovery from ischemia were not affected. However, it is possible that the site of action for the reported beneficial effects of Q10 is in the coronary endothelium rather than myocardium itself.

Control of arterial tone after long-term coenzyme Q10 supplementation in senescent rats.

1. Age-associated deterioration of arterial function may result from long-lasting oxidative stress. Since coenzyme Q (Q10) has been suggested to protect the vascular endothelium from free radical-induced damage, we investigated the effects of long-term dietary Q10 supplementation on arterial function in senescent Wistar rats. 2. At 16 months of age, 18 rats were divided into two groups. The control group was kept on a standard diet while the other group was supplemented with Q10 (10 mg kg(-1) day(-1)). In addition, nine rats (age 2 months) also ingesting a standard diet were used as the young control group. After 8 study weeks the responses of the mesenteric arterial rings in vitro were examined. 3. Endothelium-independent arterial relaxations to isoprenaline and nitroprusside (SNP) were attenuated in aged rats. Increased dietary Q10 clearly enhanced the relaxation to isoprenaline, but did not affect the response to SNP. In addition, vasodilation of noradrenaline-precontracted rings to acetylcholine (ACh), which was also impaired in aged vessels, was improved after Q10 supplementation. Cyclooxygenase inhibition with diclofenac enhanced the relaxation to ACh only in young rats, while it abolished the difference between the old controls and Q10 supplemented rats, suggesting that the improved endothelium-dependent vasodilation observed in Q10 supplemented rats was largely mediated by prostacyclin (PGI2). 4. In conclusion, long-term Q10 supplementation improved endothelium-dependent vasodilation and enhanced beta-adrenoceptor-mediated arterial relaxation in senescent Wistar rats. The mechanisms underlying the improvement of endothelial function may have included augmented endothelial production of PGI2, increased sensitivity of smooth muscle to PGI2, or both.

The effects of lifelong ubiquinone Q10 supplementation on the Q9 and Q10 tissue concentrations and life span of male rats and mice.

The effect of lifelong oral supplementation with ubiquinone Q10 (10 mg/kg/day) was examined in Sprague-Dawley rats and C57/B17 mice. There were no significant differences in survival or life-span found in either rats or mice. Histopathologic examination of different rat tissues showed no differences between the groups. In Q10 supplemented rats, plasma and liver Q10 levels were 2.6 to 8.4 times higher at all age points than in control rats. Interestingly, in supplemented rats the Q9 levels also were significantly higher (p<0.05) in plasma and liver at ages 18 and 24 months. Neither Q9 nor Q10 levels were affected by supplementation in kidney, heart, or brain tissues. In spite of the significant changes in plasma and liver ubiquinone concentrations, lifelong Q10 supplementation did not prolong or shorten the lifespan of either rats or mice.

Ubiquinol-10 and total peroxyl radical trapping capacity of LDL lipoproteins during aging: the effects of Q-10 supplementation.

Evidence is rapidly accumulating that oxidative modification of low density lipoprotein (LDL) may play an important role in the pathogenesis of atherosclerosis. In this study we measured the total peroxyl radical trapping capacity of human plasma LDL phospholipids (TRAPLDL) with a luminescent method. The study was carried out with 70 healthy volunteers, aged 28-77. In males an age-related decrease in TRAPLDL was observed. In the age group under 50 years the mean TRAPLDL was 31.36 +/- 1.45 pmol peroxyl radicals/nmol Pi; among those over 50 years it was significantly lower at 26.67 0.94 pmol/nmol Pi. As regards the components of TRAPLDL, the concentration of LDL-ubiquinol did not change and a non-significant decrease in the LDL-tocopherol concentration was detected with age. In females, the mean TRAPLDL, LDL-ubiquinol-10 and tocopherol concentrations did not differ between the age groups. When 17 of the participants were given coenzyme Q10 (Q10) supplementation, 100 mg/day, a highly significant increase in LDL-ubiquinol concentration was detected. Our results indicate that LDL antioxidant defenses tend to decrease with age in the Finnish male population. The decline is most significant in males under 50 years; in older age groups the values remain stable at a low level. Q10 supplementation doubles the number of ubiquinol-10-containing LDL molecules and may therefore have an inhibitory effect on LDL oxidation.

The effect of ascorbate and ubiquinone supplementation on plasma and CSF total antioxidant capacity.

Free radicals are thought to be involved in the onset of neuronal disturbances such as Alzheimer's disease, Parkinson's disease, and neuronal ceroid lipofuscinosis. It is also assumed that they play a role in cerebral injury caused by ischemia or trauma. Plasma and cerebrospinal fluid (CSF), Total (peroxyl) Radical-trapping Antioxidant Parameter (TRAP), and the known antioxidant components of TRAP, for instance, ascorbic acid, uric acid, protein sulfhydryl groups, tocopherol, and ubiquinol were analyzed and the remaining unidentified fragment was calculated in five healthy volunteers before and after 4 weeks of ascorbate and ubiquinone (Q-10) supplementation. In CSF, TRAP was significantly lower than in plasma. The major contributor to plasma's antioxidant capacity was uric acid (UA), whereas in CSF it was ascorbic acid (AA). In CSF, AA concentrations were four times higher than in plasma. Oral supplementation of AA (500 mg/d first 2 weeks, 1,000 mg/d following 2 weeks) and Q-10 (100 mg/d first 2 weeks, 300 mg/d following 2 weeks) induced a significant increase in plasma AA and Q-10. Surprisingly, in spite of the high lipophilicity of Q-10, its concentration did not change in CSF. The supplementation of AA increased its concentration in CSF by 28% (p < .05). However, the increase in AA did not result in an increase in CSF TRAP. This indicates that AA had lost one-third of its radical trapping capacity as compared to that in plasma. The facts that AA is the highest contributor to CSF TRAP and its effect on TRAP is concentration dependent could indicate that the peroxyl radical-trapping capacity of CSF is buffered by AA.

The role of coenzyme Q-10 in aging: a follow-up study on life-long oral supplementation Q-10 in rats.

The essential role of coenzyme Q--ubiquinone--in biological energy transduction is well established. Reduced Q--ubiquinol--has also been shown to act as an antioxidant and to decrease the action of free radicals, which in turn could cause damage to structural lipids or proteins. The accumulation of lipopigments during aging in several peripheral organs and in the nervous system is considered to be related to the peroxidation of unsaturated fatty acids. An age-related decline of Q-10 has been suggested to occur in man and rats. In this study we followed the effects of life-long oral supplementation of coenzyme Q-10 on the development and life-span and pigment accumulation in peripheral tissues and the nervous system of laboratory rats. The Q-10 supplemented group showed a significant increase in Q-10 in plasma and liver, while it was unchanged in other tissues. There was no significant difference between the two groups in the development and mortality of the animals. No differences were observed in lipopigment accumulation. Our results indicate that in rats, life-long supplementation of Q-10 has no beneficial effects on life-span or pigment accumulation.

Relaxation training combined with increased physical activity lowers the psychophysiological activation in community-home boys.

Resting electrical activity (EMG) in the frontalis, temporalis, trapezius and erector trunci muscles, as well as systolic and diastolic blood pressure (BP), were measured in boys in a community home, and in controls of the same age in an ordinary school. EMG in the community-home boys was significantly higher than in controls, whereas BP did not yield any difference. The community-home boys participated in a programme consisting of relaxation training and increased physical activity for 4 months. After this intervention, EMG in all muscle groups was decreased, and the level of EMG was also lower than the values measured in controls. Systolic and diastolic BP in the community-home boys was also lowered, but the decrease was not significant as compared to the control group. In conclusion, relaxation training and/or increased physical activity is effective in decreasing the elevated activation observed in community-home boys.

Effect of vitamin E and selenium supplement on the aging peripheral neurons of the male Sprague-Dawley rat.

The effect of life-long diets containing different concentrations of selenium and vitamin E on the age pigment accumulation in the rat superior cervical ganglion, vagal ganglion and dorsal root ganglion, was studied using microspectrofluorometry. All types of ganglia showed unchanged amounts of age pigments at low or high concentrations of selenium, whereas dietary concentration of vitamin E regulated age pigment content in the dorsal root ganglion, but not in the superior cervical and vagal ganglion. Vitamin E deficiency induced a three-fold increase in age pigment content in dorsal root ganglion at 8 months of age, whereas high vitamin E concentration was associated with a lesser amount of pigments at 18 months of age. Emission spectra of age pigment recorded from the dorsal root ganglion and vagal ganglion were different from that from the superior cervical ganglion, but were independent of dietary concentrations of selenium or vitamin E. The results suggest that exogenous antioxidants may play a more crucial role in lipid peroxidation and accumulation of age pigment in dorsal root ganglion than in autonomic ganglia.

Effect of lifelong selenium and vitamin E deficiency or supplementation on pigment accumulation in rat peripheral tissues.

The accumulation of lipopigments during aging in several peripheral organs and in the nervous system is considered to be related to the peroxidation of unsaturated fatty acids. In this study the effect of lifelong (until to 18 months) dietary antioxidants selenium and vitamin-E on pigment accumulation in some peripheral tissues was estimated using fluorescence and electron microscopy. In the vitamin E deficiency group, there was increased pigment accumulation in all peripheral tissues studied except the hypogastric ganglion, where no change was observed. The vitamin E supplementation degreased the pigment accumulation in older animals in some of the tissues studied. At the electron microscopical level the accumulated pigment in the adrenal cortex showed a lipofuscin-like structure. Lifelong selenium supplementation or deficiency did not significantly alter pigment accumulation in any of the tissues studied. It is possible that in many organs dietary selenium may not play a critical role in lipofuscin formation.

Subcellular location and neuronal release of diazepam binding inhibitor.

Diazepam binding inhibitor (DBI), a peptide located in CNS neurons, blocks the binding of benzodiazepines and beta-carbolines to the allosteric modulatory sites of gamma-aminobutyric acid (GABAA) receptors. Subcellular fractionation studies of rat brain indicate that DBI is compartmentalized. DBI-like immunoreactivity is highly enriched in synaptosomes obtained by differential centrifugation in isotonic sucrose followed by a Percoll gradient. In synaptosomal lysate, DBI-like immunoreactivity is primarily associated with synaptic vesicles partially purified by differential centrifugation and continuous sucrose gradient. Depolarization induced by high K+ levels (50 mM) or veratridine (50 microM) released DBI stored in neurons of superfused slices of hypothalamus, hippocampus, striatum, and cerebral cortex. The high K+ level-induced release is Ca2+ dependent, and the release induced by veratridine is blocked by 1.7 microM tetrodotoxin. Depolarization released GABA and Met5-enkephalin-Arg6-Phe7 together with DBI. DBI is also released by veratridine depolarization, in a tetrodotoxin-sensitive fashion, from primary cultures of cerebral cortical neurons, but not from cortical astrocytes. Depolarization fails to release DBI from slices of liver and other peripheral organs. These data support the view that DBI may be released as a putative neuromodulatory substance from rat brain neurons.

Studies of a brain polypeptide functioning as a putative endogenous ligand to benzodiazepine recognition sites in rats selectively bred for alcohol related behavior.

The brain content of Diazepam Binding Inhibitor (DBI), its cell location and that of its specific mRNA were studied immunohistochemically and by in situ hybridization. Various strains of rats were genetically selected for their alcohol tolerance and the above mentioned brain parameters were studied before and after chronic ethanol consumption. The DBI like immunoreactivity (DBI-LI) was found to be located in selected neuronal population and in non-neuronal cells. The DBI-mRNA was located in brain areas where DBI is abundant. It was immunochemically determined that the DBI content was increased in cerebellum and in hypothalamus of alcohol preferring rats after chronic ethanol consumption. DBI content was compared in the cerebellum of rats genetically selected for different alcohol sensitivity and it was significantly higher on the ethanol sensitive (ANT) rat strain.

Diazepam-binding inhibitor: a neuropeptide located in selected neuronal populations of rat brain.

An endogenous polypeptide of rat brain has been identified that is capable of displacing 1,4-benzodiazepines and the esters of the 3-carboxylic acid derivatives of beta-carbolines from their specific synaptic binding sites. This polypeptide was termed diazepam-binding inhibitor (DBI). Previous studies have shown that DBI injected intraventricularly in rodents elicits "proconflict" responses and antagonizes the "anticonflict" action of benzodiazepines. An antiserum to this peptide, directed toward an immunodeterminant near its amino terminus, makes it possible to detect, measure, and study the neuronal location of this peptide in rat brain. In the rat cerebral cortex, DBI immunoreactivity is located in neurons that are not GABAergic (GABA, gamma-aminobutyric acid); in the cerebellum and hippocampus, however, it might be present also in GABAergic neurons.