4-HDA Levels Research Articles

Long-term taurine administration improves motor skills in a tubulinopathy rat model by decreasing oxidative stress and promoting myelination

The taiep rat undergoes hypomyelination and progressive demyelination caused by an abnormal microtubule accumulation in oligodendrocytes, which elicits neuroinflammation and motor behavior dysfunction. Based on taurine antioxidant and proliferative actions, this work explored whether its sustained administration from the embryonic age to adulthood could prevent neuroinflammation, stimulate cell proliferation, promote myelination, and relieve motor impairment. Taurine (50 mg/L of drinking water = 50 ppm) was given to taiep pregnant rats on gestational day 15 and afterward to the male offspring until eight months of age. We measured the levels of nitric oxide (NO), malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA), CXCL1, CXCR2 receptor, growth factors (BNDF and FGF2), cell proliferation, and myelin content over time. Integral motor behavior was also evaluated. Our results showed that taurine administration significantly decreased NO and MDA + 4-HDA levels, increased cell proliferation, and promoted myelination in an age- and brain region-dependent fashion compared with untreated taiep rats. Taurine effect on chemokines and growth factors was also variable. Taurine improved vestibular reflexes and limb muscular strength in perinatal rats and fine movements and immobility episodes in adult rats. These results show that chronic taurine administration partially alleviates the taiep neuropathology.

Melatonin reduces high levels of lipid peroxidation induced by potassium iodate in porcine thyroid.

Iodine is essential for thyroid hormone synthesis. Under normal iodine supply, calculated physiological iodine concentration in the thyroid is approx. 9mM. Either potassium iodide (KI) or potassium iodate (KIO3) are used in iodine prophylaxis. KI is confirmed as absolutely safe. KIO3 possesses chemical properties suggesting its potential toxicity. Melatonin (N-acetyl-5-methoxytryptamine) is an effective antioxidant and free radical scavenger. Study aims: to evaluate potential protective effects of melatonin against oxidative damage to membrane lipids (lipid peroxidation, LPO) induced by KI or KIO3 in porcine thyroid. Homogenates of twenty four (24) thyroids were incubated in presence of either KI or KIO3 without/with melatonin (5mM). As melatonin was not effective against KI-induced LPO, in the next step only KIO3 was used. Homogenates were incubated in presence of KIO3 (200; 100; 50; 25; 20; 15; 10; 7.5; 5.0; 2.5; 1.25mM) without/with melatonin or 17ß-estradiol. Five experiments were performed with different concentrations of melatonin (5.0; 2.5; 1.25; 1.0; 0.625mM) and one with 17ß-estradiol (1.0mM). Malondialdehyde+4-hydroxyalkenals (MDA+4-HDA) concentration (LPO index) was measured spectrophotometrically. KIO3 increased LPO with the strongest damaging effect (MDA+4-HDA level: ≈1.28nmol/mg protein, p<0.05) revealed at concentrations of around 15mM, thus corresponding to physiological iodine concentrations in the thyroid. Melatonin reduced LPO (MDA+4-HDA levels: from ≈0.97 to ≈0,76 and from ≈0,64 to ≈0,49nmol/mg protein, p<0.05) induced by KIO3 at concentrations of 10mM or 7.5mM. Conclusion: Melatonin can reduce very strong oxidative damage to membrane lipids caused by KIO3 used in doses resulting in physiological iodine concentrations in the thyroid.

Melatonin protects against taurolithocholic‐induced oxidative stress in rat liver

Cholestasis, encountered in a variety of clinical disorders, is characterized by intracellular accumulation of toxic bile acids in the liver. Furthermore, oxidative stress plays an important role in the pathogenesis of bile acids. Taurolithocholic acid (TLC) was revealed in previous studies as the most pro-oxidative bile acid. Melatonin, a well-known antioxidant, is a safe and widely used therapeutic agent. Herein, we investigated the hepatoprotective role of melatonin on lipid and protein oxidation induced by TLC alone and in combination with FeCl(3) and ascorbic acid in rat liver homogenates and hepatic membranes. The lipid peroxidation products, malondialdehyde and 4-hydroxyalkenals (MDA + 4-HDA), and carbonyl levels were quantified as indices of oxidative damage to hepatic lipids and proteins, respectively. In the current study, the rise in MDA + 4-HDA levels induced by TLC was inhibited by melatonin in a concentration-dependent manner in both liver homogenates and in hepatic membranes. Melatonin also had protective effects against structural damage to proteins induced by TLC in membranes. These results suggest that the indoleamine melatonin may potentially act as a protective agent in the therapy of those diseases that involve bile acid toxicity.

Melatonin reduces Fenton reaction-induced lipid peroxidation in porcine thyroid tissue.

Free radicals and reactive oxygen species (ROS) participate in physiological and pathological processes in the thyroid gland. Bivalent iron cation (ferrous, Fe(2+)), which initiates the Fenton reaction (Fe(2+) + H2O2 --> Fe(3+) + *OH + OH(-)) is frequently used to experimentally induce oxidative damage, including that caused by lipid peroxidation. Lipid peroxidation is involved in DNA damage, thus indirectly participating in the early steps of carcinogenesis. In turn, melatonin is a well-known antioxidant and free radical scavenger. The aim of the study was to estimate the effect of melatonin on basal and iron-induced lipid peroxidation in homogenates of the porcine thyroid gland. In order to determine the effect of melatonin on the auto-oxidation of lipids, thyroid homogenates were incubated in the presence of that indoleamine in concentrations of 0.0, 0.00001, 0.0001, 0.001, 0.01, 0.1, 0.25, 0.5, 1.0, 2.5, or 5.0 mM. To study melatonin effects on iron-induced lipid peroxidation, the homogenates were incubated in the presence of FeSO(4) (40 microM) plus H2O2 (0.5 mM), and, additionally, in the presence of melatonin in the same concentrations as above. The degree of lipid peroxidation was expressed as the concentration of malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) per mg protein. Melatonin, in a concentration-dependent manner, decreased lipid peroxidation induced by Fenton reaction, without affecting the basal MDA + 4-HDA levels. In conclusion, melatonin protects against iron + H2O2-induced peroxidation of lipids in the porcine thyroid. Thus, the indoleamine would be expected to prevent pathological processes related to oxidative damage in the thyroid, cancer initiation included.

Role of exogenous melatonin in reducing the nephrotoxic effect of daunorubicin and doxorubicin in the rat.

The aim of these studies was to examine the nephroprotective effect of melatonin following the anthracycline administration [daunorubicin (DNR); doxorubicin (DOX)] in rats. Application of these drugs in chemotherapy is limited because of their cardiotoxicity and nephrotoxicity. Rats of the Buffalo strain were divided into groups according to the cytostatic drug used, its dose and sequence of administration [DNR or DOX single (i.v.) dose of 10 mg/kg b.w., i.e. acute intoxication and 3 mg/kg b.w. (i.v.) weekly for 3 wk, subchronic intoxication]. Melatonin was administered subcutaneously before and after every injection of a cytostatic drug at a dose of 10 mg/kg b.w. The severity of renal alterations was examined both biochemically [levels of lipid peroxidation markers, malonyldialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)], or histologically. A statistically significant decrease in renal damage was noted after melatonin administration to acutely or subchronically intoxicated DNR-treated and DOX-treated rats. Biochemical assays revealed significant decreases in MDA and 4-HDA levels following application of melatonin during subchronic DNR or DOX intoxication. In summary, melatonin was found to exert a protective effect on the kidney, which was particularly evident after subchronic DOX and DNR intoxication, using both histological or biochemical methods.

Melatonin reduces phosphine-induced lipid and DNA oxidation in vitro and in vivo in rat brain.

Phosphine (PH(3)), a widely used pesticide, was found in our recent study to induce oxidative damage in the brain, liver and lung of rats. We also observed that melatonin significantly blocked this action. The present study focused on brain and the magnitude and mechanism of protection of PH(3)-induced oxidative damage by melatonin in vitro and in vivo. PH(3) in whole brain homogenate (3 mg protein/mL Tris-HCl pH 7.4 buffer) induced increasing lipid peroxidation [as malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)] dependent on concentration (0.25-2 mM) and time (30-150 min), reaching a maximum level of 2.9-fold at 90 min after PH(3) at 1 mM. Elevation of MDA + 4-HDA levels by PH(3) at 1 mM was also observed in homogenates of cerebral cortex, cerebellum, hippocampus and hypothalamus examined individually. Melatonin at 0.1-2 mM progressively inhibited PH(3)-induced lipid peroxidation in brain and regions thereof. Additionally, PH(3) induced brain DNA oxidation in vitro and in vivo determined as 8-hydroxyguanosine (8-OH-dG). Melatonin at 1 mM significantly suppressed PH(3)-induced brain DNA oxidation in vitro. PH(3) at 4 mg/kg i.p. significantly elevated 8-OH-dG in frontal cortex and melatonin prevented it. PH(3) in vivo marginally lowered brain glutathione peroxidase activity and melatonin restored it completely. In contrast, PH(3) and melatonin both stimulated superoxide dismutase production. Brain glutathione (GSH) levels in PH(3)-treated rats were significantly reduced at 30 min and recovered gradually. It is concluded that melatonin, probably because of its free radical scavenging ability, confers marked protection against PH(3)-induced oxidative toxicity in brain.

Relative efficacies of indole antioxidants in reducing autoxidation and iron-induced lipid peroxidation in hamster testes.

Increased iron stores are associated with free radical generation and carcinogenesis. Lipid peroxidation is involved in DNA damage, thus indirectly participating in the early steps of tumor initiation. Melatonin and structurally related indoles are effective in protecting against oxidative stress. The aim of the study was to compare the relative efficacies of melatonin, N-acetylserotonin (NAS), indole-3-propionic acid (IPA), and 5-hydroxy-indole-3-acetic acid (5HIAA) in altering basal and iron-induced lipid peroxidation in homogenates of hamster testes. To determine the effect of the indoles on the autoxidation of lipids, homogenates were incubated in the presence of each agent in concentrations of 0.0, 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 2.0, 2.5, or 5.0 mM. To study their effects on induced lipid peroxidation, homogenates were incubated with FeSO(4) (30 microM + H(2)O(2) (0.1 mM) + each of the indoles in the same concentrations as above. The degree of lipid peroxidation was expressed as concentrations of malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) per mg protein. The indoles decreased both basal and iron-related lipid peroxidation in a concentration-dependent manner. Melatonin reduced basal MDA + 4-HDA levels when used at the concentrations of 0.25 mM or higher, and prevented iron-induced lipid peroxidation at concentrations of 1.0, 2.0, 2.5, or 5.0 mM. The lowest effective concentrations of NAS required to lower basal and iron-related lipid peroxidation were 0.05 mM and 0.25 mM, respectively. IPA, only when used in the highest concentrations of 2.5 mM or 5 mM inhibited basal lipid peroxidation levels and it was ineffective on the levels of MDA + 4-HDA due to iron damage. 5HIAA reduced basal lipid peroxidation when used at concentrations of 0.25 mM or higher, and it prevented iron-induced lipid peroxidation only at the highest applied concentration (5 mM). In conclusion, melatonin and related indoles at pharmacological concentrations protect against both the autoxidation of lipids as well as induced peroxidation of lipids in testes. In doing so, these agents would be expected to reduce testicular cancer that is initiated by products of lipid peroxidation.

Role of melatonin in reduction of lipid peroxidation and peroxynitrite formation in non-septic shock induced by zymosan.

Zymosan, a non-bacterial agent, causes inflammation by inducing the production of a variety of cytokines and pro-inflammatory mediators, wherein reactive oxygen species including nitric oxide and peroxynitrite are known to play a crucial role in the inflammatory process. The current study was designed to investigate the protective effect of melatonin, a radical scavenger and antioxidant, on non-septic shock induced by zymosan in the rat. Four groups of rats (controls, melatonin-injected [5 mg/kg x 6], zymosan-injected [500 mg/kg], and zymosan + melatonin) were used in this experiment. Thiobarbituric acid reactive substances (malondialdehyde [MDA] + 4-hydroxyalkenals [4-HDA]), as an index of lipid peroxidation, were measured in the liver, lung, small intestine (ileum), kidney and pancreas. Twenty-four hours after zymosan administration, MDA + 4-HDA levels were significantly increased in the liver, lung, small intestine, and kidney while the increase in the pancreas was not statistically significant compared to levels in control rats. The percentage increases in lipid peroxidation products were 34.3%, 39.2%, 48.5%, 32.5%, and 17.4% for the liver, lung, small intestine, kidney, and pancreas, respectively. In animals given melatonin 30 minutes before zymosan, and 5 more times after zymosan (i.e., every 4 hours), the increase in MDA + 4-HDA levels was reduced in all organs studied. There was also a significant increase in the volume of peritoneal exudate in zymosan-treated rats that was reduced when the zymosan-shocked rats received melatonin. After zymosan administration, immunohistochemical and histological examination demonstrated a marked increase in the immunoreactivity to nitrotyrosine, a specific "footprint" of peroxynitrite, and tissue damage in the liver, lung, and small intestine of zymosan-shocked rats. Again, melatonin treatment reduced both nitrotyrosine immunoreactivity and tissue damage associated with zymosan administration.

Inhibitory effect of melatonin on products of lipid peroxidation resulting from chronic ethanol administration.

Despite decades of research, the role of free radicals in alcohol-induced organ injury is still a matter of debate. The present work was designed to investigate the potential protective effect of melatonin, a reported radical scavenger and antioxidant, on free radical toxicity induced by chronic ethanol administration. The major end-point of oxidative damage measured in this report was lipid peroxidation. Four groups of male Sprague-Dawley rats were used. The first group served as untreated controls and received a daily injection of alcoholic (<1% ethanol) saline. The second group of rats received daily at 18:00 a single subcutaneous injection of melatonin (10 mg/kg). Group 3 rats received only ethanol (3 g/kg) for 30 consecutive days; the ethanol was given at 18:30. The final group of rats was given both melatonin and ethanol with melatonin preceding ethanol by 30 min. Products of lipid peroxidation [malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)] were measured in the brain, heart, liver, lung and testes. At the conclusion of the study, MDA + 4-HDA levels were significantly increased in brains, hearts, lungs and testes, but not livers, of alcohol-treated compared with control rats. The percentage increases in lipid peroxidation products were 21.8%, 28.8%, 35.9% and 45.3% for brain, heart, lung and testes, respectively. In animals given melatonin 30 min before ethanol, the increases in MDA + 4-HDA levels were significantly reduced in all organs investigated, with levels not different from those in control rats. Based on these findings, it is speculated that melatonin's direct and indirect antioxidative actions inhibited alcohol-induced lipid peroxidation. These results suggest a new strategy for the treatment of alcohol-related diseases using melatonin as an antioxidant to reduce the damage inflicted by aggressive radical species.

Melatonin enhances tamoxifen's ability to prevent the reduction in microsomal membrane fluidity induced by lipid peroxidation.

The indoleamine melatonin and the synthetic antiestrogenic drug tamoxifen seem to have similar mechanisms in inhibiting the growth of estrogen receptor positive breast cancer cells. In this study, we compared the ability of these molecules, alone and in combination, in stabilizing microsomal membranes against free radical attack. Hepatic microsomes were obtained from male rats and incubated with or without tamoxifen (50-200 microM), melatonin (1 mM) or both; lipid peroxidation was induced by addition of FeCl3, NADPH and ADP. After oxidative damage, membrane fluidity, measured by fluorescence polarization techniques, decreased whereas malonaldehyde (MDA) and 4-hydroxyalkenals (4-HDA) concentrations increased. Incubation of the microsomes with tamoxifen prior to exposure to free radical generating processes inhibited, in a dose-dependent manner, the increase in membrane rigidity and the rise in MDA + 4-HDA levels. When melatonin was added, the efficacy of tamoxifen in preventing membrane rigidity was enhanced. Thus, the IC50s for preventing membrane rigidity and for inhibiting lipid peroxidation obtained for tamoxifen in the presence of melatonin were lower than those obtained with tamoxifen alone. Moreover, tamoxifen (50-200 microM) in the presence of melatonin reduced basal membrane fluidity and MDA + 4-HDA levels in microsomes. These synergistic effects of tamoxifen and melatonin in stabilizing biological membranes may be important in protecting membranes from free radical damage.

Effect of melatonin, piperonyl butoxide, or cobalt chloride on l-cysteine-induced lipid peroxidation in homogenate from whole brain of mice

Brain homogenates exposed to a low concentration of l-cysteine (0.05, 0.1, 0.5, 1.0, and 2.0 mM) were significantly increased in their concentration of malondialdehyde (MDA) + 4-hydroxyalkenals (4-HDA) as compared to control samples, in a concentration-dependent manner. The increased lipid peroxidation by l-cysteine was attenuated or completely abolished by co-incubation with melatonin (2 mM), a potent free radical scavenger, piperonyl butoxide (1 mM), an inhibitor of mixed function oxidase, or cobalt chloride (0.01, 0.02 or 0.05 mM), another inhibitor of mixed function oxidase, but not allopurinol (0.1 mM), an inhibitor of xanthine oxidase. In addition, when a brain homogenate heated at 85 °C for 1 min was incubated with or without l-cysteine at 37 °C for 20 min, MDA + 4-HDA levels in the homogenate was not changed between l-cysteine and control. These results suggest that l-cysteineinduced lipid peroxidation may be involved in the enzymatic mixed function oxidation systems in brain.

Paraquat toxicity and oxidative damage: Reduction by melatonin

The ability of melatonin to protect against paraquat-induced oxidative damage in rat lung, liver, and serum was examined. Changes in the levels of malondialdehyde (MDA) plus 4-hydroxyalkenals (4-HDA) and reduced and oxidized glutathione concentrations were measured. Paraquat (50 mg/kg) was injected i.p. into either Sprague-Dawley or Wistar rats with or without the co-administration of 5 mg/kg melatonin. Paraquat alone increased MDA + 4-HDA levels in serum and lungs of both rat strains, with these increases being abolished by melatonin co-treatment. Paraquat also decreased reduced glutathione levels and increased oxidized glutathione concentrations in lung and liver; these changes were negated by melatonin. The effect of melatonin on paraquat-induced mortality was also studied. Paraquat at a dose of 79 mg/kg was lethal for 50% of animals within 24 hr; when administered together with melatonin, the LD 50 for paraquat increased to 251 mg/ kg.

Melatonin reduces both basal and bacterial lipopolysaccharide-induced lipid peroxidation in vitro

The protective effect of melatonin against lipopolysaccharide (LPS)-induced oxidative damage was examined in vitro. Lung, liver, and brain malonaldehyde (MDA) plus 4-hydroxyalkenals (4-HDA) concentrations were measured as indices of induced membrane peroxidative damage. Homogenates of brain, lung, and liver were incubated with LPS at concentrations of either 1, 10, 50, 200, or 400μg/ml for 1 h and, in another study, LPS at a concentration of 400 μg/ml for either 0, 15, 30, or 60 min. Melatonin at increasing concentrations from 0.01–3 mM either alone or together with LPS (400μg/ml) was used. Liver, brain, and lung MDA + 4-HDA levels increased after LPS at concentrations of 10, 50, 200 or 400 μg/ml; this effect was concentration-dependent. The highest levels of lipid peroxidation products were observed after tissues were incubated with an LPS concentration of 400 μg/ml for 60 min; in liver and lung this effect was totally suppressed by melatonin and partially suppressed in brain in a concentration-dependent manner. In addition, melatonin alone was effective in brain at concentrations of 0.1 to 3 mM, in lung at 2 to 3 mM, and in liver at 0.1 to 3 mM; in all cases, the inhibitory effects of melatonin on lipid peroxidation were always directly correlated with the concentration of melatonin in the medium. The results show that the direct effect of LPS on the lipid peroxidation following endotoxin exposure is markedly reduced by melatonin.

Melatonin reduces H2O2‐induced lipid peroxidation in homogenates of different rat brain regions

The ability of melatonin to modify H2O2-induced lipid peroxidation in brain homogenates was determined. The concentrations of brain malonaldehyde (MDA) and 4-hydroxyalkenals (4-HDA) were assayed as an index of induced membrane oxidative damage. Homogenates from five different regions of the brain (cerebral cortex, cerebellum, hippocampus, hypothalamus, and corpus striatum) derived from two different strains of rats, Sprague-Dawley and Wistar, were incubated with either H2O2 (5 mM) alone or H2O2 together with melatonin at increasing concentrations ranging from 0.1 to 4 mM. The basal level of lipid peroxidation was strain-dependent and about 100% higher in homogenates from the brain of Wistar rats than those measured in Sprague-Dawley rats. MDA + 4-HDA levels increased after H2O2 treatment in homogenates obtained from each region of the brain in both rat strains but the sensitivity of the homogenates from Sprague-Dawley rats was greater than that for the homogenates from Wistar rats (increases after H2O2 from 45 to 165% compared 20 to 40% for Sprague-Dawley and Wistar rats, respectively). Melatonin co-treatment reduced H2O2-induced lipid peroxidation in brain homogenates in a concentration-dependent manner; the degree of protection against lipid peroxidation was similar in all brain regions.