DNA Damage In Organs Research Articles

Effect of Methanolic Extract of Justicia Flava on Petroleum-Induced Reduced Cell Division and DNA Damage

The objective of this research was to determine the import of Justicia flava methanolic extract against petroleum-stimulated reduced cell division and DNA fragmentation.
 Materials and Methods. Ninety rats were distributed and treated as follows for thirty days: Group A - normal diet; Group B - normal feed + 100mg/kg bwt of Justicia flava methanolic extract; Group C - normal feed + 200mg/kg bwt of Justicia flava methanolic extract; Group D - normal feed + 300mg/kg bwt of Justicia flava methanolic extract; Group E - normal feed + 250 mg/kg bwt of standard ascorbic acid; Group F - crude oil-tainted feed; Group G - crude oil-tainted feed + 250 mg/kg bwt of standard ascorbic acid; Group H - crude oil-tainted feed + 100mg/kg bwt of Justicia flava methanolic extract; Group I - crude oil-tainted feed + 200mg/kg bwt of Justicia flava methanolic extract. After thirty days, the rats were sacrificed under chloroform sedation and the liver and kidney were collected for cellular analysis via standard protocols.
 Results. The results showed that administration of Justicia flava methanolic extract decreased petroleum-induced reduced cell division and DNA damage in the liver and kidney of experimental rats. Justicia flava methanolic extract is potent antidote for petroleum-induced DNA damage in the liver and kidney of rats.
 Conclusions. It is no doubt that ingestion of petroleum-tainted diet could culminate in DNA damage in organs and tissues of animals. However, the administration of Justicia flava methanolic extract was found to prevent this damage in renal and liver cells of experimental rats.

Optimal dose selection of N-methyl-N-nitrosourea for the rat comet assay to evaluate DNA damage in organs with different susceptibility to cytotoxicity

The in vivo rodent alkaline comet assay (comet assay) is a promising technique to evaluate DNA damage in vivo. However, there is no agreement on a method to evaluate DNA damage in organs where cytotoxicity is observed. As a part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the comet assay, we examined DNA damage in the liver, stomach, and bone marrow of rats given three oral doses of N-methyl-N-nitrosourea (MNU) up to the maximum tolerated dose based on systemic toxicity. MNU significantly increased the % tail DNA in all the organs. Histopathological analysis showed no cytotoxic effect on the liver, indicating clearly that MNU has a genotoxic potential in the liver. In the stomach, however, the cytotoxic effects were very severe at systemically non-toxic doses. Low-dose MNU significantly increased the % tail DNA even at a non-cytotoxic dose, indicating that MNU has a genotoxic potential also in the stomach. Part of the DNA damage at cytotoxic doses was considered to be a secondary effect of severe cell damage. In the bone marrow, both the % tail DNA and incidence of micronucleated polychromatic erythrocytes significantly increased at non-hematotoxic doses, which were different from the non-cytotoxic doses for liver and stomach. These findings indicate that an optimal dose for detecting DNA damage may vary among organs and that careful attention is required to select an optimum dose for the comet assay based on systemic toxicity such as mortality and clinical observations. The present study shows that when serious cytotoxicity is suggested by increased % hedgehogs in the comet assay, histopathological examination should be included for the evaluation of a positive response.

DNA damage in organs of female and male mice exposed to nonylphenol, as a single agent or in combination with ionizing irradiation: A comet assay study

The effect of nonylphenol (NP; either alone or in combination with ionizing radiation) on the induction of DNA strand breaks in mouse somatic cells has been examined. Male and female mice were repeatedly irradiated with X-rays (0.05 or 0.10Gy), injected with NP (25 or 50mg/kg bw), or both (0.05Gy+25mg/kg bw NP or 0.10Gy+50mg/kg bw NP), for 2 weeks, 5 days/week. Liver, spleen, femora, lungs and kidneys were removed from each animal for the comet assay. NP-induced DNA damage differed, depending on organ and sex. In male mice, NP induced damage in all organs examined; in females, only the kidneys were affected. The effect of irradiation alone was similar in females and males. Combined exposure of males to 0.05Gy+25mg/kg bw NP significantly reduced the level of DNA strand breaks, compared to the controls and to 25mg/kg bw NP alone, in the majority of organs. The higher doses significantly increased damage to DNA in all organs examined. Combined exposure of females to low doses of both agents significantly enhanced damage to DNA in bone marrow lymphocytes and in cells of the liver and kidneys, compared to controls. At 0.10Gy+50mg/kg bw NP, DNA damage was increased in organs except liver and spleen. Although NP alone may not be mutagenic in female mice, its co-administration with irradiation may increase DNA damage in some organs. In contrast, in male mice, damage was reduced after combined irradiation-NP exposure, compared to NP alone.

DNA damage in organs of mice treated acutely with patulin, a known mycotoxin

Patulin, a known mycotoxin, is considered a significant contaminant in apples, apple-derived products and feeds. This study investigated the genotoxic effects of patulin in multiple organs (brain, kidney, liver and urinary bladder) of mice using an in vivo comet assay. We assessed the mechanism underlying this genotoxicity by measuring the GSH content and the thiobarbituric acid-reactive species (TBARS) level. Male CF-1 mice were given 1.0–3.75mg/kg patulin intraperitoneally. The effect of patulin was dose-dependent and the highest patulin dose induced DNA strand breaks in the brain (damage index, DI, in hippocampus increased from 36.2 in control animals to 127.5), liver (44.3–138.4) and kidneys (31.5–99); decreased levels of GSH (hippocampus – from 46.9 to 18.4nmol/mg protein); and an increase in lipid peroxidation (hippocampus – from 5.8 to 20.3 MDA equivalents/mg protein). This finding establishes an interrelationship between the pro-oxidant and genotoxic effects of patulin. Pre-treatment administration of N-acetyl-cysteine reduced patulin-induced DNA damage (hippocampus – DI from 127.5 to 39.8) and lipid peroxidation (hippocampus – 20.3 to 12.8 MDA equivalents/mg protein) by restoring cellular GSH levels, reinforcing the positive relationship between patulin-induced GSH depletion and DNA damage caused by systemic administration of this mycotoxin.

DNA and oxidative damage induced in somatic organs and tissues of mouse by municipal sludge leachate

Pollution by waste landfill leachate has prompted a number of studies on the toxic and potential health effects. This study assessed the genotoxicity of a municipal sludge leachate (MSL) in the somatic tissues (blood and bone marrow) and organs (liver, kidney, and spleen) of mice using the alkaline Comet assay. The possible cause of DNA damage via the study of antioxidant system (lipid peroxidation [LPO]; catalase [CAT]; reduced glutathione [GSH]; and superoxide dismutase [SOD]) responses in mouse liver was also investigated. Different concentrations (2.5%, 5%, 10%, and 15%) of the leachate were administered intraperitoneally for 5 consecutive days to male Swiss albino mice (4 mice/group). A significant (p < 0.05) increase in DNA damage in organs and tissues of treated mice compared to the negative control was observed as evident from the Comet assay parameters: olive tail moment (OTM, arbitrary units) and tail DNA (%). Bone marrow showed maximum DNA damage followed by liver > spleen > kidney > blood as evident by the OTM. A significant increase (p < 0.05) in the level of antioxidant enzymes (CAT and SOD) and LPO with a concurrent decrease in GSH in the liver of treated mice was also observed. Our finding demonstrates that the MSL induces DNA damage in the somatic tissues and organs of mouse as well as induces oxidative stress in the liver. These tissues and organs may be the potential targets in animal and human populations exposed to MSL. This is of relevance to public health; as such exposure could lead to adverse health effects via systemic genotoxicity.

Cypermethrin-induced DNA damage in organs and tissues of the mouse: Evidence from the comet assay

Cypermethrin is the most widely used Type II pyrethroid pesticide because of its high effectiveness against target species and its low mammalian toxicity reported so far. It is a fast-acting neurotoxin and is known to cause free radical-mediated tissue damage. The present study investigates the genotoxic effects of cypermethrin in multiple organs (brain, kidney, liver, spleen) and tissues (bone marrow, lymphocytes) of the mouse, using the alkaline comet assay. Male Swiss albino mice were given 12.5, 25, 50, 100, 200 mg/kg BW of cypermethrin intraperitoneally, daily for 5 consecutive days. A statistically significant ( p < 0.05) dose-dependent increase in DNA damage was observed in all the organs assessed, as evident from the comet-assay parameters, viz., Olive tail moment (OTM; arbitrary unit), tail DNA (%) and tail length (μm). Brain showed maximum DNA damage followed by spleen > kidney > bone marrow > liver > lymphocytes, as evident by the OTM. Our data demonstrate that cypermethrin induces systemic genotoxicity in mammals as it causes DNA damage in vital organs like brain, liver, kidney, apart from that in the hematopoietic system.

Age-dependent increase of etheno-DNA-adducts in liver and brain of ROS overproducing OXYS rats

Reactive oxygen species (ROS) and lipid peroxidation (LPO) play a role in aging and degenerative diseases. To correlate oxidative stress and LPO-derived DNA damage, we determined etheno-DNA-adducts in liver and brain from ROS overproducing OXYS rats in comparison with age-matched Wistar rats. Liver DNA samples from 3- and 15-month-old OXYS and Wistar rats were analyzed for 1, N 6-ethenodeoxyadenosine (εdA) and 3, N 4-ethenodeoxycytidine (εdC) by immunoaffinity/ 32P-postlabelling. While εdA and εdC levels were not different in young rats, adduct levels were significantly higher in old OXYS rats when compared to old Wistar or young OXYS rats. Frozen rat brain sections were analyzed for εdA by immunostaining of nuclei. Brains from old OXYS rats accumulated εdA more frequently than age-matched Wistar rats. Our results demonstrate increased LPO-induced DNA damage in organs of OXYS rats which correlates with their known shorter life-span and elevated frequency of chronic degenerative diseases.

Experimental study of oxidative DNA damage

Animal experiments allow the study of oxidative DNA damage in target organs and the elucidation of dose-response relationships of carcinogenic and other harmful chemicals and conditions as well as the study of interactions of several factors. So far the effects of more than 50 different chemical compounds have been studied in animal experiments mainly in rats and mice, and generally with measurement of 8-oxodG with HPLC-EC. A large number of well-known carcinogens induce 8-oxodG formation in liver and/or kidneys. Moreover several animal studies have shown a close relationship between induction of dative DNA damage and tumour formation.In principle the level of oxidative DNA damage in an organ or cell may be studied by measurement of modified bases in extracted DNA by immunohistochemical visualisation, and from assays of strand breakage before and after treatment with repair enzymes. However, this level is a balance between the rates of damage and repair. Until the repair rates and capacity can be adequately assessed the rate of damage can only be estimated from the urinary excretion of repair products albeit only as an average of the entire body.A number of model compounds have been used to induce oxidative DNA damage in experimental animals. The hepatocarcinogen 2-nitropropane induces up to 10-fold increases in 8-oxodG levels in rat liver DNA. The level of 8-oxodG is also increased in kidneys and bone marrow but not in the testis. By means of 2-nitropropane we have shown correspondence between the increases in 8-oxodG in target organs and the urinary excretion of 8-oxodG and between 8-oxodG formation and the comet assay in bone marrow as well potent preventive effects of extracts of Brussels sprouts. Others have shown similar effects of green tea extracts and its components. Drawbacks of the use of 2-nitropropane as a model for oxidative DNA damage relate particularly to formation of 8-aminoguanine derivatives that may interfere with HPLC-EC assays and have unknown consequences. Other model compounds for induction of oxidative DNA damage, such as ferric nitriloacetate, iron dextran, potassium bromate and paraquat, are less potent and/or more organ specific.Inflammation and activation of an inflammatory response by phorbol esters or E. coli lipopolysaccharide (LPS) induce oxidative DNA damage in many target cells and enhance benzene-induced DNA damage in mouse bone marrow.Experimental studies provide powerful tools to investigate agents inducing and preventing oxidative damage to DNA and its role in carcinogenesis. So far, most animal experiments have concerned 8-oxodG and determination of additional damaged bases should be employed. An ideal animal model for prevention of oxidative DNA damage has yet to he developed.

Sex hormone-induced nuclear DNA damage and lipid peroxidation in the dorsolaterel prostates of Noble rats

To date, few studies have been reported on any aspect of DNA damage in organs of intact animals. We and others demonstrated induction of high incidences of dysplasia, a precancerous proliferative lesion, and adenocarcinoma selectively in the dorsolateral prostates (DLPs) of Noble rats exposed to a long-term combined testosterone and estradiol-17β treatment (T + E 2-treatment). We here report induction of a significant increase in DNA strand breakage and accumulation of lipid peroxidation fluorescent products in the DLPs, but not in the ventral prostates (VPs), of rats treated with T + E 2 for 16 weeks. These results indicate that this dual hormone treatment has free radical-based DNA damaging effect on rat DLP and therefore may have tumor-initiating action. Since a similar effect was not observed in regenerating DLPs of castrated rats following testosterone replacement, we conclude that the genotoxic effect of the dual hormone treatment is a direct result of hormone action and not secondarily due to enhancement of cell proliferation.