Genotoxic evaluation of pirfenidone using erythrocyte rodent micronucleus assay

Effect of High-Dose Topical Minoxidil on Erythrocyte Quality in SKH1 Hairless Mice

Simple Summary

In any animal species, involuntary exposure to unknown agents may increase genetic material damage. This genetic damage can also induce the appearance of diseases such as cancer or other pathologies, including problems that can be passed on to the offspring of the damaged individual. For instance, living organisms may be affected due to the use of medications or exposure to certain chemical, physical, or biological agents which cause cell failure. This impaired function acts as an indicator that helps identify and evaluate damage in order to avoid or minimize it. In this work, excessive doses of a cosmetic drug for topical use in dermatological treatments, known as minoxidil, produced defects in the blood of hairless mice, particularly in red cells, indicating loss of DNA, a situation that may compromise life or the offspring by causing damage to their genetic material. It is important to consider that compounds may be tissue- or species-specific, although we cannot rule out the possibility that similar damage could occur in other animal species. Thus, excessive exposure to this compound should be prevented.

Abstract

SKH1 hairless mice are widely used in carcinogenesis and dermatology research due to their bare skin, as exposure to different agents is facilitated. Minoxidil is a cosmetic drug that is recognized as a mitogenic agent, and mitogens are suggested to have carcinogenic and mutagenic potential by inducing cell division and increasing the possibility of perpetuating DNA damage. Therefore, we hypothesized that the application of high doses of minoxidil to the skin of hairless mice would increase the number of micronucleated erythrocytes (MNEs) in peripheral blood. The objective of this study was to evaluate the topical administration of high doses of minoxidil on peripheral blood erythrocytes of SKH1 mice by means of micronucleus assay. Minoxidil was administered on the entire body surface of mice every 12 or 24 h. Minoxidil dosing every 24 h increased the number of micronucleated polychromatic erythrocytes (MNPCEs), and dosing every 12 h increased the number of MNEs and MNPCEs, as compared to baseline and the negative control group. No decrease in polychromatic erythrocyte frequencies was observed in the minoxidil groups. Therefore, topical application of high minoxidil doses to mice can produce DNA damage, as observed through an increase in the number of MNEs, without producing cytotoxicity, possibly due to its mitogenic effect.

Genome Damage in Rats after Transplacental Exposure to Jatropha dioica Root Extract

Jatropha dioica is traditionally used owing to its antiviral, antifungal, and antimicrobial properties. But, toxicological information regarding J. dioica root total extract is currently limited. The aim of this work was to evaluate in a rat model, the transplacental genotoxicity effect of J. dioica aqueous root total extract. Three different J. dioica aqueous root total extract doses (60, 100, and 300 mg/kg) were administered orally to Wistar rats during 5 days through the pregnancy term (16-21 days). Pregnant rats were sampled every 24 h during the last 6 days of gestation, and pubs were sampled at birth. Genome damage in dams and their newborn pups transplacentally exposed to J. dioica was evaluated by in vivo micronuclei assay. We evaluated the frequency of micronucleated erythrocytes (MNE), micronucleated polychromatic erythrocytes (MNPCE), and polychromatic erythrocytes (PCE) in peripheral blood samples from pups and MNPCE and PCE in pregnant rats. No genotoxic effect was observed after oral administration of the three different doses of aqueous root total extract of J. dioica in pregnant or in their newborn pubs, after transplacental exposure. A significant decrease in PCE frequency was noted in samples from pubs of rats treated with the highest dose of J. dioica extract. The aqueous total root extract of J. dioica at the highest dose tested in our research do have cytotoxic effect in pups transplacentally exposed to this plant extract. Moreover, neither a genotoxic nor a cytotoxic effect was observed in pregnant rats. In the present work, there was no evidence of genome damage in the rat model after transplacental exposure to J. dioica aqueous root total extract.

Effect of Moringa oleifera consumption on diabetic rats

BACKGROUND

Therapeutic use of leaves of M. oleifera has been evaluated in diabetes because of its possible capacity to decrease blood glucose and lipids concentration after ingestion, as result of the polyphenols content and others compounds. Nevertheless most results have been obtain from leaf extract, therefore this study would use leaf powder as the regular way of consumption of population to know effects over toxicity glucose, triglycerides, cholesterol, corporal weight, and predominant groups of microbiota.

METHODS

Powdered leaf was administrated in different doses to know toxicity and genotoxicity using LD50 and micronuclei assay. Hyperglycemia was induced by alloxan on Sprague Dawley rats. Glucose and body weight were measured once a week meanwhile cholesterol and triglycerides were analyzed at the end of the study by commercial kits. Different organs were examined by hematoxylin-eosin technique. Lactic acid bacteria and Enterobacteriaceae were enumerated from stool samples.

RESULTS

The tested doses revealed no lethal dose and no significant differences in genotoxicity parameter. The consumption of the leaves showed a hypoglycemic effect (< 250 mg/dL in diabetic M. oleifera treated group), however in corporal weight showed an increased (> 30 g over no M. oleifera treated groups). There was no change in enumeration of lactic acid bacteria (8.4 CFU/g) but there were differences in the predominance of type of lactobacillus and enterobacteria enumeration.

CONCLUSIONS

These results help to increase information over the most popular use of M. oleifera and its safety. However there are needed more studies over the hypoglycemic mechanisms and effects over intestinal microbiota.

Micronucleated Erythrocytes in Peripheral Blood from Neonate Rats Exposed by Breastfeeding to Cyclophosphamide, Colchicine, or Cytosine-Arabinoside

Genotoxic exposure to chemical substances is common, and nursing mothers could transmit harmful substances or their metabolites to their offspring through breast milk. We explored the possibility of determining genotoxic effects in the erythrocytes of breastfeeding rat pups whose mothers received a genotoxic compound while nursing. Ten groups of female rats and five pups per dam were studied. The control group received sterile water, and the experimental groups received one of three different doses of cyclophosphamide, colchicine, or cytosine-arabinoside. Blood smears were prepared from samples taken from each dam and pup every 24 h for six days. There were increased numbers of micronucleated erythrocytes (MNEs) and micronucleated polychromatic erythrocytes (MNPCEs) in the samples from pups in the experimental groups (P < 0.02) and increased MNPCE frequencies in the samples from the dams (P < 0.05). These results demonstrate the vertical transmission of the genotoxic effect of the compounds tested. In conclusion, assessing MNEs in breastfeeding neonate rats to assess DNA damage may be a useful approach for identifying genotoxic compounds and/or cytotoxic effects. This strategy could help in screening for therapeutic approaches that are genotoxic during the lactation stage and these assessments might also be helpful for developing preventive strategies to counteract harmful effects.

Genotoxicity of nimesulide in Wistar rats

It is mandatory for all new drugs to be tested for their potential genotoxicity in addition to general toxicity testing. Some old drugs have not been tested adequately for their genotoxic effects because these were in use before the local regulations were enforced. According to the material safety database, the toxicological effect of nimesulide is not yet fully understood. The present study therefore aimed to explore the genotoxic potential of nimesulide in Wistar albino rats. Nimesulide at the dose level of 50 (Gr-50), 100 (Gr-100) and 200 (Gr-200) mg/kg body weight (b.w.) was given orally. Each rat in treated groups (Gr-50 to Gr-200; n = 10) and negative control group (Gr-NC; n = 10) were administered orally (p.o.) with nimesulide and normal saline, respectively, for 14 days. Similarly, rats of positive control (Gr-PC; n = 10) were administered with cyclophosphamide (CPA; 20 mg/kg b.w.) intraperitoneally. CPA served as positive control, whereas normal saline served as as negative control. Approximately 1-2 mL of blood was collected from retro-orbital sinus for comet assay and subsequently rats were sacrificed to aspirate the femoral bone marrow for the micronucleus test. Structural chromosomal aberration, micronucleated polychromatic erythrocytes (MnPCEs), polychromatic erythrocytes (PCEs) and comet tail length were calculated using micronucleus assay and comet assay, respectively, which served as markers of genotoxicity. In the present study, it was observed that a significant increase in (1) different classified structural chromosomal aberrations with increase in nimesulide dose, such as gaps (50 mg/kg), gaps, breaks and pulverizations (100 mg/kg) and gaps, breaks, fragments, rings and pulverizations (200 mg/kg) and (2) % MnPCE and comet tail length was observed in animals treated with CPA (p < 0.001) or 200 mg of nimesulide (p < 0.05), as compared to negative control. In conclusion, nimesulide (200 mg/kg b.w.) produced a potential genotoxicity in rats.