Evaluation of chromosome aberrations, sister chromatid exchange and micronuclei in cultured cord-blood lymphocytes of newborns of women treated for epilepsy during pregnancy

Reduction of Genotoxicity of Carbamazepine to Human Lymphocytes by Pre-treatment with Vitamin B12

BACKGROUND

Carbamazepine (CBZ) is widely used as an anti-epileptic drug. Vitamin B12 has been shown to protect against DNA damage caused by several mutagenic agents.

OBJECTIVE

This study aimed to investigate the effect of vitamin B12 on CBZ-induced genotoxicity in cultured human lymphocytes.

METHODS

Sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) genotoxic assays were utilized to achieve the study objective.

RESULTS

The results showed significantly higher frequencies of CAs and SCEs in the CBZ-treated cultures (12 μg/mL) compared to the control group (P<0.01). The genotoxic effects of CBZ were reduced by pre-treatment of cultures with vitamin B12 (13.5μg/ml, P<0.05). Neither CBZ nor vitamin B-12 showed any effects on mitotic and proliferative indices.

CONCLUSION

CBZ is genotoxic to lymphocyte cells, and this genotoxicity can be reduced by vitamin B12.

Carbamazepine at environmentally relevant concentrations caused DNA damage and apoptosis in the liver of Chinese rare minnows (Gobiocypris rarus) by the Ras/Raf/ERK/p53 signaling pathway

To assess genetoxicity and the underlying mechanisms of carbamazepine (CBZ) toxicity in fish, adult Chinese rare minnows (Gobiocypris rarus) were exposed to 1, 10, and 100 μg/L CBZ for 28 d. Comet assays indicated that hepatic DNA damage was significantly increased in groups of minnows exposed to CBZ at all concentrations in a dose-dependent manner compared to those of the control groups (p < 0.05). Liver levels of 8-hydroxydeoxyguanosine (8-OHdG) were significantly increased at 10 and 100 μg/L CBZ (p < 0.05). TUNEL assays indicated that the average apoptotic rates of the livers of female and male minnows were significantly increased following exposure to CBZ at all concentrations for 28 d (p < 0.05). Significant increases in caspase 3 and 9 activities after CBZ exposure at all concentrations and caspase 8 at 10 and 100 μg/L CBZ exposure reflected the presence of mitochondrial apoptosis (p < 0.05). The mRNA levels of gadd45a, mdm2, casp3 and casp9 in female and male minnows exposed to CBZ at all concentrations were significantly increased compared with those in the control groups (p < 0.05). Significant increases in the levels of p21 in female minnows exposed to 1 and 100 μg/L CBZ, p53 in female minnows at all CBZ treatments and bcl2 in male minnows exposed to 1 and 100 μg/L CBZ were observed, indicating p53 pathway activation. The inhibition of ras levels in females and males exposed to CBZ at all concentrations and increased levels of raf1 in males exposed to CBZ at all concentrations indicated Ras/Raf1/MAPK (ERK) activation. Therefore, the present study demonstrates that CBZ at environmentally relevant levels induces DNA damage and apoptosis in Chinese rare minnows by the Ras/Raf/ERK/p53 signaling pathway.

Insight into the generation of toxic products during chloramination of carbamazepine: Kinetics, transformation pathway and toxicity

As a widely used antiepileptic drug, carbamazepine (CBZ) has been frequently detected in aquatic environments, even in drinking water. Chloramine is a widely used alternative disinfectant due to its low-level formation of regulated disinfection byproducts (DBPs). However, there is previous evidence linking product mixtures of chloraminated CBZ to stronger DNA damage effects than those caused by CBZ itself. The present study further investigated the reaction rate, transformation mechanism and multi-endpoint toxicity of transformation products (TPs) of CBZ treated with NH₂Cl under different pH conditions. The results showed that the reaction between CBZ and NH₂Cl at pH 8.5, where NH₂Cl is stable, is a second-order reaction with a rate of 4.2 M^-1 h^-1. Compared to both alkaline and acidic conditions, CBZ was quickly degraded at pH 7. This indicated that HOCl produced from NH₂Cl hydrolysis is more effective in degrading CBZ than NH₂Cl and NHCl₂. Furthermore, the concentration variation of four TPs formed during the chloramination of CBZ under different pH conditions was investigate by quantitative analysis, and the transformation pathway from CBZ to 9(10H)-acridone was confirmed. Three of the detected TPs showed cytotoxicity, DNA damage effects or chromosome damage effects. Acridine and 9(10H)-acridone, which accumulated with increasing time, showed higher cytotoxic or genotoxic effects than CBZ itself. In addition, a similar transformation mechanism was observed in real ambient water during simulated chloramination with a low level of CBZ. These results suggested that despite the chloramination of CBZ being slower than chlorination, TPs with higher cytotoxicity or genotoxicity may lead to greater toxic risks.

Chlorination, chloramination and ozonation of carbamazepine enhance cytotoxicity and genotoxicity: Multi-endpoint evaluation and identification of its genotoxic transformation products

Investigations have focused on the removal and transformation of pharmaceuticals during drinking water and wastewater treatment. In the present study, we investigated for the first time the changes of the cytotoxicity and genotoxicity based on different modes of action (MoAs) during chlorination, chloramination and ozonation processes of the anti-epileptic drug carbamazepine (CBZ). The results illustrated that ozonation enhanced the cytotoxicity and the chromosome damage effects on CHO-K1 cells detected by cytokinesis-block micronucleus (CBMN) assay based on high-content screening technique, though ozonation showed the highest removal efficiency for CBZ. Non-target chemical analysis followed by quantitative structure-activity relationship (QSAR) analysis for the transformation products (TPs) suggested that the chromosomal damage effects could probably be attributed to 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM) and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD). In contrast to CBZ itself and the ozonated sample, the chlorinated and chloraminated samples caused DNA damage effects in SOS/umu test. Acridine, 9 (10) H-acridone, chlorinated 9 (10) H-acridone and TP-237, which were first identified in the chlorination or chloramination processes, were predicted to be the DNA damaging agents. These genotoxic TPs were primarily generated from the oxidation of seven-membered N-heterocyclic in CBZ. This study highlighted the potential adverse effects generated in ozonation process and the oxidation of N-heterocyclic containing pollutants.

Evaluation of apoptotic cell death on liver and kidney tissues following administration of levetiracetam during prenatal period

OBJECTIVE

Levetiracetam is a new generation antiepileptic drug used in treatment of patients with epilepsy and has adverse effects on different tissues. We aimed to evaluate the apoptotic effects of levetiracetam exposure during pregnancy on liver and kidney tissues of rat pups.

METHODS

We analyzed the newborn rat pups exposed to levetiracetam during prenatal period. Fifteen pregnant female rats were divided into three groups. The group 1 and 2 rats were treated with different doses of levetiracetam (25 mg/kg/d and 50 mg/kg/d, respectively) from gestational days 1-22 during pregnancy. Group 3 (control group) was treated with the same volume of saline. Apoptosis was evaluated by the terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) method. Liver and kidney tissues from rat pups were used for investigation.

RESULTS

The percent of TUNEL positive apoptotic cells in group 1 were 22 and 17.5 for kidney and liver, respectively. The percent of TUNEL positive apoptotic cells in group 2 were 20.9 and 20.9 for kidney and liver, respectively. The percent of TUNEL positive apoptotic cells in group 3 were 18.4 and 17.1, respectively, for kidney and liver. The apoptotic index was the same in kidney and liver tissues of all groups.

CONCLUSION

Our results demonstrate that the prenatal exposure of levetiracetam has no apoptotic effects on liver and kidney of rat pups and, it has biosafety in pregnancy in terms of apoptosis. The first study evaluating the apoptotic effects on liver and kidney tissues following administration of levetiracetam during prenatal period.

Effect of saffron (Crocus sativus L.) on sodium valporate induced cytogenetic and testicular alterations in albino rats

The present study investigated the cytogenetic and testicular damage induced by the antiepileptic drug, sodium valporate (SVP) in albino rats and the effect of saffron aqueous extracts. Treating rats with SVP caused a significant increase in the chromosomal aberrations either structural or numerical and decreased the mitotic index. Besides, animals administered SVP showed DNA damage appeared in the single strand breaks (comet assay). Testis of SVP-treated rats showed many histopathological changes. A significant decrease in seminiferous tubules and their epithelial heights diameters and inhibition of spermatogenesis was recorded. In addition, the number of sperm head abnormalities was increased. Biochemical results revealed an increase in malondialdhyde (MDA) which is lipid peroxidation marker and a significant decrease in the level of serum antioxidant enzyme, catalase (CAT) and reducing antioxidant power (RAP). Animals given SVP and saffron showed an improvement in chromosomal aberrations, mitotic index, DNA damage and testicular alterations caused by SVP. Moreover, MDA decreased and CAT and RAP increased. It is concluded from the present results that the ameliorative effects of saffron extract against SVP-induced cytogenetic and testicular damage in albino rats may be due to the presence of one or more antioxidant components of saffron.

Evidence that BRCA1- or BRCA2-associated cancers are not inevitable

Inheriting a BRCA1 or BRCA2 gene mutation can cause a deficiency in repairing complex DNA damage. This step leads to genomic instability and probably contributes to an inherited predisposition to breast and ovarian cancer. Complex DNA damage has been viewed as an integral part of DNA replication before cell division. It causes temporary replication blocks, replication fork collapse, chromosome breaks and sister chromatid exchanges (SCEs). Chemical modification of DNA may also occur spontaneously as a byproduct of normal processes. Pathways containing BRCA1 and BRCA2 gene products are essential to repair spontaneous complex DNA damage or to carry out SCEs if repair is not possible. This scenario creates a theoretical limit that effectively means there are spontaneous BRCA1/2-associated cancers that cannot be prevented or delayed. However, much evidence for high rates of spontaneous DNA mutation is based on measuring SCEs by using bromodeoxyuridine (BrdU). Here we find that the routine use of BrdU has probably led to overestimating spontaneous DNA damage and SCEs because BrdU is itself a mutagen. Evidence based on spontaneous chromosome abnormalities and epidemiologic data indicates strong effects from exogenous mutagens and does not support the inevitability of cancer in all BRCA1/2 mutation carriers. We therefore remove a theoretical argument that has limited efforts to develop chemoprevention strategies to delay or prevent cancers in BRCA1/2 mutation carriers.