Role of oxidative stress in antituberculous drugs (individuals and combined) cytotoxicity in HepG2 cells

Hepatotoxicity is a common side and toxic effect of Antituberculous (Anti-TB) drugs with reported higher incidence with anti-TB combinations. Oxidative stress was shown to have a role. This study examined oxidative stress effects of the first line Anti-TB drugs; Rifampicin (RIF), isoniazid (INH) and pyrazinamide PZA (individually and combined) on HepG2 cells. MTT assay (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) was used to study the cytotoxic effect of the tested Anti-TB drugs. The effect of anti-TB drugs on total glutathione HepG2 cells and the production of reactive oxygen species (ROSs) were studied (individually and in combinations). Furthermore, the protective effect of the antioxidant reduced glutathione was assayed. The data revealed that the tested anti-TB were cytotoxic to HepG2 cells. RIF was the most potent. The tested drugs in their estimated IC50s, to different extents, enhanced significantly (P<0.0001) ROSs production and decreased total glutathione (P <0.0001). Furthermore, 48 hours pre-treatment with INH (3mM) significantly increased ROS production and decreased glutathione with RIF (0.1mM) (P <0.01 and P <0.05 respectively) and PZA (10 mM) (P <0.01 and P <0.05 respectively). Combined RIF (0.1mM) and INH (3mM) significantly decreased total glutathione (P<0.05 for each) and increased ROSs production (P<0.05) in HepG2 cells (P<0.05 for each). Interestingly, reduced glutathione (GSH) significantly decreased the cytotoxicity of RIF and INH (P=0.005 and 0.015, respectively). These data showed that oxidative stress play a crucial role in anti-TB induced hepatotoxicity, which can be alleviated by inclusion of antioxidant in therapy, though there is need of clinical trials. Moreover, combined anti-TB therapy should be considered as a risk factor with any other oxidative liver injuries

Drug resistance mechanisms in a high grade glioma cell line

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumour. Despite advances in GBM treatment, there is a high frequency of local relapse due to the acquisition of drug resistance. Investigation of glioma cell lines will help us to understand the molecular basis of this hard to treat tumour. In this study, the rat C6 glioma cell line was used as a model alongside two drug selected derivatives (C6-etoposide and C6-irinotecan) to investigate the mechanisms of chemo-resistance in glioma by identifying candidate proteins, genes, and key signalling pathways. Proteomic (2D gel electrophoresis) and genomic (gene array) analyses were performed to determine protein and gene expression changes. Integration of this data with cellular pathway analysis resulted in the prediction that cellular migration and the response to oxidative stress would be distinct in the drug selected C6 cell lines. Cell migration was subsequently assessed using wound scratch repair and transwell migration assays, whilst the response to oxidative stress produced by reactive oxygen species was determined fluorimetrically. The C6 cell line exposed to irinotecan (DNA topoisomerase I inhibitor) showed reduced migration, even under the influence of chemoattractant, compared to other cell lines, consistent with alterations in the expression of collagen genes. The C6 cell line exposed to etoposide (DNA topoisomerase II inhibitor) showed greater resistance to oxidative stress which was proposed to be due to alterations in the signalling pathways downstream of the PTEN/PI3Kinase. Future studies, investigating the effect of PI3Kinase pathway inhibitors are considered and it is proposed that further research into this signalling pathway will be able to uncover the molecular basis of distinct chemo-resistance in this important model cell system for aggressive glioma

The role of oxidative stress in antipsychotics induced ovarian toxicity

This study tested the hypothesis that oxidative stress could be an underlying mechanism for APs-induced ovarian cytotoxicity and reproductive dysfunction. Rat ovarian theca interstitial cells (TICs) were isolated and treated with four APs [chlorpromazine (CPZ), haloperidol (HAL), risperidone (RIS) and clozapine (CLZ)]. MTT assay was used to test the effects of these antipsychotics on TICs viability and to estimate their 50% inhibitory concentrations (IC50s). The effects of APs (IC50s and 1 μM concentrations) on the activities of caspases-3, -8 and -9, reactive oxygen species (ROS) production, total intracellular glutathione and lipid peroxidation (LPO) in TICs were assessed. The effect of antioxidants (reduced glutathione (GSH) and quercetin) on the APs-induced cytotoxicity on TICs was investigated. MTT assay showed all APs to reduce TICs viability. CPZ, HAL and CLZ significantly increased the activity of caspases-3, -8 and -9 (P < 0.0001, < 0.0001 and < 0.01, respectively). All APs at IC50s significantly (P < 0.0001) increased ROS production, decreased total intracellular glutathione and increased LPO. MTT assay in the presence of antioxidants (reduced GSH (5 mM) or quercetin (50 mM)) showed each antioxidant to significantly inhibit the effects of APs at their IC50s on TICs viability. In conclusion, oxidative stress seems to be a possible mechanism for APs-induced ovarian and reproductive toxicity

Antidepressants are cytotoxic to rat primary blood brain barrier endothelial cells at high therapeutic concentrations

Antidepressants are commonly employed for the treatment of major depressive disorders and other psychiatric conditions. We investigated the relatively acute cytotoxic effects of three commonly prescribed antidepressants: fluoxetine, sertraline, and clomipramine on rat primary blood brain barrier endothelial cells over a concentration range of 0.1–100 μM. At therapeutic concentrations (0.1 μM) no significant cytotoxicity was observed after 4, 24, or 48 h. At high therapeutic to overdose concentrations (1–100 μM), antidepressants reduced cell viability in proportion to their concentration and exposure duration. At 1 μM, antidepressants significantly reduced mitochondrial membrane potential. At drug concentrations producing ~ 50% inhibition of cell viability, all drugs significantly reduced cellular oxygen consumption rates, activities of mitochondrial complexes I and III, and triggered a significant increase of lactate production. Fluoxetine (6.5 μM) and clomipramine (5.5 μM) also significantly lowered transcellular transport of albumin. The mechanism of cellular cytotoxicity was evaluated and at high concentrations all drugs significantly increased the production of reactive oxygen species, and significantly increased the activity of the pro-apoptotic caspases-3, 8, and 9. Comet assays revealed that all drugs were genotoxic. Pre-incubation of cells with glutathione significantly ameliorated antidepressant-induced cytotoxicity, indicating the potential benefit of treatment of overdosed patients with antioxidants

Therapeutic concentrations of antidepressants inhibit pancreatic beta-cell function via mitochondrial complex inhibition

Diabetes mellitus risk is increased by prolonged usage of antidepressants (ADs). Although various mechanisms are suggested for their diabetogenic potential, whether a direct effect of ADs on pancreatic β-cells is involved is unclear. We examined this idea for 3 ADs: paroxetine, clomipramine and, with particular emphasis, fluoxetine, on insulin secretion, mitochondrial function, cellular bioenergetics, KATP channel activity, and caspase activity in murine and human cell-line models of pancreatic β-cells. Metabolic assays showed that these ADs decreased the redox, oxidative respiration, and energetic potential of β-cells in a time and concentration dependent manner, even at a concentration of 100 nM, well within the therapeutic window. These effects were related to inhibition of mitochondrial complex I and III. Consistent with impaired mitochondrial function, lactate output was increased and insulin secretion decreased. Neither fluoxetine, antimycin nor rotenone could reactivate KATP channel activity blocked by glucose unlike the mitochondrial uncoupler, FCCP. Chronic, but not acute, AD increased oxidative stress and activated caspases, 3, 8, and 9. A close agreement was found for the rates of oxidative respiration, lactate output and modulation of KATP channel activity in MIN6 cells with those of primary murine cells; data that supports MIN6 as a valid model to study beta-cell bioenergetics. To conclude, paroxetine, clomipramine and fluoxetine were all cytotoxic at therapeutic concentrations on pancreatic beta-cells; an action suggested to arise by inhibition of mitochondrial bioenergetics, oxidative stress and induction of apoptosis. These actions help explain the diabetogenic potential of these ADs in humans

Effect of antipsychotics on mitochondrial bioenergetics of rat ovarian theca cells

Background Antipsychotics (APs) are widely prescribed drugs, which are well known to cause reproductive adverse effects through mechanisms yet to be determined. The purpose of this study was to investigate the effect of antipsychotics on mitochondrial bioenergetics of rat ovarian theca cells as a possible mechanism of reproductive toxicity. Methods Isolated rat theca interstitial cells (TICs) were treated with two typical (chlorpromazine [CPZ] and haloperidol [HAL]) and two atypical APs (risperidone [RIS] and clozapine [CLZ]). The effects of these APs on TICs bioenergetics (ATP content, mitochondrial complexes I and III activities, oxygen consumption rates (OCRs), mitochondrial membrane potential (MPP) and lactate production) and on steroidogenesis (androstenedione and progesterone synthesis) were investigated. Results All APs resulted in a concentration-dependent decrease in the ATP content of TICs. All APs at their estimated IC50s (6 μM, 21 μM, 35 μM and 37 μM for CPZ, HAL, CLZ and RIS respectively) significantly decreased TICs OCRs (p < 0.0001), MPP (p < 0.0001) and significantly (p = 0.0003) inhibited mitochondrial complex I activity. Only typical APs inhibited complex III (p = 0.005). Also, APs at IC50s increased TICs lactate production to varying degrees. All APs used at their IC50s significantly inhibited progesterone (p = 0.0022) and androstenedione (p = 0.0027) production. Only CPZ was found to inhibit these hormones at the low concentration (1 μM). Conclusion All four antipsychotics seem to inhibit mitochondrial bioenergetics and steroidogenesis in rat’s ovarian theca cells. These findings support the hypothesis that APs-induced reproductive toxicity may be through mechanisms involving mitochondrial insult>. Further research is required to establish the link between APs-induced mitochondrial dysfunction and disordered steroidogenesis

Contribution of ABCG2 gene polymorphisms (G34A and C376T) in the prognosis of colorectal cancer

73-78This study aims to assess the association of two single nucleotide polymorphisms (SNPs), G34A and C376T, in the ABCG2 gene with the risk of developing CRC. To the best of our knowledge, this is the first study that determined the role of genetic variations in the ABCG2 gene with the risk of CRC in Saudi Arabia. The gDNA was extracted from the blood of 58 CRC patients and 48 healthy subjects. The DNA sequencing was used to determine the distribution of genotypes. The results showed that CRC patients carried a heterozygous (GA) genotype for SNP G34A had a low risk of developing CRC (odds ratio=0.015, 95% CI [0.00–0.12]; risk ratio=0.35, 95% CI [0.25–0.12], P P 0.0001). In conclusion, the results indicated that a heterozygous (GA) genotype in SNP G34A may decrease the risk of CRC development, whereas, the heterozygous (CT) genotype in SNP C376T may increase the risk of CRC. The results may suggest a protective role of ABCG2 SNP G34A against CRC and a deleterious effect of ABCG2 SNP C376T for increasing the risk of CRC

Long-term exposure to irinotecan reduces cell migration in glioma cells.

In spite of considerable research into the therapies for glioblastoma multiforme this tumour type remains very difficult to treat. As well as having a tendency to be inherently resistant to chemotherapy, glioblastoma multiforme also displays local invasion. Cell line studies have a continued and important role to play in understanding the mechanisms associated with both chemotherapy resistance and invasion. In the current study we have utilized the C6 glioma cell line to investigate the response to long-term, clinically relevant application of topoisomerase I and II inhibitors. Treatment with etoposide resulted in an increase in resistance to this topoisomerase II inhibitor. By contrast, the continuous exposure to a topoisomerase I inhibitor did not result in increased drug resistance, but was associated with a reduction in cell migration. This data supports further investigation of topoisomerase I inhibition as a means to inhibit glioma invasion without the development of parallel chemoresistance

An Investigation of the Neurotoxic Effects of Malathion, Chlorpyrifos, and Paraquat to Different Brain Regions

Acute or chronic exposures to pesticides have been linked to neurotoxicity and the potential development of neurodegenerative diseases (NDDs). This study aimed to consider the neurotoxicity of three widely utilized pesticides: malathion, chlorpyrifos, and paraquat within the hippocampus (HC), corpus striatum (CS), cerebellum (CER), and cerebral cortex (CC). Neurotoxicity was evaluated at relatively low, medium, and high pesticide dosages. All pesticides inhibited acetylcholinesterase (AChE) and neuropathy target esterase (NTE) in each of the brain regions, but esterase inhibition was greatest in the HC and CS. Each of the pesticides also induced greater disruption to cellular bioenergetics within the HC and CS, and this was monitored via inhibition of mitochondrial complex enzymes I and II, reduced ATP levels, and increased lactate production. Similarly, the HC and CS were more vulnerable to redox stress, with greater inhibition of the antioxidant enzymes catalase and superoxide dismutase and increased lipid peroxidation. All pesticides induced the production of nuclear Nrf2 in a dose-dependent manner. Collectively, these results show that pesticides disrupt cellular bioenergetics and that the HC and CS are more susceptible to pesticide effects than the CER and CC

DIJAMETAR I MASA OČNE LEĆE KAO INDIKATOR STAROSTI Leiognathus equulus SAKUPLJENIH IZ MORA OMANA

In the leiognathid fish, Leiognathus equulus the diameter of the eye lens can be used for identifying first-year animals, while the eye lens weight proved unreliable for age determination.Kod vrste, Leiognathus equulus korišten je dijametar očne leće za određivanje jednogodišnjih organizama, dok se masa očne leće nije mogla uzeti kao pouzdana za određivanje starosti