Cartap-induced cytotoxicity in mouse C2C12 myoblast cell line and the roles of calcium ion and oxidative stress on the toxic effects

Amelioration of Hepatotoxic and Neurotoxic Effect of Cartap by Aloe vera in Wistar Rats

Pesticide exposure can pose a serious risk to nontarget animals. Cartap is being broadly used in agricultural fields. The toxic effects of cartap on the levels of hepatotoxicity and neurotoxicity have not been properly studied in mammalian systems. Therefore, the present work focused on the effect of cartap on the liver and brain of Wistar rats and made an assessment of the ameliorating potential of A. vera. The experimental animals were divided into 4 groups, comprising six rats in each: Group 1-Control; Group 2-A. vera; Group 3-Cartap; and Group 4-A. vera + Cartap. The animals orally given cartap and A. vera were sacrificed after 24 h of the final treatment and histological and biochemical investigations were conducted in liver and brain of Wistar rats. Cartap at sublethal concentrations caused substantial decreases in CAT, SOD, and GST levels in the experimental rats. The activity levels of transaminases and phosphatases in cartap group were also found to be substantially altered. The AChE activity was recorded as decreasing in RBC membrane and brain of the cartap-treated animals. The TNF-α and IL-6 level in serum were increased expressively in the cartap challenged groups. Histological investigation of liver showed disorganized hepatic cords and severely congested central veins due to cartap. However, the A. vera extract was observed to significantly protect against the effects of cartap toxicity. The protective impact of A. vera against cartap toxicity may be due to the existence of antioxidants in it. These findings suggest that A. vera may be developed as a potential supplement to the appropriate medication in the treatment of cartap toxicity.

Ameliorative Impact of Aloe vera on Cartap Mediated Toxicity in the Brain of Wistar Rats

Exposure to pesticides can pose a greater threat to multiple organs of nontarget animals. Cartap is a thiocarbamate pesticide, broadly used in agricultural fields. The assessment of neurotoxicity of cartap has not been properly studied in the mammalian systems. The present investigation unveils the toxic effects of cartap in the brain of Wistar rats its amelioration by using aqueous extract of Aloe vera leaves. We have used 4 groups of animals comprising six in each: Group 1- control, Group 2- control with Aloe vera, Group 3- cartap, Group 4- cartap with Aloe vera treated. After 15 days of treatment, biochemical investigations were conducted. Wistar rats orally exposed to sublethal doses of cartap, showed significant variations in the levels of prooxidants i.e. MDA and GSH (an oxidative stress marker) and enzymatic antioxidants i.e. SOD, CAT, GST, GPx. The decreased levels of CAT, SOD, GST and increased levels of GPx were detected in the experimental rats treated with cartap. The significant alterations were recorded with the declined activities of LDH and AChE, considered as the biomarker of energy metabolism and altered cholinergic function, respectively. However, the pre-administration of aqueous extract of Aloe vera leaves was found to markedly ameliorate the toxic effects of cartap by shielding the levels of aforesaid oxidative markers near to the control. The ameliorative impact of Aloe vera, might be due to the presence of several antioxidant molecules in it which were able to counter the oxidative stress generated by cartap stress. These results suggested that Aloe vera could be utilized as a possible supplement with the relevant therapeutics in the suitable management of cartap toxicity in association.

A new method for cartap detection with high sensitivity and selectivity based on the inner filter effect between GSH-Cu NCs and Au NPs

Herein, a novel and sensitive fluorescence method for cartap determination is established on the basis of the inner filter effect (IFE) of gold nanoparticles (Au NPs) on the fluorescence of glutathione protected Cu NCs (GSH-Cu NCs). In the presence of Au NPs, the fluorescence of GSH-Cu NCs was strongly quenched by the IFE because the absorption spectra of Au NPs overlap well with the emission spectra of GSH-Cu NCs. Upon addition of cartap, cartap could induce the aggregation of Au NPs whose absorption spectrum does not overlap with the emission spectrum of GSH-Cu NCs. Then, with the increase in cartap concentration, the IFE-decreased fluorescence was gradually recovered, realizing the fluorescence sensing of cartap. Under optimal conditions, the proposed method has a good linear relationship with cartap concentration in the range of 7-100 nM, and the detection limit is 3.34 nM. In addition, satisfactory results were obtained for cartap analysis using tap water and cabbage as real samples, which demonstrated that the method as-developed would have great practical application prospects.

Biophysical study on the interaction of cartap hydrochloride and hemoglobin: Heme degradation and functional changes of protein

Cartap hydrochloride is a mildly perilous insecticide known as "Padan" which is used largely in agricultural farms to control weevil and caterpillars. The over use of cartap causes harmful effects on human health. Since the blood may acts as a target and carrier for insecticides, the effect of these compounds on blood in mammalian toxicology is very important. Hemoglobin is a tetramer protein that play critical role in oxygen transport. The aim of this study was to analyze and compare the function and structural changes of hemoglobin in the presence of different concentrations of cartap by employing different spectroscopic techniques. The obtained results show that cartap has a high hemolytic effect which is increased with cartap concentration and reduces the thermal midpoint of hemoglobin. Fluorescence measurements reveal heme degradation at different concentrations of cartap. In consequence of theoretical and experimental results, cartap has an undesirable effect on hemoglobin structure and function.

Studies on oral subacute toxicity of cartap in male mice

S-[3-carbamoylsulfanyl-2-(dimethylamino)propyl] carbamothioate (Cartap) (CAS number: 15263-52-2) is a synthetic insecticide of thiocarbamates group that is extensively used in field of agriculture for controlling of several pests like rice stem borer, leaf folder pests in paddy field and diamond back moth, aphids in cabbage and cauliflower crops. Cartap, as a pesticide has not been investigated yet for its effect on vital organs and biochemical stress in vivo and the present study was undertaken to evaluate the same in Swiss albino mice. For this purpose male mice were given three different dose levels of cartap, i.e. 5 mg/kg, 7.5 mg/kg and 15 mg/kg body weight respectively, for 28 days orally. Water was used as vehicle to dissolve cartap. Oral administration of cartap caused significant increase in serum biomarkers, tissue oxidants and decrease in antioxidants along with histopathological findings in liver, kidney and brain tissues. Thus, present study showed that in vivo exposure to cartap induces tissue damage probably via oxidative stress in important vital organs of mice.

Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements

The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP) sensor with magnetic molecularly imprinted polymeric microspheres (Fe₃O₄@mSiO₂@MIPs) as recognition elements. Using Fe₃O₄ as supporting core, mesoporous SiO₂ as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe₃O₄@mSiO₂@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe₃O₄@mSiO₂@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe₃O₄@mSiO₂@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles). The adsorption process of cartap on Fe₃O₄@mSiO₂@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1–5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe₃O₄@mSiO₂@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.

Evaluation of toxicological impact of cartap hydrochloride on some physiological activities of a non-heterocystous cyanobacterium Leptolyngbya foveolarum

The present study was aimed to the evaluation of toxicological impact of insecticide cartap hydrochloride on photosynthesis and nitrogen assimilation of a non-heterocystous cyanoprokaryote Leptolyngbya foveolarum isolated from paddy fields of Punjab, India. The microorganism tolerated commercial grade insecticide up to 80 ppm. Lower concentration (20 ppm) of cartap supported good growth with high dry weight of biomass, total protein content, photosynthetic pigments, photosynthesis and respiration compared to untreated control cultures while higher concentrations (40 and 60 ppm) inhibited these parameters in a dose dependent manner. Treatment of the microorganism with 60 ppm cartap lowered the content of photosynthetic pigments with maximum inhibitory effect on phycoerythrin (70% decrease) followed by allophycocyanin (66% decrease). Rates of photosynthesis and respiration were inhibited by 63% and 45%, respectively, while PS-I, II and whole chain activity were decreased by 45%, 67% and 40% respectively, compared to untreated control cultures. Cartap at 60 ppm decreased nitrate and nitrite uptake by 31% and 61%, respectively, whereas uptake of ammonium was slightly increased (18%) in cartap (60 ppm) treated cells. Nitrate and nitrite reductase, and glutamine synthetase activities of the microorganism decreased by 36-50% in 60 ppm cartap. The low levels of growth, photosynthetic pigments and activities of nitrogen assimilating enzymes in cells grown in nitrogen depleted medium supplement with insecticide indicated that insecticide may be used by the organism as a nitrogen source.

Highly sensitive turn-on fluorescent detection of cartap via a nonconjugated gold nanoparticle–quantum dot pair mediated by inner filter effect

The well-dispersed AuNPs exhibited a tendency to aggregate when exposed to cartap with positively charged amine groups, which induced an absorption band transition from 522 nm to the long-wavelength band, and restored the IFE-decreased emission of CdTe QDs for cartap detection.

Thimerosal-induced apoptosis in mouse C2C12 myoblast cells occurs through suppression of the PI3K/Akt/survivin pathway

Background

Thimerosal, a mercury-containing preservative, is one of the most widely used preservatives and found in a variety of biological products. Concerns over its possible toxicity have reemerged recently due to its use in vaccines. Thimerosal has also been reported to be markedly cytotoxic to neural tissue. However, little is known regarding thimerosal-induced toxicity in muscle tissue. Therefore, we investigated the cytotoxic effect of thimerosal and its possible mechanisms on mouse C2C12 myoblast cells.

Methodology/Principal Findings

The study showed that C2C12 myoblast cells underwent inhibition of proliferation and apoptosis after exposure to thimerosal (125–500 nM) for 24, 48 and 72 h. Thimerosal caused S phase arrest and induced apoptosis as assessed by flow cytometric analysis, Hoechst staining and immunoblotting. The data revealed that thimerosal could trigger the leakage of cytochrome c from mitochondria, followed by cleavage of caspase-9 and caspase-3, and that an inhibitor of caspase could suppress thimerosal-induced apoptosis. Thimerosal inhibited the phosphorylation of Akt^ser473 and survivin expression. Wortmannin, a PI3K inhibitor, inhibited Akt activity and decreased survivin expression, resulting in increased thimerosal-induced apoptosis in C2C12 cells, while the activation of PI3K/Akt pathway by mIGF-I (50 ng/ml) increased the expression of survivin and attenuated apoptosis. Furthermore, the inhibition of survivin expression by siRNA enhanced thimerosal-induced cell apoptosis, while overexpression of survivin prevented thimerosal-induced apoptosis. Taken together, the data show that the PI3K/Akt/survivin pathway plays an important role in the thimerosal-induced apoptosis in C2C12 cells.

Conclusions/Significance

Our results suggest that in C2C12 myoblast cells, thimerosal induces S phase arrest and finally causes apoptosis via inhibition of PI3K/Akt/survivin signaling followed by activation of the mitochondrial apoptotic pathway.

Stimulation of mechano-growth factor expression by second messengers

The effect of second messengers on the expression of mechano-growth factor (MGF) synthesis by myoblasts and differentiated myotubes in culture was investigated. cAMP stimulates MGF expression both in murine and human cells. CNG- and HCN-channel blockers slightly activated MGF synthesis, while an activator of Epac protein had no effect. It is assumed that cAMP activates MGF synthesis via protein kinase A. Phorbol ester (PMA) activates MGF synthesis in human myoblasts and myotubes only. The expression of another splice form of IGF-1 gene, IGF-1Ea, was also stimulated in human cells by db-cAMP and PMA and in murine cells by db-cAMP only. Stimulation of MGF expression in human cells by db-cAMP and PMA demonstrated different time dependences but showed additivity when the compounds were applied in a combination. Inhibitors specific to protein kinase A did not affect PMA-mediated activation, while inhibitors specific to protein kinase C did not affect db-cAMP-mediated process. Ca²+ ionophore and ROS inductor strongly inhibited synthesis of the growth factor. PGE2 known as physiological stimulator of cAMP synthesis was shown to stimulate MGF expression both in murine and human cells. Implication of protein kinase A and protein kinase C in MGF synthesis stimulation and a cross-talk between two signaling systems is discussed.

Induction of Ca2+ signal mediated apoptosis and alteration of IP3R1 and SERCA1 expression levels by stress hormone in differentiating C2C12 myoblasts

Glucocorticoid (GC) are stress hormones, whose cytotoxicity has been shown in various cells. The imbalance of calcium homeostasis is believed to be associated with the dexamethasone (DEX, a synthetic GC)-induced apoptosis. Here we show that in C2C12 myoblasts, DEX markedly up-regulated the expression of inositol 1,4,5-triphosphate receptor 1 (IP3R1) and down-regulated the expression of SERCA1 (sarcoendoplasmic reticulum Ca(2+)-ATPase 1), leading to calcium overload. Furthermore, the imbalance of calcium homeostasis increased the level of BAX, decreased the level of Bcl-2, induced cytochrome c release and activated caspase-3, leading to intranucleosomal DNA fragmentation and plasma membrane damage, eventually resulting in cell apoptosis. Taken together, by using C2C12 myoblasts as a model system, we demonstrated a novel mechanism for stress hormone-induced apoptosis: it is dependent on the induction of intracellular calcium overload via the alterations of IP3R1 and SERCA1 expressions.

Aquatic toxicity of cartap and cypermethrin to different life stages of Daphnia magna and Oryzias latipes

Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S'-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 microg/L and 0.00061 microg/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 microg/L and cypermethrin up to 1.9 microg/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults, which may be partly due to the protective role of the chorion. The incidence of larval fish deformity was significantly higher after a 96 hr exposure to as low as 250 microg/L of cartap or 40 microg/L of cypermethrin. The mixture of both compounds showed no synergistic toxicity. The extremely high acute-to-chronic ratio suggests that the standard acute lethal toxicity assessment might not reflect the true environmental hazards of these frequently used pesticides. Ecological hazard assessments of long-term low dose or pulsed exposures to cartap and cypermethrin may reveal more realistic consequences of these compounds in surface water.

Lewis x antigen mediates adhesion of human breast carcinoma cells to activated endothelium. Possible involvement of the endothelial scavenger receptor C-type lectin

Lewis x (Le(x), CD15), also known as SSEA-1 (stage specific embryonic antigen-1), is a trisaccharide with the structure Galbeta(1-4)Fucalpha(1-3)GlcNAc, which is expressed on glycoconjugates in human polymorphonuclear granulocytes and various tumors such as colon and breast carcinoma. We have investigated the role of Le(x) in the adhesion of MCF-7 human breast cancer cells and PMN to human umbilical endothelial cells (HUVEC) and the effects of two different anti-Le(x) mAbs (FC-2.15 and MCS-1) on this adhesion. We also analyzed the cytolysis of Le(x+)-cells induced by anti-Le(x) mAbs and complement when cells were adhered to the endothelium, and the effect of these antibodies on HUVEC. The results indicate that MCF-7 cells can bind to HUVEC, and that MCS-1 but not FC-2.15 mAb inhibit this interaction. Both mAbs can efficiently lyse MCF-7 cells bound to HUVEC in the presence of complement without damaging endothelial cells. We also found a Le(x)-dependent PMN interaction with HUVEC. Although both anti-Le(x) mAbs lysed PMN in suspension and adhered to HUVEC, PMN aggregation was only induced by mAb FC-2.15. Blotting studies revealed that the endothelial scavenger receptor C-type lectin (SRCL), which binds Le(x)-trisaccharide, interacts with specific glycoproteins of M (r ) approximately 28 kD and 10 kD from MCF-7 cells. The interaction between Le(x+)-cancer cells and vascular endothelium is a potential target for cancer treatment.