5­Aminosalicylic acid attenuates paraquat­induced lung fibroblast activation and pulmonary fibrosis of rats.

Pulmonary fibrosis is one of the most important pathological processes associated with paraquat (PQ) poisoning. 5­Aminosalicylic acid (5­ASA) has been shown to be a promising agent against fibrotic diseases. In the present study, the alleviating role of 5­ASA was evaluated in a rat model of pulmonary fibrosis induced by PQ intragastric poisoning (80 mg/kg). Wistar rats were divided into control, PQ, 5­ASA (30 mg/kg daily, 14 days) and PQ + 5­ASA groups. Histological examination revealed congestion, edema and inflammatory cell infiltration in the bronchial and alveolar walls at 3 days after PQ exposure. Alveolar septum thickening with alveolar lumen narrowing was observed at 14 days, while fibroblast proliferation, increase in collagen fiber number and fibrous thickening of the alveolar walls were observed at 28 day. All the aforementioned pulmonary injury changes in the PQ group were attenuated in the PQ + 5­ASA group. Hydroxyproline (HYP) content increased in the lung tissues of the rats at 14 days after PQ treatment and reached a peak at 28 days. Compared with the PQ group, HYP contents of lung tissue decreased at 14 and 28 days after PQ + 5­ASA treatment. Masson's trichrome staining revealed that the increase in the amount of collagen fibers in the lung tissues of rats in the PQ group was inhibited by 5­ASA treatment, further confirming the alleviating effect of 5­ASA on fibrosis. In addition, the results showed that 5­ASA attenuated the upregulation of transforming growth factor­ß1 and phosphorylated­SMAD3, and the reduction of peroxisome proliferator activated receptor γ induced by PQ in lung tissue of rats and human lung fibroblast WI­38 VA13 cells. In conclusion, the results suggested that 5­ASA had an alleviating effect on PQ­induced pulmonary fibrosis, partly by suppressing the activation of the TGF­ß1 signaling pathway.

Systemic inflammation and oxidative stress induced by inhaled paraquat in rat improved by carvacrol, possible role of PPARγ receptors.

Control rats were exposed to saline aerosol, two groups were exposed to paraquat (PQ), 27 (PQ-L) and 54 (PQ-H) mg/m3 aerosols and six groups were treated with carvacrol, 20 (C-L) and 80 (C-H) mg/kg/day, pioglitazone, 5 (Pio-L) and 10 (Pio-H) mg/kg/day, C-L+Pio-L and dexamethasone, 0.03 mg/kg/day, for 16 days after the end of exposure to PQ-H. Different variables were measured after the end of treatment period. Total and differential white blood cells counts, nitrite, malondialdehyde, interleukin (IL)-10, and interferon-gamma levels were significant increased, but thiol, superoxide dismutase, catalase, IL-17, and tumor necrosis factor alpha were decreased in the blood due to both doses of PQ (p < 0.05-p < 0.001). Most measured parameters were significantly improved in treated groups with both doses of carvacrol, pioglitazone, the combination of C-L+Pio-L and dexamethasone compared to PQ-H group (p < 0.05-p < 0.001). Treatment with C-L+Pio-L showed significantly higher effects compared to each one alone (p < 0.05-p < 0.001). Systemic oxidative stress and inflammation due to inhaled PQ were improved by carvacrol and pioglitazone. Higher effects of C-L+Pio-L than each one alone suggests carvacrol modulating PPAR-γ receptors.

Effects of ultra high dilution of paraquat 30 ch on growth, chlorophyll content and yield of rice crop

The application of synthetic fertilizers reduces the natural fertility of the soil and contaminates groundwater. Some photosynthesis inhibitors at ultra-high dilution (UHD) increase photosynthesis, growth, and yield of crops. A weedicide Paraquat at UHD enhanced the growth and yield of potatoes in fields. The objective is to see whether the UHD of Paraquat is also effective on rice. This weedicide was serially diluted with distilled water and manually succussed in 30 steps following the preparation of homeopathic dilutions called potencies. In this way, the 30thpotency of Paraquat called Paraquat 30 cH was prepared and preserved in 90 % ethanol. Paraquat 30 cH was diluted with water 1:1000 (v/v) and sprayed on rice plants in a field measuring 0.3125 acres. The control plot of the same area was situated 300 meters away from the test plot. Three treatments were given at an interval of 7 days. The treated plot showed increased growth, chlorophyll content, and rice yield significantlycompared to control. The UHD of the weedicide produced precisely the opposite effect of the crude material on plants. The increased growth and yield of rice by Paraquat 30 cH may be due to the enhancement of photosynthesis of treated plants. The UHD of Paraquat increased the yield of rice by 19.35% over the control.

Paraquat pharmacokinetics in primates and extrapolation to humans.

By extending our Paraquat (PQ) work to include primates we have implemented a modelling and simulation strategy that has enabled PQ pharmacokinetic data to be integrated into a single physiologically based pharmacokinetic (PBPK) model that enables more confident extrapolation to humans. Because available data suggested there might be differences in PQ kinetics between primates and non-primates, a radiolabelled study was conducted to characterize pharmacokinetics and excretion in Cynomolgus monkeys. Following single intravenous doses of 0.01 or 0.1 mg paraquat dichloride/kg bw, plasma PQ concentration-time profiles were dose-proportional. Excretion up to 48 h (predominantly urinary) was 82.9%, with ca. 10% remaining unexcreted. In vitro blood binding was similar across Cynomolgus monkeys, humans and rat. Our PBPK model for the rat, mouse and dog, employing a single set of PQ-specific parameters, was scaled to Cynomolgus monkeys and well represented the measured plasma concentration-time profiles over 14 days. Addition of a cartilage compartment to the model better captured the percent remaining in the monkeys at 48 h, whilst having negligible effect on model predictions for the other species. The PBPK model performed well for all four species, demonstrating there is little difference in PQ kinetics between non-primates and primates enabling a more confident extrapolation to humans. Scaling of the PBPK model to humans, with addition of a human-specific dermal submodel based on in vitro human dermal absorption data, provides a valuable tool that could be employed in defining internal dosimetry to complement human health risk assessments.

Investigation of in vivo unscheduled DNA synthesis in rabbit corneas following instillation of genotoxic agents.

PURPOSE: An unscheduled DNA synthesis (UDS) test is used for in vitro or in vivo genotoxicity evaluation. The UDS test with hepatocytes is well established; however, drug exposure levels at the application site for topically administered drugs (e.g. ophthalmic drugs) often exceed the exposure levels for systemic administration. To establish in vivo genotoxicity on the ocular surface, we performed the UDS test using rabbit corneas from eyes subjected to instillation of genotoxic agents. MATERIALS AND METHODS: Five genotoxic agents - 1,1'-dimethyl-4,4'-bipyridinium dichloride (paraquat); acridine orange; ethidium bromide; acrylamide; and 4-nitroquinoline 1-oxide (4-NQO) - were instilled once onto both eyes of male Japanese white rabbits. Physiological saline or a general vehicle for ophthalmic solution were instilled as the negative controls. Dimethyl sulfoxide was instilled as the vehicle control. Isolated corneas were incubated with tritium-labelled thymidine and the number of sparsely labelled cells (SLCs, cells undergoing UDS) was counted by autoradiography. RESULTS: Statistically significant increases in the mean appearance rates of SLCs in the corneal epithelium were noted in paraquat-, acridine orange-, ethidium bromide-, and 4-NQO-treated eyes compared with those of the controls. These increases generally appeared in a dose-dependent manner. Acrylamide did not induce an increase in the mean appearance rates of SLCs, presumably because it caused the generation of fewer metabolites in the cornea. CONCLUSIONS: UDS tests revealed DNA damage in the cornea epitheliums treated with well-known genotoxic agents. These results suggest that the UDS test is one of the useful tools for the assessment of in vivo genotoxicity on the ocular surface in the development of ophthalmic drugs.

The effect of Zataria multiflora hydroalcoholic extract on memory and lung changes induced by rats that inhaled paraquat.

Objectives: The effects of hydroalcoholic extract of Zataria multiflora (Z. multiflora) on memory changes, as well as lung injury due to inhaled paraqut (PQ) in rat, were examined.Method: Control group of rat with saline aerosol administration, PQ groups with PQ aerosol (27 and 54 mg/m3) administration, PQ groups treated with two doses of the extract (200 and 800 mg/kg/day) and dexamethasone (0.03 mg/kg/day) were studied. Shuttle box and Morris Water Maze (MWM) tests were carried out as well as oxidant, anti-oxidant markers, total and differential white blood cell (WBC) counts and cytokine levels in broncho-alveolar lavage (BALF).Results: Inhaled PQ significantly increased the escape latency and travelled distance in MWM test, but the time spent in the target quadrant on the probe day was significantly reduced (p < 0.05 to p < 0.001). The latency to enter the dark room at 3, 24, and 48 h after an electrical shock was reduced due to PQ (p < 0.05 to p < 0.001). Exposure to PQ significantly increased total WBC, neutrophil, eosinophil, lymphocyte, and monocyte counts, IL-10, interferon gama (INF-γ), nitrite (NO2), and malondialdehyde (MDA) levels, but catalase (CAT), superoxide dismutase (SOD), and thiol levels were decreased (p < 0.05 to p < 0.00). Z. multiflora and dexamethasone treatment significantly improved all behavioral as well as lung changes induced by inhaled PQ (p < 0.05 to p < 0.01).Conclusion: Z. multiflora treatment improved learning and memory impairment as well as lung inflammation and oxidative stress induced by inhaled PQ.

A novel idea for establishing Parkinson's disease mouse model by intranasal administration of paraquat.

Background: In this study, we sought to provide an idea for establishing a novel mouse model for Parkinson's disease (PD) through intranasal administration of paraquat instead of the conventional method of intraperitoneal injection. Intranasal administration has the potential to lower mortality caused by intraperitoneal paraquat administration.Methods: A paraquat-loaded thermosensitive hydrogel composed of poloxamer 407 and poloxamer 188 was prepared. The survival rate of the animals was monitored upon paraquat administration nasally and intraperitoneally. The animals' behavior was also observed. Immunofluorescence staining of tyrosine hydroxylase (TH) - positive cells and western blotting of α-synuclein (α-syn)in striatum were performed. HPLC method with electrochemical detection was used to quantify monoamine neurotransmitters in striatum. Real-time RT-PCR analysis of type 1 collagen, type 3 collagen and fibronectin expression was used to evaluate pulmonary fibrosis in mice after paraquat administration.Results: The results indicated that intranasal administration of paraquat-loaded thermosensitive hydrogel can elicit Parkinsonism-like symptoms in mice. Relative to the conventional intraperitoneal injection, this strategy significantly improves survival when modeling PD and resulted in a higher loss of TH positive neurons in substantia nigra pars compacta (SNpc) and more aggregation of α-syn in striatum. Moreover, animals receiving paraquat hydrogel nasally exhibited motor disorder as well as lower levels of dopamine and dopamine metabolites in striatum when compared to those receiving paraquat intraperitoneally. The mRNA expression of collagen and fibronectinindicated that intranasal administration of paraquat was not associated with lung fibrosis.Conclusion: This strategy provides a new idea and more convenient operation for the future study of mouse model of PD.

Paraquat exposure over generation affects lifespan and reproduction through mitochondrial disruption in C. elegans.

Paraquat (methyl viologen), is a non-selective contact herbicide and well known mitochondrial toxicant. Mitochondria are the center of cellular metabolism, and involved in the development, lifespan, and reproduction of an organism. Mitochondria are dynamic organelles that are inherited maternally through the germline and carry multiple copies of their own genome (mtDNA). It is important to understand the effects of acute and chronic stress caused by mitochondrial toxicants over multiple generations at the cellular and organism levels. Using the model nematode C. elegans, we show that acute and chronic exposure to paraquat affects reproduction, longevity, gene expression, and mitochondrial physiology. Acute exposure to paraquat in N2 (wild type) causes induction of mitochondrial unfolded protein response (mtUPR), increased expression of mitochondrial superoxide dismutase, decreased mitochondrial membrane potential (Δψm), a dose-dependent progression from linear to fragmented mitochondria, and dose-dependent changes in longevity. Chronic exposure to a low dose of paraquat (0.035 mM) over multiple generations in N2 causes a progressive decline of fertility, leading to complete loss of fertile embryo production by the third generation. The mutation in CEP-1 [cep-1(gk138)], a key regulator of stress-induced apoptosis in the germline, causes increased sensitivity to chronic paraquat relative to N2 with no fertile embryo production beyond the second generation. Whereas, mitochondrial electron transport chain (complex III) mutant [isp-1(qm150)], which display constitutive activation of mtUPR showed increased tolerance and produced fertile embryo out to the fourth generation. The N2, cep-1(gk138), and isp-1(qm150) strain's lifespan over multiple generations exposed to chronic paraquat were measured. Fertility and lifespan data together indicate a trade-off between reproduction and somatic maintenance during chronic paraquat exposure. We have proposed that mitochondrial signaling, dynamics, and CEP-1 mediated germline apoptosis is involved in this trade-off.

The Ocular Protective Effects of Nano/Submicron Particles Prepared from Lycium barbarum Fruits Against Oxidative Stress in an Animal Model.

Purpose: To investigate the antioxidative properties of Lycium barbarum (LB) fruits in the eyes and to study whether LB fruits prepared with new nanotechnology have stronger antioxidative effects. Methods: Fourteen days post-supplementation with milled or blended LB fruits, intravitreal paraquat (PQ) was injected into Wistar rats to create oxidative stress. After an additional 14-day supplementation with LB fruits, the rats were sacrificed. An electroretinogram (ERG) was performed to evaluate retinal function before and after the PQ injection. Expression levels of antioxidative responders' mRNA in retina were detected by reverse transcription-polymerase chain reaction. Superoxide dismutase (SOD) and glutathione reductase activity in the aqueous humor (AqH) were analyzed by ELISA. Immunohistochemistry was conducted to evaluate the morphological changes of retina and the levels of oxidative biomarkers. The levels of cell apoptosis were assessed by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The reactive oxygen species (ROS) levels in AqH were measured by chemiluminescence methods. Results: The murine eyes supplemented with LB fruits exhibited several changes compared with the control group. The ERGs revealed significant improvement in retinal function. The mRNA expression levels of oxidative responders were downregulated in the retinas. The ROS was significantly reduced in the retinas, but the SOD meaningfully increased in the AqH. Immunohistochemistry staining and TUNEL assays showed decreased incidences of oxidative biomarkers and apoptosis in the retinas. Milled LB fruits exhibited better antioxidative effects than blended fruits. Conclusions: Milled LB fruits demonstrated superior protection against oxidative threats than blended fruits. Thus, these fruits could be an inexpensive supplement for many oxidative stress-related ocular diseases.

Efecto de la n-acetilcisteina inhalada en el desarrollo de fibrosis pulmonar de ratas intoxicadas con paraquat / Effect of n-acetylcisteine inhaled in the development of pulmonary fibrosis of intoxicated rats with paraquat

El Paraquat (PQ) es un herbicida de contacto bipiridilico ampliamente utilizado en agricultura. La intoxicación en humanos por este agente ocasiona fibrosis pulmonar. Evaluamos los cambios histológicos pulmonares de ratas intoxicadas con PQ y tratadas con N-aceticisteina (NAC) administrada vía inhalatoria. Realizamos un estudio experimental descriptivo con 25 ratas adultas, machos cepa Wistar, divididas en cinco grupos. Al grupo I no se les administro ni PQ ni NAC. Grupo II, recibió NAC inhalada a 15mg/kg diaria c/12 horas. Grupo III, PQ vía oral (VO) 15mg/kg. Grupo IV, PQ a 15mg/kg, por VO y a la hora NAC 150mg/kg. Grupo V, PQ a 15mg/kg, por VO y a las seis horas NAC dosis de 150mg/kg. Los pulmones fueron extraídos y se evaluaron mediante cortes histológicos. Resultados: Los grupos I y II (supervivencia del 100%, n=10) no desarrollaron sintomatología de intoxicación. Grupos III, IV y V predominaron síntomas respiratorios, diversos grados de edema pulmonar, enfisema, congestión vascular y hemorragia intra-alveolar focal. La eficacia de la NAC sobre la intoxicación por PQ en términos de sobrevivencia al primer día, fue del 100% y al segundo día, fue del 80% (p= 0,005; prueba Chi-cuadrado). El PQ indujo un proceso inflamatorio (agudo-crónico) por infiltrado de segmentados neutrófilos y linfocitos, lo cual fue revertido parcialmente por la administración inhalada de NAC. Conclusión: Los cambios histopatológicos observados a nivel pulmonar fueron aminorados por el tratamiento con NAC, lo que sugiere un posible efecto protector de este fármaco sobre el daño oxidativo inducido por el herbicida

Paraquat (PQ) is a bipyridyl contact herbicide widely used in agriculture. Intoxication in humans by this agent causes pulmonary fibrosis. We evaluated pulmonary histological changes of rats intoxicated with PQ and treated with N-acetycysteine (NAC) administered via inhalation. We conducted a descriptive experimental study with 25 adult rats, male Wistar strain, divided into five groups. Group I was not administered PQ or NAC. Group II, received NAC inhaled at 15mg/kg daily c/12 hours. Group III, PQ orally (VO) 15mg/ kg. Group IV, PQ at 15mg/kg, by VO and at hour NAC 150mg/ kg. Group V, PQ at 15mg/kg, by VO and at six hours NAC dose of 150mg/kg. The lungs were extracted and evaluated by histological sections. Results: Groups I and II (100% survival, n=10) did not develop intoxication symptoms. Groups III, IV and V predominantly respiratory symptoms, various degrees of pulmonary edema, emphysema, vascular congestion and focal intra-alveolar hemorrhage. The efficacy of NAC on PQ poisoning in terms of survival on the first day was 100% and on the second day it was 80% (p = 0.005, Chi-square test). The PQ induced an inflammatory process (acute-chronic) by infiltration of segmented neutrophils and lymphocytes, which was partially reversed by the inhaled administration of NAC. Conclusion: The histopathological changes observed at the pulmonary level were reduced by the treatment with NAC, which suggests a possible protective effect of this drug on the oxidative damage induced by the herbicide.

Ameliorative role of aspirin in paraquat-induced lung toxicity via mitochondrial mechanisms.

Paraquat (PQ) has accounted for numerous suicide attempts in developing countries. Aspirin (ASA) as an adjuvant treatment in PQ poisoning has an ameliorative role. And, it's uncoupling of mitochondrial oxidative phosphorylation role has been well established. The current study aimed at examining the aspirin mechanism on lung mitochondria of rats exposed to PQ. Male rats were randomly allocated in five groups: Control group, PQ group (50 mg/kg; orally, only on the first day), and PQ + ASA (100, 200, and 400 mg/kg; i.p.) groups for 3 weeks. Mitochondrial indices and respiratory chain-complex activities were determined. PQ induced lung interstitial fibrosis; however, ASA (400 mg/kg) led to decrease in this abnormal alteration. In comparison with PQ group, complex II and IV activity, and adenosine triphosphate content in ASA groups had significantly increased; however, reactive oxygen species production, mitochondrial membrane permeabilization, and mitochondrial swelling were significantly reduced. In conclusion, aspirin can alleviate lung injury induced by PQ poisoning by improving mitochondrial dynamics.

Reduning injection ameliorates paraquat-induced acute lung injury by regulating AMPK/MAPK/NF-κB signaling.

Reduning injection (RDN), a patented Chinese medicine, is broadly used for common cold and lung infection in clinic, but the mechanism underlying its effects on inflammation-related pulmonary injury remains unclear. Paraquat (PQ, bolus 15 mg/kg dose, ip) was administered for acute lung injury induction in mice, which were orally administered dexamethasone (2 mg/kg) or RDN (50 and 100 mg/kg/day) for 5 days. After treatment, plasma and lung tissue samples from the euthanized animals were obtained and analyzed by histological, biochemical and immunoblot assays. Histological observation demonstrated RDN alleviated PQ-induced lung damage. Meanwhile, RDN suppressed myeloperoxidase (MPO) activity, reduced the wet/dry (W/D) ratio and decreased the amounts of total leukocytes and neutrophils. Treatment also markedly decreased the amounts of malondialdehyde, MPO, and inflammatory cytokines while increasing superoxide dismutase activity in comparison with the PQ group. In immunoblot, RDN blocked the phosphorylation levels of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), JNK, ERK, p38, inhibitor of nuclear factor κB kinase and nuclear factor-κB (NF-κB) in lung tissue specimens in PQ-challenged animals, which was further verified in vitro. The above data indicated protective effects for RDN in PQ-induced lung damage, possibly through inhibition of the AMPK/MAPK/NF-κB pathway.

Does juvenile hormone prompt oxidative stress in male damselflies?

In invertebrates, it has recently been reported that secondary sexual characteristics (SSCs) reflect the antioxidant defense of their bearers, but it is not known what physiological link maintains the honesty of those signals. Here, we used the damselfly Hetaerina americana to test whether juvenile hormone plays such a role. First, we analyzed whether oxidative damage is a real threat in natural damselfly populations by examining the accumulation of oxidized guanines as a function of age in males. Then, we injected paraquat (a pro-oxidant agent) and added the juvenile hormone analog methoprene (JHa) to the experimental group and the JHa vehicle (acetone) to the control group, to determine whether JHa increases the levels of pro-oxidants and antioxidants. We found that DNA oxidation increased with age, and that levels of hydrogen peroxide and superoxide dismutase, but not catalase or glutathione, were elevated in the JHa group compared with the control group. We propose that juvenile hormone is a mediator of the relationship between SSCs and antioxidant capacity and, based on the literature, we know that JHa suppresses the immune response. We therefore suggest that juvenile hormone is a molecular mediator of the general health of males, which is reflected in their SSCs.

Redox state affects fecundity and insecticide susceptibility in Anopheles gambiae.

Redox reactions play a central role in the metabolism of an organism. It is vital to maintain redox homeostasis in response to the fluctuation of redox shift in various biological contexts. NADPH-dependent reducing capacity is one of the key factors contributing to the redox homeostasis. To understand the redox capacity and its impact on mosquito fecundity and susceptibility to insecticides in Anopheles gambiae, we examined the dynamics of elevated oxidative state via induction by paraquat (PQ) and the inhibition of NADPH regeneration by 6-aminonicotinamide (6AN). In naïve conditions, inherent oxidative capacity varies between individuals, as measured by GSSG/GSH ratio. The high GSSG/GSH ratio was negatively correlated with fecundity. Both PQ and 6AN feeding increased GSSG/GSH ratio and elevated protein carbonylation, a marker of oxidative damage. Both pro-oxidants lowered egg production. Co-feeding the pro-oxidants with antioxidant lycopene attenuated the adverse effects on fecundity, implying that oxidative stress was the cause of this phenotype. Pre-feeding with 6AN increased insecticide susceptibility in DDT resistant mosquitoes. These results indicate that oxidative state is delicate in mosquitoes, manipulation of NADPH pool may adversely affect fecundity and insecticide detoxification capacity. This knowledge can be exploited to develop novel vector control strategies targeting fecundity and insecticide resistance.

A survival case of intravenous paraquat intoxication: A case report.

RATIONALE: Paraquat, an agent highly toxic to humans and animals, is a widely used herbicide and also commonly used for suicide attempts in Taiwan. The most common route of intoxication is oral ingestion, and parenteral poisoning is respectively rare. PATIENT CONCERNS: A 39-year-old illicit abuser of heroin and amphetamine injected 0.5 mL of 24% paraquat directly into his right cephalic vein due to hallucination. The patient was brought to our emergency department for management 4 hours after injection. He was fully conscious and had normal vital signs. Systemic review showed mild dyspnea, abdominal pain and right wrist pain over the injection site. The only abnormal physical finding was erythema over the injection site and epigastric tenderness. DIAGNOSIS: Laboratory investigations, including complete blood count, liver and renal function, and electrolytes initially yielded normal results. Urinalysis showed normal findings except a positive urine paraquat test (4+). The initial plasma paraquat concentration was 0.51 µg/mL. INTERVENTIONS: He was admitted to the intensive care unit and underwent one session of charcoal hemoperfusion therapy. Acute kidney injury developed on the fourth day after intoxication, with the level of serum creatinine rising rapidly from 0.96 to 4.57 mg/dL and the daily urine output decreased noticeably from > 2000 to 900 mL. The serum creatinine level improved gradually with adequate fluid supplementation. OUTCOMES: The patient was discharged 13 days later in a stable condition. LESSONS: Intravenous paraquat intoxication is rare. Patients who suffer from intravenous intoxication may not directly suffer from mucosal irritation, but the clinical onset of systemic effects is more immediate and lethal. The prognosis of paraquat poisoning is determined by the time of poisoning and the plasma paraquat concentration before treatment. Proudfoot's curve provides a simple method of predicting the survival rate. The most effective mode of management is extracorporeal therapy, and immunosuppressive or antioxidant therapies have shown insufficient evidence of benefit.

Protective role of thymoquinone against paraquat-induced hepatotoxicity in mice.

Paraquat is a common and effective herbicide; although its poisoning could lead to severe oxidative organ damages and its main target organs are the lungs, kidneys, heart, and liver. Thymoquinone is the active ingredient of Nigella sativa which is traditionally used in herbal medicine; recent studies have shown that thymoquinone could inhibit oxidative stress. This study explores protective effects of thymoquinone on paraquat-induced hepatotoxicity in mice. Accordingly, adult male mice were randomly divided into nine groups for three continuous days intraperitoneal injection treatment: (1) control; (2) solvent; (3) 20 mg/kg vitamin E; (4) 20 mg/kg thymoquinone; (5) 20 mg/kg paraquat and Groups 6, 7, 8, and 9 received 20 mg/kg of vitamin E and 5, 10, and 20 mg/kg of thymoquinone, respectively. The last four groups, received 20 mg/kg paraquat just 24 h after pretreatments. We assessed serum liver enzymes activities, liver histopathology changes, oxidative (lipid peroxidation) and antioxidative (ferric reducing antioxidant power) potential, superoxide dismutase (SOD) and catalase activity, and total thiol groups content after administration of the poison and treatments. Pretreatment with 10 mg/kg thymoquinone inhibited, safely, the elevations in levels of liver function tests (LFTs) and lipid peroxidation, restored the activity of SOD, and ameliorated the histopathological alterations induced by paraquat. Eventually, our results indicate that thymoquinone performs its hepatoprotective role in mice by prevention of SOD suppression mediated by paraquat.

Determinação de paraquate em batatas / Determination of paraquat in potatoes

O Paraquate (1,1'-dimetil-4,4'-bipiridina- dicloreto) é herbicida amplamente utilizado em vários países para diferentes culturas. O objetivo é determinar a concentração de Paraquate em batatas comercializadas em diferentes estabelecimentos da zona leste de São Paulo. Foram coletadas 12 (doze) amostras de batatas adquiridas no comércio varejista (sacolões, ou seja, do de frutas, verduras e legumes; supermercados e feiras livres) da zona leste do município de São Paulo. A quantificação do Paraquate foi baseada na reação de complexação com o ditionito de sódio, gerando composto de cor azulada, cuja absorvância foi lida em espectrofotômetro em comprimento de onda de 600nm. Foi construída a curva padrão e a determinada a equação da reta (y = 1,6448x e R2= 0,9945). O limite de tolerância do herbicida em alimentos é de 0,2 partes por milhão ou 0,2 mg/kg, enquanto que a ingestão diária aceitável (IDA) é de 0,004 mg/kg de peso corpóreo. Assim, pode-se observar que os valores encontrados em três amostras estão acima do limite máximo permitido, enquanto quatro apresentaram concentrações muito próximas ao limite. Os resultados permitem inferir que existe a necessidade de intensificação na fiscalização nos locais de comercialização de alimentos produzidos com a utilização de agrotóxicos.(AU)

Paraquat (1,1'-dimethyl-4,4'- bipyridine-dichloride) is herbicide widely used in several countries in different plantations. The objective is to determine the concentration of Paraquat in potatoes, marketed in different establishments in the eastern zone of São Paulo. Twelve (12) samples of potatoes purchased from the retail trade ("sacolões", ie fruit, vegetable and vegetable markets, supermarkets and free markets) were collected from the eastern part of the city of São Paulo. The quantification of Paraquat was based on the reaction of complexation with the sodium dithionite, generating compound of blue color, whose absorbance was read in a spectrophotometer at wavelength of 600 nm. The standard curve was constructed and the equation of the line was determined (y = 1,6448x e R2 = 0,9945). The tolerance limit of the herbicide in foods is 0.2 parts per million or 0.2 mg/kg, while the acceptable daily intake (ADI) is 0.004 mg/kg body weight. Thus, it can be observed that the values found in three samples are above the maximum allowed limit, while four of them presented concentrations very close to the limit. The results allow inferring that there is a need for intensification in the inspection in the commercial places of food produced with the use of pesticides.

Oral Exposure to Paraquat Triggers Earlier Expression of Phosphorylated α-Synuclein in the Enteric Nervous System of A53T Mutant Human α-Synuclein Transgenic Mice.

The misfolded α-synuclein protein, phosphorylated at serine 129 (pSer129 α-syn), is the hallmark of Parkinson disease (PD). Detected also in the enteric nervous system (ENS), it supports the recent theory that PD could start in the gut, rather than the brain. In a previous study, using a transgenic mouse model of human synucleinopathies expressing the A53T mutant α-synuclein (TgM83), in which a neurodegenerative process associated with α-synuclein occurs spontaneously in the brain, we have shown earlier onset of pSer129 α-syn in the ENS. Here, we used this model to study the impact of paraquat (PQ) a neurotoxic herbicide incriminated in PD in agricultural workers) on the enteric pSer129 α-syn expression in young mice. Orally delivered in the drinking water at 10 mg/kg/day for 6-8 weeks, the impact of PQ was measured in a time-dependent manner on weight, locomotor abilities, pSer129 α-syn, and glial fibrillary acidic protein (GFAP) expression levels in the ENS. Remarkably, pSer129 α-syn was detected in ENS earlier under PQ oral exposure and enteric GFAP expression was also increased. These findings bring additional support to the theory that neurotoxic agents such as PQ initiate idiopathic PD after oral delivery.

The toxic influence of paraquat on hippocampal neurogenesis in adult mice.

Paraquat, a fast-acting non-selective contact herbicide, is considered an etiological factor related to Parkinson's disease. This study investigated its effects on hippocampal neurogenesis and cognition in adult mice as well as possible mechanisms for the effects. We administered paraquat (1.25 mg/kg, intraperitoneal injection, i.p.) and an equal volume of normal saline for 3 weeks to adult male C57BL/6J mice. The results showed that hippocampus-dependent spatial learning and memory was significantly impaired in paraquat-treated mice. Moreover, paraquat administration inhibited the proliferation of neural progenitor cells, and impaired the survival and altered the fate decision of newly generated cells in the hippocampus. The expression levels of caspase-3 and glial fibrillary acidic protein were significantly higher in paraquat-treated mice than in control mice. Interestingly, paraquat reduced the phosphorylation of Akt, but did not affect the total amount of Akt. In conclusion, our findings suggest that paraquat negatively affected adult hippocampal neurogenesis and cognition function.

Mechanisms of defense against products of cysteine catabolism in the nematode Caenorhabditis elegans.

Cysteine catabolism presents cells with a double-edged sword. On the one hand, cysteine degradation provides cells with essential molecules such as taurine and sulfide. The formation of sulfide in cells is thought to regulate important and diverse physiological processes including blood circulation, synaptic activity and inflammation. On the other hand, the catabolism of cysteine by gut microbiota can release high levels of sulfide that may underlie the development or relapse of ulcerative colitis, an inflammatory bowel disease affecting millions of people worldwide. Here, we have used the nematode C. elegans to explore how cells tolerate high levels of sulfide produced by cysteine degradation in bacteria. We have identified mutations in genes coding for thioredoxin family proteins, mitochondrial proteins, and collagens that confer tolerance to sulfide toxicity. Exposure to sulfide induces the unfolded protein response in the endoplasmic reticulum and mitochondria. Moreover, our results suggest that sulfide toxicity is mediated by reactive oxygen species (ROS). Indeed, pre-treatment of worms with antioxidants increases their tolerance to sulfide toxicity. Intriguingly, sub-toxic levels of the superoxide generator paraquat can also increase the tolerance of worms to sulfide. Therefore, it appears that activation of ROS detoxification pathway prior to the exposure to sulfide, can increase the tolerance to sulfide toxicity. Our results suggest that these detoxification pathways are mediated by the hypoxia inducible factor HIF-1. Finally, we show that sulfide resistance varies among wild C. elegans and other nematode species, suggesting that tolerance to sulfide was naturally selected in certain habitats.