Effect of lindane on hepatic and brain cytochrome P450s and influence of P450 modulation in lindane induced neurotoxicity

Glutamatergic transmission associated with locomotion-related neurotoxicity to lindane over generations in Caenorhabditis elegans

Organochlorine pesticide lindane in the environment and biota results in the potential risks on ecosystem and human health. Lindane can adversely affect the locomotion and nervous system, yet the potential neurotoxicity of lindane over generations remains uncertain. In this study, the neurotoxicity and underlying mechanisms in Caenorhabditis elegans (C. elegans) were investigated after parental (P0) exposure to lindane at environmentally relevant concentrations over generations. Exposure to lindane at concentrations of 10-100 ng/L significantly decreased body bends and head thrashes in P0 generation. Significant decrease of fluorescence labeled different neurotransmitters, and clear morphological changes by exposure to lindane at 10-100 ng/L suggested that lindane could induce the neuronal damage in C. elegans. During the transgenerational process, decreased locomotive behaviors were also observed in F1-F3 generations, and head thrashes returned to normal levels in F4 generation. Moreover, lindane exposure down-regulated the expression of dat-1, dop-1, glr-1 and mod-1genes, while up-regulated unc-30 gene in P0 generation, which recovered to normal levels in F4 generation. Interestingly, eat-4 continued to be regulated from inhibition to stimulation in P0-F4 generations, suggesting that glutamatergic transmission may more contribute to the neurotoxicity of lindane over generations.

Grape seed alleviates lindane-induced oxidative stress and improves growth performance, caecal fermentation and antioxidant capacity in growing rabbits

This study evaluated the protective effect of grape seed on performance, caecal characteristics, blood metabolites and liver antioxidant status in lindane-treated rabbits. Four-week-old New Zealand White rabbits (n = 96) with an initial body weight of 0.750 ± 0.23 g were randomly divided into four groups (n = 24). One group was the control received only corn oil orally, while group L were received lindane daily via gavage in corn oil (4 mg/kg BW; 1/50 LD₅₀ for oral dose), group GS was treated with 50 g grape seed /kg diet, and group LGS treated with a combination of both L and GS for 98 days. Results revealed that final body weight (FBW), average daily gain (ADG), dry matter intake and feed efficiency (FE) were similar between GS and control groups, and achieved the highest FBW and ADG, and the best FE. Caecum pH of the L group increased, while the caecum pH of the GS group decreased sharply. There was a significant increase in the concentration of total VFA, acetic acid, propionic acid and NH₃ -N in the GS group, but butyric acid level decreased. GS treatment resulted in a significant increase in the concentrations of total protein, albumin and AChE. GPx, GST, CAT and SOD activity decreased, but TBARS activity significantly increased in the group L, while GS caused a significant elevation of antioxidant activity in the liver. These results confirm that the antioxidant compounds present in grape seed can alleviate the oxidative stress caused by lindane-induced hepatotoxicity and could be a useful supplement to maintain health and improve performance in rabbits.

Long-term toxicity of lindane through oxidative stress and cell apoptosis in Caenorhabditis elegans

Lindane persists in the environment and bioaccumulates as an organochlorine pesticide and can pose risks to ecological environments and human health. To explore the long-term toxicity and underlying mechanisms of lindane, Caenorhabditis elegans was chosen as an animal model for toxicological study. The indicators of physiological, oxidative stress and cell apoptosis were examined in nematodes chronically exposed to environmentally relevant concentrations of lindane (0.01-100 ng/L). The data suggested that exposure to lindane at doses above 0.01 ng/L induced adverse physiological effects in C. elegans. Significant increases of ROS production and lipofuscin accumulation were observed in 100 ng/L of lindane-exposed nematodes, suggesting that lindane exposure induced oxidative stress in nematodes. Exposure to 10-100 ng/L of lindane also significantly increased the average number of germ cell corpses, which indicated cell apoptosis induced by lindane in C. elegans. Moreover, chronic exposure to 100 ng/L lindane significantly influenced the expression of genes related to oxidative stress and cell apoptosis (e.g., isp-1, sod-3, ced-3, and cep-1 genes). These results indicated that oxidative stress and cell apoptosis could play an important role in toxicity induced by lindane in nematodes.

Rapid and Sensitive Quantification of the Pesticide Lindane by Polymer Modified Electrochemical Sensor

Lindane is documented by the Environmental Protection Agency (EPA) as one of the most toxic registered pesticides. Conventional detection of lindane in the environment requires manual field sampling and complex, time-consuming analytical sample handling relying on skilled labor. In this study, an electrochemical sensing system based on a modified electrode is reported. The system is capable of detecting lindane in aqueous medium in only 20 s. The surface of a conventional carbon electrode is modified with a film of conductive polymer that enables detection of lindane down to 30 nanomolar. The electrode modification procedure is simple and results in a robust sensor that can withstand intensive use. The sensitivity of the sensor is 7.18 µA/µM and the performance was demonstrated in the determination of lindane in spiked ground water. This suggests that the sensor is potentially capable of providing useful readings for decision makers. The rapid and sensitive quantification of lindane in aqueous medium is one step forward to new opportunities for direct, autonomous control of the pesticide level in the environment.

Toxicity of lindane induced by oxidative stress and intestinal damage in Caenorhabditis elegans

Lindane, a lipophilic pollutant, may be toxic to organisms. To explore the toxic effects of lindane and the underlying mechanisms of this toxicity, the animal model Caenorhabditis elegans (C. elegans) was exposed to lindane for 3 d at environmentally relevant concentrations (0.01-100 ng/L) and the physiological, biochemical, and molecular indices were evaluated. Subacute exposure to 10-100 ng/L of lindane caused adverse physiological effects on the development, reproduction, and locomotion behaviors in C. elegans. Exposure to 1-100 ng/L of lindane increased the accumulation of Nile red and blue food dye, which suggested high permeability of the intestine in nematodes. Lindane exposure also significantly influenced the expression of genes related to intestinal development (e.g., mtm-6 and opt-2). Moreover, reactive oxygen species production, lipofuscin accumulation, and expression of oxidation resistance genes (e.g., sod-5 and isp-1) were significantly increased in C. elegans exposed to 10-100 ng/L of lindane, which indicated that lindane exposure induced oxidative stress. According to Pearson correlation analyses, oxidative stress and intestinal damage were significantly correlated with the adverse physiological effects of lindane. Therefore, the adverse effects of lindane may have been induced by intestinal damage and oxidative stress, and mtm-6, opt-2, sod-5, isp-1, and mev-1 might play important roles in the toxicity of lindane.

Residential exposure to pesticides as risk factor for childhood and young adult brain tumors: A systematic review and meta-analysis

BACKGROUND

Accumulating evidence suggests a positive association between exposure to non-agricultural pesticides and childhood brain tumors (CBT).

OBJECTIVE

(1) To conduct a systematic review and meta-analysis of published studies on the association between residential/household/domestic exposure to pesticides and childhood brain tumors. (2) To clarify variables that could impact the results.

METHODS

Publications in English were identified from a MEDLINE search through 28 February 2017 and from the reference list of identified publications. Risk estimates were extracted from 18 case-control studies published between 1979 and 2016 and study quality assessments were performed. Summary odds ratios (mOR) were calculated according to fixed and random-effect meta-analysis models. Separate analyses were conducted after stratification for study quality, critical exposure period, exposure location, specific exposures, pesticide category, application methods, type of pest treated, type of CBT, child's age at diagnosis and geographic location.

RESULTS

Statistically significant associations were observed with CBT after combining all studies (mOR: 1.26; 95% CI: 1.13-1.40) without evidence of inconsistency between study results or publication bias. Specifically, increased risks were observed for several groupings and more particularly for gliomas and exposure involving insecticides. Statistical significance was also reached for high quality studies, for all exposure periods, for indoor exposure and, more particularly, during the prenatal period for all stratifications involving insecticides (except for outdoor use), for pet treatments, for flea/tick treatment, for studies from USA/Canada and studies from Europe (borderline) as well as for data from studies including children of up to 10years at diagnosis and of up to 15years.

CONCLUSIONS

Our findings support an association between residential exposure to pesticides and childhood brain tumors. Although causality cannot be established, these results add to the evidence leading to recommend limiting residential use of pesticides and to support public health policies serving this objective.

Cell type-specific expression and localization of cytochrome P450 isoforms in tridimensional aggregating rat brain cell cultures

Within the Predict-IV FP7 project a strategy for measurement of in vitro biokinetics was developed, requiring the characterization of the cellular model used, especially regarding biotransformation, which frequently depends on cytochrome P450 (CYP) activity. The extrahepatic in situ CYP-mediated metabolism is especially relevant in target organ toxicity. In this study, the constitutive mRNA levels and protein localization of different CYP isoforms were investigated in 3D aggregating brain cell cultures. CYP1A1, CYP2B1/B2, CYP2D2/4, CYP2E1 and CYP3A were expressed; CYP1A1 and 2B1 represented almost 80% of the total mRNA content. Double-immunolabeling revealed their presence in astrocytes, in neurons, and to a minor extent in oligodendrocytes, confirming the cell-specific localization of CYPs in the brain. These results together with the recently reported formation of an amiodarone metabolite following repeated exposure suggest that this cell culture system possesses some metabolic potential, most likely contributing to its high performance in neurotoxicological studies and support the use of this model in studying brain neurotoxicity involving mechanisms of toxication/detoxication.

Similarities in lindane induced alteration in cytochrome P450s and associated signaling events in peripheral blood lymphocytes and brain

Studies were initiated to investigate the similarities in alterations in cytochrome P450s (CYPs) and associated signaling events in brain and peripheral blood lymphocytes (PBL) induced by lindane, an organochlorine pesticide. Adult male albino wistar rats were treated orally with different doses (2.5- or 5.0- or 10- or 15 mg/kg/body weight) of lindane daily for 4 days. In another experiment, the treatment of low dose (2.5mg/kg) of lindane was continued for 15- and 21 days. A dose- and time-dependent increase was observed in the activity of CYP dependent enzymes in brain microsomes and PBL isolated from the treated rats. However, the magnitude of induction was several folds less in PBL. As observed in brain, RT-PCR and Western immunoblotting demonstrated that increase in CYP enzymes in PBL is due to the increase in the mRNA expression of specific CYP isoenzymes. Similarities were also observed in activation of ERK and JNK MAP kinases and c-jun in PBL or brain isolated from rats treated with lindane. Similarities in the induction of CYPs and activation of MAP kinases in PBL and brain suggest that CYP expression profiles in PBL could be used for monitoring the exposure and toxicity of environmental chemicals.

A combination of ascorbic acid and α-tocopherol or a combination of Mg and Zn are both able to reduce the adverse effects of lindane-poisoning on rat brain and liver

The purpose of this study, carried out on male Wistar rats, was to evaluate the beneficial effects of supplementation with ascorbic acid (Vit C) and α-tocopherol (Vit E) or with Mg and Zn upon lindane-induced damages in liver and brain. Under our experimental conditions, lindane poisoning (5mg/kg body weight per day for 3 days) resulted in (1) an increased level of plasma glucose, cholesterol and triglycerides, (2) an increased activity of LDH, ALP, AST, ALT, (3) an oxidative stress in liver and brain as revealed by an increased level of lipids peroxidation (TBARS) and a decrease of glutathione-peroxidase, superoxide dismutase and catalase activities in liver and brain. In conclusion, both Vit C+E or Mg+Zn treatments display beneficial effects upon oxidative stress induced by lindane treatment in liver and brain.

Molecular investigation of the effects of lindane in rat hepatocytes: microarray and mechanistic studies

Although many studies of lindane toxicity have been carried out, we still know little about the underlying molecular mechanisms. We used a microarray specifically designed for studies of the hepatotoxic effects of xenobiotics to evaluate the effects of lindane on specific gene expression in primary cultured rat hepatocytes. These genes were assigned to detoxication processes (CYP3A4, Gsta2, CYP4A1), cell signalling pathways and apoptosis (Eif2b3, Eif2b4, PKC). In this study, we demonstrate that lindane up-regulates PKC by increasing oxidative stress. TEMPO (a well known free radical scavenger) and Ro 31-8220 (an inhibitor of classical PKCs) prevented the inhibition of spontaneous and intrinsic apoptosis pathway (characterised by Bcl-xL induction, Bax down-regulation, caspases inhibition) and the induction of necrosis by lindane in rat hepatocytes. Thus, these findings indicate that several dependent key signalling pathways, including detoxification, apoptosis, PKC activity and redox status maintenance, contribute to lindane-induced toxicity in primary cultured rat hepatocytes. This may account more clearly for the acute and chronic effects of lindane in vivo, with the induction of cell death and tumour promotion, respectively.

Oxidative stress in liver and red blood cells in acute lindane toxicity in rats

The aim of our study was to determine the role and dynamics of oxidative and nitrosative stress, as well as superoxide dismutase (SOD) and catalase activity in the hepatocytes and erythrocytes in early phase of acute lindane intoxication. Male Wistar rats were divided into groups: control, dimethylsulfoxide and lindane-treated groups (L, 8 mg/kg, intraperitoneally). Animals were sacrificed 0.5 and 4 hours after treatment (L(0.5) and L(4) groups, respectively). Oxidative and nitrosative stress parameters and antioxidant enzymes were determined spectrophotometrically. Liver and plasma thiobarbituric acid reactive substances (TBARS) concentration were significantly increased 0.5 after lindane administration (p < .01), with subsequent additional rise within 4 hours (p < .01), while plasma nitrite + nitrate level was significantly higher only 4 hours after lindane treatment. Total liver SOD activity was significantly increased in L(4) group in comparison with control group (p < .01). In conclusion, oxidative and nitrosative stress play an important role in early phase of acute lindane hepatotoxicity. Antioxidant capacity of hepatocytes is partly increased, due to an adaptive increase in SOD activity.

Phenotype of hepatic xenobiotic metabolizing enzymes and CYP450 isoforms of sanguinarine treated rats: effect of P450 inducers on its toxicity

Catalytic and immunochemical activities of cytochrome P450 (CYP) isoforms were investigated in argemone alkaloid, sanguinarine (SAN) intoxicated rats, pre-treated with different CYP inducers. SAN treated control (CON) and ethanol (ET), 3- methylcholantherene (MC) or dexamethasone (DEX) pre-exposed rats, resulted in 48, 64, 47 and 33% decrease in CYP content. SAN exposure to CON, and DEX, MC or ET pre-treated animals caused a decrease (22-37%) in glutathione-S-transferase (GST) activity, however, quinone reductase (QR) activity decreased (26-45%) in the MC pre-exposed group. Similarly, western-blot analysis of hepatic CYP1A1 and CYP1A2 showed a decrease (27-37%) in MC pre-treated SAN exposed animals. Further, a decrease in mortality in the SAN+MC (25%) group compared to SAN treated animals was also observed. The results suggest that inhibition of CYP 1A1, 1A2, 2D1, 2E1, 3A1, and Phase II enzymes by SAN augments its toxicity, whereas attenuation of SAN toxicity by MC may be due to removal of parent compound/metabolites from the body.

Xenobiotic-metabolizing cytochromes p450 in human white adipose tissue: expression and induction

Lipophilic pollutants can accumulate in human white adipose tissue (WAT), and the consequences of this accumulation are still poorly understood. Cytochromes P450 (P450s) have recently been found in rat WAT and shown to be inducible through mechanisms similar to those in the liver. The aim of our study was to describe the cytochrome P450 pattern and their induction mechanisms in human WAT. Explants of subcutaneous and visceral WAT and primary culture of subcutaneous adipocytes were used as WAT models, and liver biopsies and primary culture of hepatocytes were used as liver models to characterize P450 expression in both tissues. The WAT and liver models were then treated with typical P450 inducers (rifampicin, phenobarbital, and 2,3,7,8-tetrachlorodibenzo-p-dioxin) and lipophilic pollutants (lindane, prochloraz, and chlorpyrifos), and the effects on P450 expression were studied. P450 expression was considerably lower in WAT than in the liver, except for CYP1B1 and CYP2U1, which were the most highly expressed adipose P450s in all individuals. 2,3,7,8-Tetrachlorodibenzo-p-dioxin and prochloraz induced CYP1A1 and CYP1B1 expression in both tissues. The aryl hydrocarbon receptor was also present in WAT. In contrast, neither phenobarbital nor rifampicin treatment induced CYP2 or CYP3 mRNA in WAT, and constitutive androstane receptor and pregnane X receptor were almost undetectable. These results suggest that the mechanisms by which P450s of family 1 are regulated in the liver are also functional in human WAT, but those regulating CYP2 and CYP3 expression are not.

The correlation between lipid peroxidation in different brain regions and the severity of lindane-induced seizures in rats

The aim of this study was to investigate the dynamics of lipid peroxidation and the possible correlation between lipid peroxidation in different brain regions and behavioral manifestations in lindane-induced seizures in rats. Male Wistar rats were divided into the following groups: 1. control, saline-treated group; 2. dimethylsulfoxide (DMSO)-treated group; 3. lindane-treated group (8 mg/kg), intraperitoneally. Animals were sacrificed 0.5 or 4 h after treatment and the malondialdehyde level and superoxide dismutase (SOD) activity were determined in various brain regions spectrophotometrically. Behavioral changes were classified according to the descriptive scale (0--no response, 1--head nodding, lower jaw twitching; 2--myoclonic body jerks, bilateral forelimb clonus with full rearing; 3--progression to generalized clonic convulsions followed by tonic extension of fore- and hind limbs and tail; 4--status epilepticus). A significant rise in the malondialdehyde level was detected in the cerebral cortex, hippocampus, and thalamus of lindane-treated animals 0.5 and 4 h after administration (P < 0.05). SOD activity (total and mitochondrial) was significantly decreased in the hippocampus and the cortex of lindane-treated animals at both time points (P < 0.05). An initial fall in SOD activity was detected in the thalamus 4 h after lindane administration (P < 0.05). A positive correlation between seizure severity and the malondialdehyde level was found in the hippocampus at both time points (P < 0.01). These results suggest that lipid peroxidation may contribute to the neurotoxic effects of lindane in early acute lindane intoxication and that behavioral manifestations correlate with lipid peroxidation in the hippocampus of lindane-treated rats.

Correlation between electrocorticographic and motor phenomena in lindane-induced experimental epilepsy in rats

We report a study on the relation between open-field behavior and electroencephalographic (EEG) changes during lindane-induced seizures in 2-month-old adult male Wistar rats. For chronic EEG recordings and power spectra analysis, 3 electrodes were implanted into the skull. Three groups of animals, (i) saline-injected control (n = 6), (ii) DMSO-treated (n = 6), and (iii) lindane intraperitoneally administered: L(4) (4 mg/kg, n = 10), L(6) (6 mg/kg, n = 11), and L(8) (8 mg/kg, n = 11), were observed for 30 min for the occurrence of convulsive behavior. It was assessed by incidence of motor seizures, and seizure severity grade was determined by a descriptive rating scale (0, no response; 1, head nodding, lower jaw twitching; 2, myoclonic body jerks, bilateral forelimb clonus with full rearing; 3, progression to generalized clonic convulsions followed by tonic extension of fore and hind limbs and tail; 4, status epilepticus). EEG signal and spectral analyses were suitable to describe the dynamics of complex behavioral responses. Incidence and severity of epileptic manifestations, recorded as high voltage spike-wave complexes, polyspikes, sleep-like patterns in EEG, and power spectra changes, were greater in lindane-treated groups in a dose-dependent manner compared with control or DMSO-treated groups. Our results suggest good correlation between lindane-induced epileptiform activity and behavioral changes.

Dose-dependent anticonvulsive effect of ethanol on lindane-induced seizures in rats

Chronic ethanol consumption is a major risk factor for epilepsy, and seizures frequently occur during the withdrawal period. The aim of our study was to investigate effects of ethanol on lindane-induced seizures in rats. Male Wistar rats were injected i.p. with one of the following 5 treatments: (i) saline, (ii) dimethylsulfoxide, (iii) lindane (8 mg/kg) (L), (iv) ethanol in doses of 0.5 g/kg (E(0.5)), 1 g/kg (E(1)), and 2 g/kg (E(2)), and (v) groups that received ethanol 30 min before lindane (LE(0.5), LE(1), and LE(2)). Behavioral changes were described by using a descriptive scale as follows: 0, no response; 1, head nodding, lower jaw twitching; 2, myoclonic body jerks, bilateral forelimb clonus; 3, generalized tonic-clonic convulsions; 4, status epilepticus. The incidence of convulsions in the LE(2) group was significantly lower than the incidence in the L (p < 0.01) and LE(0.5) groups (p < 0.05). The median grade of convulsive behavior was significantly lower in the LE(2) (p < 0.01) and LE(1) groups (p < 0.05) compared with the L group. Latencies to the first seizure response were not significantly different among groups. ED50 of ethanol was 1.40 (1.19-1.65). Our findings suggest that ethanol decreased severity and incidence of lindane-induced seizures in a dose-dependent manner.

Responsiveness of cerebral and hepatic cytochrome P450s in rat offspring prenatally exposed to lindane

Prenatal exposure to low doses of lindane has been shown to affect the ontogeny of xenobiotic metabolizing cytochrome P450s (CYPs), involved in the metabolism and neurobehavioral toxicity of lindane. Attempts were made in the present study to investigate the responsiveness of CYPs in offspring prenatally exposed to lindane (0.25 mg/kg b. wt.; 1/350th of LD(50); p. o. to mother) when challenged with 3-methylcholanthrene (MC) or phenobarbital (PB), inducers of CYP1A and 2B families or a sub-convulsant dose of lindane (30 mg/kg b. wt., p. o.) later in life. Prenatal exposure to lindane was found to produce an increase in the mRNA and protein expression of CYP1A1, 1A2, 2B1, 2B2 isoforms in brain and liver of the offspring at postnatal day 50. The increased expression of the CYPs in the offspring suggests the sensitivity of the CYPs during postnatal development, possibly, to low levels of lindane, which may partition into mother's milk. A higher increase in expression of CYP1A and 2B isoenzymes and their catalytic activity was observed in animals pretreated prenatally with lindane and challenged with MC (30 mg/kg, i. p. x 5 days) or PB (80 mg/kg, i. p. x 5 days) when young at age (approx. 7 weeks) compared to animals exposed to MC or PB alone. Further, challenge of the control and prenatally exposed offspring with a single sub-convulsant dose of lindane resulted in an earlier onset and increased incidence of convulsions in the offspring prenatally exposed to lindane have demonstrated sensitivity of the CYPs in the prenatally exposed offspring. Our data assume significance as the subtle changes in the expression profiles of hepatic and cerebral CYPs in rat offspring during postnatal development could modify the adult response to a later exposure to xenobiotics.

Effect of acute lindane and alcohol intoxication on serum concentration of enzymes and fatty acids in rats

This study examines possible synergistic effects of lindane and ethanol on inducing liver injury and serum fatty acid derangement in adult male Wistar rats. When administered together, ethanol and lindane-induced even more pronounced increase of alanine aminotransferase (165 +/- 10 U/L) and gamma-glutamyltranspeptidase activity (10.3 +/- 0.6 U/L) than after isolated administration of either substance. In addition, separate administration of lindane and ethanol was followed by a significant decrease of linoleic acid level in the serum (301 +/- 38 mg/L, 276 +/- 35 mg/L vs. 416 +/- 48 mg/L). However, when ethanol administration was followed by lindane injection, serum linoleic acid was at the similar level found in the control group (516 +/- 62 mg/L). Ethanol-treated rats that received lindane 30 min after ethanol administration have shown a marked increase of palmitic (421 +/- 27 mg/L) and linolic acid level (43 +/- 5 mg/L) in comparison with rats that have been treated only with ethanol (316+/-26 mg/L for palmitic and 32 +/- 2 mg/L for linolic acid) or lindane (295 +/- 26 mg/L for palmitic and 301 +/- 38 mg/L for linolic acid). Linolic acid level was significantly greater in comparison with control group (29 +/- 1 mg/L). In conclusion, this study found enough evidence to support the hypothesis that acute ethanol intoxication potentiates lindane-induced liver injury and enhances lipid derangement.

Reversal of lindane-induced impairment of step-down passive avoidance and oxidative stress by neurosteroids in rats

Neurosteroids (NS) are recognized as important modulators of functioning of the nervous system. Lindane, an organochlorine pesticide has been shown to adversely affect memory and induce oxidative stress on both acute and chronic exposure. The present study was designed to explore the modulation of effects of lindane over cognitive function by progesterone (PROG), pregnenolone sulfate (PREG-S) and 4'-chlorodiazepam (4CD). Cognitive function was assessed using step-down latency (SDL) on a passive avoidance apparatus and transfer latency (TL) on a plus maze. Oxidative stress was assessed by examining brain malondialdehyde (MDA) and non-protein thiol (NP-SH) levels. A significant reduction in SDL was found for the lindane treated group at weeks 6 and 7 as compared to control (p<0.001). One-week treatment by PREG-S or 4CD antagonized the effect of lindane on SDL. PROG failed to modulate the effect of lindane on SDL. Lindane caused a significant prolongation of TL as compared to control (p<0.001) from second week onwards. One-week administration of PROG, PREG-S or 4CD was unable to reverse this prolongation of TL. Lindane produced a statistically significant increase in the brain MDA levels (p<0.001) and significant decrease in the brain NP-SH levels (p<0.001). Treatment with PREG-S and 4CD attenuated the effect of lindane on MDA (p<0.001) and NP-SH levels. PROG failed to influence oxidative stress induced by lindane. Results of the present study thus show that some NS have potential in reversing cognitive dysfunction and oxidative stress induced by toxicants like lindane in the brain.

Workgroup report: incorporating in vitro alternative methods for developmental neurotoxicity into international hazard and risk assessment strategies

This is the report of the first workshop on Incorporating In Vitro Alternative Methods for Developmental Neurotoxicity (DNT) Testing into International Hazard and Risk Assessment Strategies, held in Ispra, Italy, on 19-21 April 2005. The workshop was hosted by the European Centre for the Validation of Alternative Methods (ECVAM) and jointly organized by ECVAM, the European Chemical Industry Council, and the Johns Hopkins University Center for Alternatives to Animal Testing. The primary aim of the workshop was to identify and catalog potential methods that could be used to assess how data from in vitro alternative methods could help to predict and identify DNT hazards. Working groups focused on two different aspects: a) details on the science available in the field of DNT, including discussions on the models available to capture the critical DNT mechanisms and processes, and b) policy and strategy aspects to assess the integration of alternative methods in a regulatory framework. This report summarizes these discussions and details the recommendations and priorities for future work.

Quantitative trait transcripts for nicotine resistance in Drosophila melanogaster

Although most genetic association studies are performed with the intention of detecting nucleotide polymorphisms that are correlated with a complex trait, transcript abundance should also be expected to associate with diseases or phenotypes. We performed a scan for such quantitative trait transcripts in adult female heads of the fruit fly (Drosophila melanogaster) that might explain variation for nicotine resistance. The strongest association was seen for abundance of ornithine aminotransferase transcripts, implicating detoxification and neurotransmitter biosynthesis as mediators of the quantitative response to the drug. Subsequently, genetic analysis and metabolite profiling confirmed a complex role for ornithine and GABA levels in modification of survival time upon chronic nicotine exposure. Differences between populations from North Carolina and California suggest that the resistance mechanism may be an evolved response to environmental exposure.

Multiscale approach of fish responses to different types of environmental contaminations: a case study

In order to study the responses of wild fish to environmental contaminations, different sites (two references and three contaminated) were sampled across the Walloon hydrographical network (southern Belgium). The status of fish communities was characterized according to an index of biotic integrity (IBI). Furthermore, population structure, reproductive parameters and biochemical assays were performed on chub (Leuciscus cephalus) as sentinel species. The results showed impaired responses in fish sampled downstream paper mill effluents (BKME), in a polychlorinated biphenyls (PCB) contaminated site, and in a river receiving pesticides (i.e. atrazine and hexachlorocyclohexane). High level of hepatic 7-ethoxyresorufin-Odeethylase (EROD) activity were evidence of direct toxicant exposure, while population structures showed unbalanced size-frequency distributions. Moreover, in the pesticide contaminated site, a higher proportion of atretic oocytes was found in females and abnormally high plasma alkali-labile phosphorus (ALP) values were noticed in males, compared to reference sites, suggesting that chubs were exposed to estrogenic compounds. IBI scores from both sites were also lower than in reference sites. On the other hand, no particular response was found in hepatic glutathione-S-transferase (GST) activities, hepatic heat-shock protein HSP70 concentrations and plasma sex steroids (estradiol-17beta, 11-ketotestosterone and testosterone) in chubs from any sites. By using a multiparametric approach, a better understanding of response mechanisms to pollution in fish may be achieved in order to improve the ecological status of river ecosystems.

Induction of oxidative stress by lindane in epididymis of adult male rats

Lindane, an organochlorine pesticide, has been reported to induce reproductive abnormalities in male rats. The mechanism of action of lindane on male reproductive system remains unclear. In the present study we have sought to investigate the effect of lindane on antioxidant parameters and sialic acid levels of caput, corpus and cauda epididymis of adult male rats. Lindane (1, 5, and 50mg/kg per day) was administered orally to adult male rats for 45 days. The animals were killed using anaesthic ether on the day following the last treatment. The body weight of the animals did not show significant change. However, the weights of caput, corpus and cauda epididymis decreased in lindane treated animals. Administration of lindane caused decrease in epididymal sperm count and motility. Sialic acid levels in the epididymis decreased significantly at 5 and 50mg/kg dosage of lindane treatment. Significant decline in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase along with increase in hydrogen peroxide generation and lipid peroxidation were observed in lindane treated animals. In conclusion, lindane induces oxidative stress by decreasing the activities of antioxidant enzymes and sialic acid levels in the epididymis thereby causing impaired sperm function.