Effect of 17ß-estradiol on striatal dopaminergic transmission induced by permethrin in early childhood rats.

A positive effect of estrogen treatment has been observed in neurodegenerative diseases such as Parkinson's disease. Since 17ß-estradiol can modulate positively dopaminergic system, here we sought to evaluate the effect of 17ß-estradiol supplementation on an animal model developing dopaminergic alterations on nucleus of striatum after neonatal exposure to permethrin pesticide. The goal of the study was to verify if the co-treatment with 17ß-estradiol could protect against the damage induced by pesticide exposure in early life. Permethrin treated rats showed a decrease of dopamine and Nurr1 gene expression in striatum, while a more pronounced decrease of dopamine was observed in rats co-administered with permethrin+17ß-estradiol. No difference between control and permethrin treated rats was observed in both mRNA of ERα and ERß, whereas the rats co-administered with permethrin+17ß-estradiol showed a down-regulation of ERα expression. The in vitro studies showed that permethrin, at high concentration may have an antagonist effect on ERα and even more pronounced in ERß, thus suggesting that permethrin may block the estrogen neuroprotective effects. In conclusion, in male rats, the administration of estrogen further enhanced the impairment of dopaminergic transmission due to exposure to permethrin.

Neonatal exposure to permethrin pesticide causes lifelong fear and spatial learning deficits and alters hippocampal morphology of synapses.

BACKGROUND: During the neurodevelopmental period, the brain is potentially more susceptible to environmental exposure to pollutants. The aim was to determine if neonatal exposure to permethrin (PERM) pesticide, at a low dosage that does not produce signs of obvious abnormalities, could represent a risk for the onset of diseases later in the life. METHODS: Neonatal rats (from postnatal day 6 to 21) were treated daily by gavage with a dose of PERM (34 mg/kg) close to the no-observed-adverse-effect level (NOAEL), and hippocampal morphology and function of synapses were investigated in adulthood. Fear conditioning, passive avoidance and Morris water maze tests were used to assess cognitive skills in rats, whereas electron microscopy analysis was used to investigate hippocampal morphological changes that occurred in adults. RESULTS: In both contextual and tone fear conditioning tests, PERM-treated rats showed a decreased freezing. In the passive avoidance test, the consolidation of the inhibitory avoidance was time-limited: the memory was not impaired for the first 24 h, whereas the information was not retained 72 h following training. The same trend was observed in the spatial reference memories acquired by Morris water maze. In PERM-treated rats, electron microscopy analysis revealed a decrease of synapses and surface densities in the stratum moleculare of CA1, in the inner molecular layer of the dentate gyrus and in the mossy fibers of the hippocampal areas together with a decrease of perforated synapses in the stratum moleculare of CA1 and in the inner molecular layer of the dentate gyrus. CONCLUSIONS: Early-life permethrin exposure imparts long-lasting consequences on the hippocampus such as impairment of long-term memory storage and synaptic morphology.

Early life permethrin treatment leads to long-term cardiotoxicity.

Environmental, nutritional or hormonal influences in early life may have long-term effects changing homeostatic processes and physiological parameters in adulthood. NF-kB and Nrf2, two of the main transcription factors regulating genes involved in pro-inflammatory and antioxidant responses respectively, can be modified by various stimuli. NF-kB controls immediate early genes and is required for cardiomyocyte hypertrophic growth, while Nrf2 protects the heart from oxidative stress-induced cardiovascular complications. The aim of this study was to investigate the impact of early life permethrin treatment (1/50 of LD50, from 6th to 21st day of life) on the development of cardiotoxicity in 500-day-old rats. Nrf2 and NF-kB gene expression, calcium level and heart surface area were chosen as biomarkers of toxicity. Six candidate reference genes were first examined and GAPDH resulted the most stable one for RT-qPCR. The comparative expression analysis of the target genes showed 1.62-fold increase in Nrf2 mRNA level, while the NF-kB mRNA in treated rats was not significantly changed compared to control ones. A significant decrease in heart surface area was observed in treated rats (296.59 ± 8.09, mm(2)) with respect to the control group (320.86 ± 4.93, mm(2)). Finally, the intracellular calcium influx in heart of early life treated rats increased 4.33-fold compared to the control one. In conclusion, early life pesticide exposure to low doses of permethrin insecticide, has long-term consequences leading to cardiac hypotrophy, increased calcium and Nrf2 gene expression levels in old age.

Exercise-induced heart mitochondrial cholesterol depletion influences the inhibition of mitochondrial swelling.

The significance of the reduction of the cholesterol pool in heart mitochondria after exercise is still unknown. Recently, published data have suggested that cholesterol may influence the components of mitochondrial contact site and affect mitochondrial swelling. Therefore, the aim of this study was to determine whether the decreased cholesterol content in heart mitochondria caused by prolonged swimming may provoke changes in their bioenergetics and result in an increased resistance to calcium chloride-induced mitochondrial swelling. Male Wistar rats were divided into a sedentary control group and an exercise group. The rats exercised for 3 h, burdened with an additional 3% of their body weight. Their hearts were removed immediately after completing the exercise. The left ventricle was divided and used for experiments. Mitochondrial cholesterol content, membrane fluidity and mitochondrial bioenergetics were measured in the control and exercised rat heart mitochondria. To assess whether mitochondrial modifications are linked to disruption of lipid microdomains, methyl-ß-cyclodextrin, a well-known lipid microdomain-disrupting agent and cholesterol chelator, was applied to the mitochondria of the control group. Cholesterol depletion, increased membrane fluidity and increased resistance to calcium chloride-induced swelling were observed in postexercise heart crude mitochondrial fraction. Similar results were achieved in control mitochondria treated with 2% methyl-ß-cyclodextrin. All of the mitochondrial bioenergetics parameters were similar between the groups. Therefore, the disruption of raft-like microdomains appears to be an adaptive change in the rat heart following exercise.

Early life permethrin exposure induces long-term brain changes in Nurr1, NF-kB and Nrf-2.

Pesticide exposure during brain development represents an important risk factor for the onset of brain-aging processes. Here, the impact of permethrin administered to rats from 6th to 21st day of life, at a dose near to "no observed adverse effect level" (NOAEL), was studied when animals reached 500 day-old. The permethrin treatment induced a decrease in Nurr1 gene expression in striatum, an increase in hippocampus and cerebellum, while the protein level changed only in striatum where it was increased. NF-kB p65 gene expression was increased in cerebellum, while its protein level augmented in cerebellum and in prefrontal cortex and decreased in hippocampus of treated rats compared to control ones. Nrf-2 gene expression resulted significantly higher only in cerebellum of treated animals. The results suggest that early life permethrin treatment induces long-lasting effects leading to dopaminergic neuronal disorders, monitored by Nurr1 alteration. Moreover the impairment of NF-kB and Nrf-2, important for the balance between pro- and anti-inflammatory systems, confirms that the neonatal permethrin treatment can influence genes involved with the onset of brain-ageing processes.

Effects of early life permethrin exposure on spatial working memory and on monoamine levels in different brain areas of pre-senescent rats.

Pesticide exposure during brain development could represent an important risk factor for the onset of neurodegenerative diseases. Previous studies investigated the effect of permethrin (PERM) administered at 34 mg/kg, a dose close to the no observable adverse effect level (NOAEL) from post natal day (PND) 6 to PND 21 in rats. Despite the PERM dose did not elicited overt signs of toxicity (i.e. normal body weight gain curve), it was able to induce striatal neurodegeneration (dopamine and Nurr1 reduction, and lipid peroxidation increase). The present study was designed to characterize the cognitive deficits in the current animal model. When during late adulthood PERM treated rats were tested for spatial working memory performances in a T-maze-rewarded alternation task they took longer to choose for the correct arm in comparison to age matched controls. No differences between groups were found in anxiety-like state, locomotor activity, feeding behavior and spatial orientation task. Our findings showing a selective effect of PERM treatment on the T-maze task point to an involvement of frontal cortico-striatal circuitry rather than to a role for the hippocampus. The predominant disturbances concern the dopamine (DA) depletion in the striatum and, the serotonin (5-HT) and noradrenaline (NE) unbalance together with a hypometabolic state in the medial prefrontal cortex area. In the hippocampus, an increase of NE and a decrease of DA were observed in PERM treated rats as compared to controls. The concentration of the most representative marker for pyrethroid exposure (3-phenoxybenzoic acid) measured in the urine of rodents 12 h after the last treatment was 41.50 µg/L and it was completely eliminated after 96 h.

Early life permethrin exposure leads to hypervitaminosis D, nitric oxide and catecholamines impairment.

The aim of this study is to gain more knowledge on the impact of early life pesticide exposure on premature aging. The effect of a low dose of the insecticide permethrin administered to rats during early life (1/50 LD50, from 6th to 21st day of life) was analyzed by measuring some metabolites in plasma and urine of 500-day-old animals. Significant differences in early life treated rats compared to the control group were found in the plasma levels of Ca(++), Na(+), 25-hydroxy-vitamin D, adrenaline, noradrenaline, nitric oxide, cholesterol and urea while in urine only Na(+) content was different. These results add information on the impact of permethrin during the neonatal period, supporting the evidence that early life environmental exposure to xenobiotics has long-term effects, inducing modifications in adulthood that can be revealed by the analysis of some macroelements, metabolites and catecholamines in plasma, when rats are 500 days old.

Leukocyte Nurr1 as peripheral biomarker of early-life environmental exposure to permethrin insecticide.

The effect of a low dose of the insecticide permethrin administered during early-life was evaluated on leukocytes inflammation mediators on 300- and 500-day-old rats. Nurr1, NF-κB-p65, Nrf2, lipid peroxidation and GSH levels increased with age but compared to the control group, treatment with permethrin induced a significant increase only of Nurr1 and lipid peroxidation in oldest rats. TNF-α and Rantes increased, while IL-1ß, IL-2, IL-13 decreased in oldest treated rats. The results propose Nurr1, TNF-α, Rantes, GSH and plasma lipid peroxidation as peripheral biomarkers for monitoring the impact of early-life environmental exposure to xenobiotics in old age.

The impact of early life permethrin exposure on development of neurodegeneration in adulthood.

Early life environmental exposure to pesticides could play a critical role in the onset of age-related diseases. The present study aims to evaluate in brain, plasma and leukocytes of 300 day-old rats, the effect of a low dose of the insecticide permethrin administered during early life (1/50 LD(50), from 6th to 21st day of life). The outcomes show that Nurr1, mRNA and protein expression, as well as calcium and NO levels are decreased in striatum. Moreover, the pesticide induces an imbalance in glutamate, calcium and NO in hippocampus. Low calcium concentrations in leukocytes and in plasma were observed, while increased NO and decreased SOD plasma levels were measured. The results suggest that permethrin intake at a dose close to the NOAEL (25 mg/kg) during the perinatal period can interact with Nurr1 by reducing its expression on striatum nucleus. Consequently, the maintenance of dopaminergic neurons as well as Nurr1 inhibitory effect on the production of proinflammatory mediators fails. The changes in biological markers found in our animal model could represent the basis to study neurodegenerative diseases whose development depends on individual gene signature and life style.

Early life permethrin insecticide treatment leads to heart damage in adult rats.

Early life environmental exposure to xenobiotics could represent a critical period for the onset of permanent alterations in the structure and function of different organs. Cardiovascular diseases can be related to various factors including environmental toxicants. The aim of the present study was to evaluate the effect of early life permethrin treatment (1/50 LD(50), from 6th to 21st day of life) on heart of adult rats. Increased DNA damage, decreased heart cell membrane fluidity, increased cholesterol content, protein and lipid oxidation were measured in heart cells from adult rats treated with permethrin during the neonatal period with respect to control rats. Moreover, the same group showed higher levels of cholesterol, IL-1ß, IL-2, IFN-γ, rat-Rantes and IL-10 cytokines and decreased albumin content in plasma. Lower cholesterol levels and perturbation in the phospholipid lateral diffusion together with decreased GSH levels and increased GPx activity were measured in heart mitochondria of the treated group. Our findings support the evidence that the neonatal period has a critical role in the development of heart disease in adulthood. We hypothesize that the alterations observed in adult rats could depend on epigenetic changes that occurred during this period which influence gene expression throughout the rat's life, leading to alterations of certain parameters related to cardiac function.

Perturbation of rat heart plasma membrane fluidity due to metabolites of permethrin insecticide.

Due to increased global use, acute and chronic exposures to pyrethroid insecticides in humans are of clinical concern. Pyrethroids have a primary mode of action that involves interference with the sodium and calcium channels in excitable cells, which may include cardiac myocytes. Here, we investigated the possible cardiac toxicity of permethrin metabolites (METP), 3-phenoxy-benzyl alcohol (3PBA), 3-phenoxy-benzaldehyde (3PBALD), and 3-phenoxybenzoic acid (3PBACID). Plasma membrane fluidity, polarity, lipid, and protein oxidation were studied in isolated rat heart cells. Laurdan was chosen as probe to detect the lateral mobility and polarity of its environment and thus water penetration into the hydrophobic part of the bilayer, while 1,6-diphenyl-1,3,5-hexatriene permits to measure changes in fluidity in the inner part of the bilayer. Results show that METP can change membrane fluidity at different depths of the bilayer according to their partition coefficient. Consequently, 3PBA, at all concentration used, decreases membrane fluidity and polarity in the hydrophilic-hydrophobic region of the bilayer, and similar effect was observed with 20 µM 3PBALD or 10 or 20 µM 3 PBACID. Membrane dynamics in the hydrophobic core resulted decreased by 3PBALD, while it was increased by 20 µM 3PBACID. All METP increase protein and lipid oxidation, and the peroxidative lipid damage decreases with the type of METP produced during the transformation pathway from parent compound to 3PBACID. Consequently, 3PBA induced the highest lipid peroxidation, while 3PBACID was the stronger inducer of protein damage.

Oxidative damage in trout erythrocyte in response to "in vitro" copper exposure.

The oxidative action of copper on different trout Oncorhynchus mykiss erythrocyte components was studied. The results indicate that: --cupric ions differently influence the oxidative status of two trout hemoglobin components I and IV (HbI and HbIV) having different structural and functional properties; --reactive oxygen species (ROS) production associated with hemoglobins autoxidation is not influenced by the presence of copper sulfate; --the susceptibility to hemolysis increases in the presence of copper only when the erythrocyte suspension is incubated in air; the effect of copper is almost absent for carbon monoxide-saturated erythrocyte suspensions; --DNA damage due to copper was not observed in our experimental conditions. The data obtained are important for the analysis of the environmental risks produced by copper on fish.