The 28-day exposure to fenpropathrin decreases locomotor activity and reduces activity of antioxidant enzymes in mice brains

Neurotoxicity of Pyrethroids in neurodegenerative diseases: From animals' models to humans' studies

Neurodegenerative diseases are associated with diverse symptoms, both motor and mental. Genetic and environmental factors can trigger neurodegenerative diseases. Chemicals as pesticides are constantly used in agriculture and also domestically. In this regard, pyrethroids (PY), are a class of insecticides in which its main mechanism of action is through disruption of voltage-dependent sodium channels function in insects. However, in mammals, they can also induce oxidative stress and enzyme dysfunction. This review investigates the association between PY and neurodegenerative diseases as Alzheimer's, Huntington's, Parkinson's, Amyotrophic Lateral Sclerosis, and Autism in animal models and humans. Published works using specific and non-specific models for these diseases were selected. We showed a tendency toward the development and/or aggravating of these neurodegenerative diseases following exposure to PYs. In animal models, the biochemical mechanisms of the diseases and their interaction with the insecticides are more deeply investigated. Nonetheless, only a few studies considered the specific model for each type of disease to analyze the impacts of the exposure. The choice of a specific model during the research is an important step and our review highlights the knowledge gaps of PYs effects using these models reinforcing the importance of them during the design of the experiments.

Fenpropathrin causes alterations in locomotion and social behaviors in zebrafish (Danio rerio)

Fenpropathrin is one of the widely used pyrethroid pesticides in agriculture and is frequently detected in the environment, groundwater, and food. While fenpropathrin was found to have neurotoxic effects in mammals, it remains unclear whether it has similar effects on fish. Here, we used adult zebrafish to investigate the impacts of fenpropathrin on fish social behaviors and neural activity. Exposure of adult zebrafish to 500 ppb of fenpropathrin for 72 h increased anxiety levels but decreased physical fitness, as measured by a novel tank diving test and swimming tunnel test. Fish exposed to fenpropathrin appeared to spend more time in the conspecific zone of the tank, possibly seeking greater comfort from their companions. Although learning, memory, and aggressive behavior did not change, fish exposed to fenpropathrin appeared to have shorter fighting durations. The immunocytochemical results showed the tyrosine hydroxylase antibody-labeled dopaminergic neurons in the teleost posterior tuberculum decreased in the zebrafish brain. According to a quantitative polymerase chain reaction (qPCR) analysis of the brain, exposure to fenpropathrin resulted in a decrease in the messenger (m)RNA expression of monoamine oxidase (mao), an enzyme that facilitates the deamination of dopamine. In contrast, the mRNA expression of the sncga gene, which may trigger Parkinson's disease, was found to have increased. There were no changes observed in expressions of genes related to antioxidants and apoptosis between the control and fenpropathrin-exposed groups. We provide evidence to demonstrate the defect of the neurotoxicity of fenpropathrin toward dopaminergic neurons in adult zebrafish.

The Effect of the Pyrethroid Pesticide Fenpropathrin on the Cardiac Performance of Zebrafish and the Potential Mechanism of Toxicity

Fenpropathrin, a pyrethroid insecticide, has been widely used for many years in agricultural fields. It works by disturbing the voltage-gated sodium channel, leading to paralysis and the death of the target animal. While past studies have focused on neurodegeneration following fenpropathrin poisoning in humans, relatively few pieces of research have examined its effect on other peripheral organs. This study successfully investigated the potential toxicity of fenpropathrin on the cardiovascular system using zebrafish as an animal model. Zebrafish larvae exposed to varying doses of fenpropathrin underwent an evaluation of cardiac physiology by measuring the heart rate, stroke volume, cardiac output, and shortening fraction. The blood flow velocity and the dorsal aorta diameter were also measured to assess the impact of fenpropathrin exposure on the vascular system. Furthermore, molecular docking was performed to evaluate the pesticide binding affinity to various proteins associated with the cardiovascular system, revealing the potential mechanism of the fenpropathrin cardiotoxic effect. The findings demonstrated a significant dose-dependent increase in the heart rate stroke volume, cardiac output, shortening fraction, and ejection fraction of zebrafish larvae after 24 h of acute treatment with fenpropathrin. Additionally, zebrafish treated at a concentration of 1 ppm exhibited significantly larger blood vessels in diameter and an increased blood flow velocity compared to the control group. According to molecular docking, fenpropathrin showed a high affinity for various voltage-gated sodium channels like scn1lab, cacna1sb, and clcn3. Finally, from the results, we found that fenpropathrin caused cardiomegaly, which may have been induced by the voltage-gated sodium channel disruption. This study highlights the significant disruption of fenpropathrin in the cardiovascular system and emphasizes the need for further research on the health implications of this pesticide.

Risk Factors for Brain Health in Agricultural Work: A Systematic Review

Certain exposures related to agricultural work have been associated with neurological disorders. To date, few studies have included brain health measurements to link specific risk factors with possible neural mechanisms. Moreover, a synthesis of agricultural risk factors associated with poorer brain health outcomes is missing. In this systematic review, we identified 106 articles using keywords related to agriculture, occupational exposure, and the brain. We identified seven major risk factors: non-specific factors that are associated with agricultural work itself, toluene, pesticides, heavy metal or dust exposure, work with farm animals, and nicotine exposure from plants. Of these, pesticides are the most highly studied. The majority of qualifying studies were epidemiological studies. Nigral striatal regions were the most well studied brain area impacted. Of the three human neuroimaging studies we found, two focused on functional networks and the third focused on gray matter. We identified two major directions for future studies that will help inform preventative strategies for brain health in vulnerable agricultural workers: (1) the effects of moderators such as type of work, sex, migrant status, race, and age; and (2) more comprehensive brain imaging studies, both observational and experimental, involving several imaging techniques.

Asparagine endopeptidase inhibitor protects against fenpropathrin-induced neurodegeneration via suppressing α-synuclein aggregation and neuroinflammation

Exposure to fenpropathrin (Fen), one of the most widely used pyrethroid pesticides, has been reported to increase the incidence of Parkinson's disease (PD). However, the molecular mechanisms underlying Fen-induced Parkinsonism remain unknown. Here we investigated the role of the lysosomal protease asparagine endopeptidase (AEP) in Fen-induced neurodegeneration and tested the protective effect of an AEP inhibitor Compound #11 (CP11). Fen induced AEP activation, α-synuclein aggregation, and dopaminergic neuronal degeneration both in vitro and in vivo. CP11 alleviated Fen-induced cell injury in cultured SH-SY5Y cells and A53T α-synuclein transgenic mice. CP11 protected SH-SY5Y cells against Fen-induced toxicity and decreased α-synuclein aggregation in HEK293 cells stably transfected with α-synuclein. In Fen-treated mice, CP11 attenuated the degeneration of dopaminergic neurons and reduced neuroinflammation. Our findings demonstrate that neurodegeneration in Fen-treated models might be attributed to the activation of AEP. AEP might be a novel therapeutic target in PD induced by Fen and other environmental factors.

Fenpropathrin induces degeneration of dopaminergic neurons via disruption of the mitochondrial quality control system

The synthetic pyrethroid derivative, fenpropathrin, is a widely used insecticide. However, a variety of toxic effects in mammals have been reported. In particular, fenpropathrin induces degeneration of dopaminergic neurons and parkinsonism. However, the mechanism of fenpropathrin-induced parkinsonism has remained unknown. In the present study, we investigated the toxic effects and underlying mechanisms of fenpropathrin on perturbing the dopaminergic system both in vivo and in vitro. We found that fenpropathrin induced cellular death of dopaminergic neurons in vivo. Furthermore, fenpropathrin increased the generation of reactive oxygen species, disrupted both mitochondrial function and dynamic networks, impaired synaptic communication, and promoted mitophagy in vitro. In mice, fenpropathrin was administered into the striatum via stereotaxic (ST) injections. ST-injected mice exhibited poor locomotor function at 24 weeks after the first ST injection and the number of tyrosine hydroxylase (TH)-positive cells and level of TH protein in the substantia nigra pars compacta were significantly decreased, as compared to these parameters in vehicle-treated mice. Taken together, our results demonstrate that exposure to fenpropathrin induces a loss of dopaminergic neurons and partially mimics the pathologic features of Parkinson's disease. These findings suggest that fenpropathrin may induce neuronal degeneration via dysregulation of mitochondrial function and the mitochondrial quality control system.

Ovarian Index of KM Mice Influenced by Longer Term Consumption of Microwave-Heated Milk

ABSTRACT

Microwave technology has been widely used in the food industry, but the effect of microwave-heated food on human health is being questioned. Female KM mice were chosen to be treated with microwave-heated milk (MM), and reproductive markers such as litter size, birth rate, survival rate, and ovarian index were evaluated. With longer term feeding, the reproductive status (body weight, birth rate, litter size, neonatal survival rate, interpregnancy interval, and brain superoxide dismutase and catalase activity) of KM mice treated with MM did not significantly change except for the ovarian index of first-generation mice, which was decreased significantly compared with the control group and the group given electrically heated milk. Longer term consumption of MM can affect the ovarian index of reproductive mice.

HIGHLIGHTS

The effect of subacute poisoning with fenpropathrin on mice kidney function and the level of interleukin 1β and tumor necrosis factor α

Fenpropathrin (FEN) is a pyrethroid insecticide. Mammals can be exposed to these compounds with food and water as non-target organisms. Pyrethroids are classified into two types depending on chemical structure and neurotoxic effects. FEN has features of Type I and Type II pyrethroids. There is data that pyrethroids apart from neurotoxic properties, can be also nephrotoxic and immunotoxic. The aim of the study was to assess the influence of FEN on kidney function and concentration of proinflammatory cytokines: tumor necrosis factor alpha (TNFα) and interleukin 1 beta (IL-1β) in mice kidneys. Sixteen female mice were randomly divided into two groups: I—receiving saline and II—receiving FEN at the dose of 11.9 mg/kg ip for 28 consecutive days. On day 29 blood samples were obtained to measure serum creatinine concentration. The animals were killed, and kidneys were obtained in order to measure TNFα and interleukin IL-1β in mice kidneys with use of ELISA assay. The concentration of creatinine was (mean ± SD) in controls 0.2 ± 0.0 mg/dl in the group exposed to FEN 0.225 ± 0.046 mg/dl. TNFα concentration in the kidneys of controls was 6.154 ± 1.597 pg/ml and in the group intoxicated with FEN it was 6.318 ± 1.012 pg/ml. IL-1β concentration in the kidneys of controls was 4.67 ± 1.154 pg/ml while in the group intoxicated with FEN 27.983 ± 26.382 pg/ml (p < 0.05). In conclusion: FEN slightly affects kidney function and increases the concentration of proinflammatory IL-1β in mice kidneys, which supports the hypothesis about nephrotoxic and immunotoxic effect of this insecticide in non target organisms.

Gene Dysfunction Mediates Immune Response to Dopaminergic Degeneration in Parkinson's Disease

Many publications reported that genetic dysfunction mediates abnormal immune responses in the brain, which is important for the development of neurodegenerative diseases, especially for Parkinson's disease (PD). This immune disorder results in subsequent inflammatory reaction, which stimulates microglia or other immune cells to secrete cytokines and chemokines and disturbs the proportion of peripheral blood lymphocyte subsets contributing to dopaminergic (DA) neuron apoptosis. Furthermore, the abnormal immune related signal pathways caused by genetic variants promote chronic inflammation destroying the blood-brain barrier, which allows infiltration of different molecules and blood cells into the central nervous system (CNS) exerting toxicity on DA neurons. As a result, the inflammatory reaction in the CNS accelerates the progression of Parkinson's disease and promotes α-synuclein aggregation and diffusion among DA neurons in the procession of Parkinson's disease. Thus, for disease evaluation, the genetic mediated abnormal immune response in PD may be assessed based on the multiple immune molecules and inflammatory factors, as well as the ratio of lymphocyte subsets from PD patient's peripheral blood as potential biomarkers.