Effect of mosquito mats (pyrethroid-based) vapor inhalation on rat brain cytochrome P450s

The potential impact of CYP and UGT drug-metabolizing enzymes on brain target site drug exposure

Drug metabolism is one of the critical determinants of drug disposition throughout the body. While traditionally associated with the liver, recent research has unveiled the presence and functional significance of drug-metabolizing enzymes (DMEs) within the brain. Specifically, cytochrome P-450 enzymes (CYPs) and UDP-glucuronosyltransferases (UGTs) enzymes have emerged as key players in drug biotransformation within the central nervous system (CNS). This comprehensive review explores the cellular and subcellular distribution of CYPs and UGTs within the CNS, emphasizing regional expression and contrasting profiles between the liver and brain, humans and rats. Moreover, we discuss the impact of species and sex differences on CYPs and UGTs within the CNS. This review also provides an overview of methodologies for identifying and quantifying enzyme activities in the brain. Additionally, we present factors influencing CYPs and UGTs activities in the brain, including genetic polymorphisms, physiological variables, pathophysiological conditions, and environmental factors. Examples of CYP- and UGT-mediated drug metabolism within the brain are presented at the end, illustrating the pivotal role of these enzymes in drug therapy and potential toxicity. In conclusion, this review enhances our understanding of drug metabolism's significance in the brain, with a specific focus on CYPs and UGTs. Insights into the expression, activity, and influential factors of these enzymes within the CNS have crucial implications for drug development, the design of safe drug treatment strategies, and the comprehension of drug actions within the CNS. To that end, CNS pharmacokinetic (PK) models can be improved to further advance drug development and personalized therapy.

Effects of pyrethroids on the cerebellum and related mechanisms: a narrative review

Pyrethroids (PYRs) are a group of synthetic organic chemicals that mimic natural pyrethrins. Due to their low toxicity and persistence in mammals, they are widely used today. PYRs exhibit higher lipophilicity than other insecticides, which allows them to easily penetrate the blood-brain barrier and directly induce toxic effects on the central nervous system. Several studies have shown that the cerebellum appears to be one of the regions with the largest changes in biomarkers. The cerebellum, which is extremely responsive to PYRs, functions as a crucial region for storing motor learning memories. Exposure to low doses of various types of PYRs during rat development resulted in diverse long-term effects on motor activity and coordination functions. Reduced motor activity may result from developmental exposure to PYRs in rats, as indicated by delayed cerebellar morphogenesis and maturation. PYRs also caused adverse histopathological and biochemical changes in the cerebellum of mothers and their offspring. By some studies, PYRs may affect granule cells and Purkinje cells, causing damage to cerebellar structures. Destruction of cerebellar structures and morphological defects in Purkinje cells are known to be directly related to functional impairment of motor coordination. Although numerous data support that PYRs cause damage to cerebellar structures, function and development, the mechanisms are not completely understood and require further in-depth studies. This paper reviews the available evidence on the relationship between the use of PYRs and cerebellar damage and discusses the mechanisms of PYRs.

Effects of prenatal exposure to pyrethroid pesticides on neurodevelopment of 1-year- old children: A birth cohort study in China

Pregnant women have been ubiquitously exposed to pyrethroid pesticides. Previous studies, mainly based on third trimester measurements of maternal urinary pyrethroid metabolites, have reported inconsistent findings in the effects of prenatal pyrethroid exposure on children's neurodevelopmental outcomes. The purpose of this study was to clarify if pyrethroid exposure during the entire three trimesters of pregnancy may be associated with deleterious effects on infant neurodevelopmental status, particularly at a high dosage of exposure. We measured maternal urinary concentrations of pyrethroid metabolites in all trimesters of pregnancy and assessed children's neurodevelopment at one year of age using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III). Multiple linear regression models were used to estimate the effects of metabolites (3-PBA, 4 F-3-PBA, cis-DBCA) in each trimester on BSID-III composite scores. Logistic regression analyses were applied to predict developmental delay vs non-delayed status (cut-off composite score of below 80 for developmental delay) based on the maternal levels of pyrethroid metabolites. In the first, second and third trimesters of pregnancy, the detection rates of pyrethroid metabolites were 94.7%, 90.7%, and 89.0%; the 50th percentiles of exposure level were 0.24 μg/g, 0.24 μg/g and 0.21 μg/g for 3-PBA, 0.14 μg/g, 0.17 μg/g and 0.15 μg/g for 4 F-3PBA, 0.21 μg/g, 0.25 μg/g and 0.19 μg/g for cis-DBCA respectively. In the second trimester, 3-PBA was inversely associated with Cognition and Language scores [β = -3.34 (95% CI = -6.11, -0.57) and β = -2.90 (95% CI = -5.20, -0.61), respectively], and significantly increased the risk of Cognition and Language developmental delay [OR= 1.64 (95% CI = 1.03, 2.62) and OR = 1.52 (95% CI = 1.06, 2.19), respectively]; cis-DBCA was inversely associated with Adaptive Behavior scores [β = -0.73 (95% CI = -1.27, -0.19)], and significantly increased the risk of Adaptive Behavior developmental delay [OR= 1.11 (95% CI = 1.02, 1.21)]. When the maternal levels of pyrethroid metabolites were stratified into the regression models according to the 90th percentile of exposure, in the first trimester, Cognition and Motor scores were inversely associated with higher cis-DBCA [β = -7.19 (95% CI = -12.97, -1.41) and β = -8.20 (95% CI = -13.35, -3.05), respectively], Language scores were inversely associated with higher 3-PBA [β = -6.01 (95% CI = -10.96, -1.06)]; in the second trimester, Cognition scores were inversely associated with higher cis-DBCA [β = -6.64 (95% CI = -12.51, -0.76)], Language scores were inversely associated with higher 3-PBA [β = -5.17 (95% CI = -10.07, -0.27)] and cis-DBCA [β = -5.40 (95% CI = -10.28, -0.52)]. We concluded that pyrethroid exposure in the first and second trimesters was associated with poorer infants neurodevelopmental outcomes at one year of age, and these effects were particularly pronounced at high levels of pyrethroid exposure.

Neuromodulatory effect of cinnamon oil on behavioural disturbance, CYP1A1, iNOStranscripts and neurochemical alterations induced by deltamethrin in rat brain

The objective of this study was to investigate the influence of deltamethrin (DLM)on brain function and to find whether DLM-induced neurotoxicity is prevented by the treatment with cinnamon oil. Four groups of ten Wistar albino male rats each were used. Group I (control) received saline only. Group II received cinnamon oil alone at 0.5 mg/kg B.W. intraperitonally, whereas Group III received orally DLM alone at 6 mg/kg B.W. Groups IV was treated with cinnamon oil plus DLM for 21 days to induce neurotoxicity. Rat behaviour, brain acetylcholine esterase (AChE), serotonin, oxidative stress profile were assessed. Serum sampling for the assessment of corticosterone concentration was also carried out. Finally, we demonstrate the gene expression of CYP1A1 and iNOS and the histological picture of the brain. Considering the behaviour assessment, DLM administration alone caused neurobehavioral deficits manifested by anxiety-like behavior which represented ina marked decrease in the sleeping frequency and duration, and marked increase the digging frequency and a wake non-active behavior duration. Moreover, the open field result showed a significant decrease in central square entries and duration. The neurochemical analysis revealed that DLM significantly suppressed AChE activity and elevated serotonin and corticosterone concentrations. Furthermore, results revealed thatthe brain reduced glutathione (GSH) content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration were significantly altered in DLM treated rats. Neurochemical disturbances were confirmed by histopathological changes in the brain. Furthermore, DLM up-regulates the mRNA expression of brain CYP1A1 and iNOS. Co-treatment with cinnamon oil exhibited significant improvement in behavioural performance and the brain antioxidant capacities with an increase in AChE activity and diminished the concentration of serotonin, serum corticosterone and MDA. Cinnamon oil treatment resulted in down-regulation of CYP1A1 and iNOS and improve the histologically picture. In conclusion, cinnamon oil ameliorated DLM-induced neurotoxicity through preventing oxidative stress-induced genotoxicity and apoptosis of brain in rats.

Pyrethroid exposure and neurotoxicity: a mechanistic approach

Pyrethroids are a class of synthetic insecticides that are used widely in and around households to control the pest. Concerns about exposure to this group of pesticides are now mainly related to their neurotoxicity and nigrostriatal dopaminergic neurodegeneration seen in Parkinson’s disease. The main neurotoxic mechanisms include oxidative stress, inflammation, neuronal cell loss, and mitochondrial dysfunction. The main neurodegeneration targets are ion channels. However, other receptors, enzymes, and several signalling pathways can also participate in disorders induced by pyrethroids. The aim of this review is to elucidate the main mechanisms involved in neurotoxicity caused by pyrethroids deltamethrin, permethrin, and cypermethrin. We also review common targets and pathways of Parkinson’s disease therapy, including Nrf2, Nurr1, and PPARγ, and how they are affected by exposure to pyrethroids. We conclude with possibilities to be addressed by future research of novel methods of protection against neurological disorders caused by pesticides that may also find their use in the management/treatment of Parkinson’s disease.

The Role of CYP2E1 in the Drug Metabolism or Bioactivation in the Brain

Organisms have metabolic pathways that are responsible for removing toxic agents. We always associate the liver as the major organ responsible for detoxification of the body; however this process occurs in many tissues. In the same way, as in the liver, the brain expresses metabolic pathways associated with the elimination of xenobiotics. Besides the detoxifying role of CYP2E1 for compounds such as electrophilic agents, reactive oxygen species, free radical products, and the bioactivation of xenobiotics, CYP2E1 is also related in several diseases and pathophysiological conditions. In this review, we describe the presence of phase I monooxygenase CYP2E1 in regions of the brain. We also explore the conditions where protein, mRNA, and the activity of CYP2E1 are induced. Finally, we describe the relation of CYP2E1 in brain disorders, including the behavioral relations for alcohol consumption via CYP2E1 metabolism.

Vitamin E attenuates neurotoxicity induced by deltamethrin in rats

Background

The safety of Deltamethrin (DM) has been raised as a point of concern. The current investigation was envisaged to explore the responsiveness of oxidative stress parameters, DNA fragmentation and expression levels of TP53, cycloxygenase 2 (COX2) and cytochrome p4502E1 (CYP2E1) as toxicological endpoint in rats treated with DM. as well as attention was provided to the neuroprotective effect of vitamin E (VE).

Methods

Four different groups of rats were used in this study, group I served as control, group II received DM (0.6 mg/kg BW), group III received both DM plus VE and finally group IV received VE only (200 mg/kg BW). The treatment regimen was extending for one month for all groups and the brain tissues were collected for further analysis.

Results

The obtained results showed a highly statistically significant increase in lipid peroxidation (LPO) content, nitric oxide concentration, and DNA fragmentation percentage and expression level of CYP2E1, TP53 and COX2 genes, in addition statistical significant reduction in total antioxidant capacity in DM treated group as compared to control were detected. Oral administration of VE attenuated the neurotoxic effects of DM through improvement of oxidative status, DNA fragmentation percentage and suppressing the expression level of CYP2E1, TP53 and COX2 genes.

Conclusion

From this study we concluded that VE supplementation has beneficial impacts on DM neurotoxicity in rats through its antioxidant and antiapoptotic properties.

Allethrin induced toxicity in the male reproductive tract of rats contributes to disruption in the transcription of genes involved in germ cell production

Pyrethroids are known to be neurotoxic. However, their toxic effects including that of allethrin on the male reproductive tract are not elucidated. Adult male rats were treated orally with 25, 50, 100, and 150 mg/kg body weight allethrin every day for 60 days. Lipid peroxidation was increased (p < 0.001) in the caput, cauda, and testes. Nitric oxide production was increased (p < 0.001) in the caput, but unaltered in the cauda and testes. The activities of catalase, glutathione peroxidase, glutathione-S-transferase, and superoxide dismutase were decreased in the caput and cauda where as a decrease was observed in the testis obtained from allethrin treated rats. In the epididymides and testes, damage to tubular architecture, congestion, degeneration of epithelial cell lining, intestinal edema, and presence of dead or degenerating spermatids were observed in a dose dependent manner. The expression profile of genes involved in spermatogenesis (Tgf-beta1), sperm maturation (Spag11e), and sperm function (Defb22) were reduced (p < 0.001) in allethrin rats. The expression of p53 gene was decreased and increased phosphorylation of MAPK (p42/p44) expression was observed the male reproductive tract tissues of allethrin treated rats. Although earlier studies have reported the effects of allethrin inhalation because of the use of mosquito coils and vaporizers, our results for the first time prove that oral exposure to allethrin could affect fertility and may contribute to deregulation of cell cycle in the male reproductive tract.

Detection of transfluthrin and metofluthrin genotoxicity in the ST cross of the Drosophila Wing Spot Test

In this study, different concentrations of transfluthrin and metofluthrin have been assayed for genotoxicity by using the Wing Spot Test on Drosophila melanogaster. Standard cross was used in the experiment. Third-instar larvae that were trans-heterozygous for the two genetic markers mwh and flr(3) were treated at different concentrations (0.0103mgmL(-1), 0.103mgmL(-1) for transfluthrin and 6μgmL(-1), 60μgmL(-1) for metofluthrin) of the test compounds. Feeding ended with pupation of the surviving larvae and the genetic changes induced in somatic cells of the wing's imaginal discs lead to the formation of mutant clones on the wing blade. Results indicated that two experimental concentrations of transfluthrin and 60μgmL(-1) metofluthrin showed mutagenic and recombinogenic effects in both the marker-heterozygous (MH) flies and the balancer-heterozygous (BH) flies.