Environmental and genetic risk factors, and their interactions, contribute significantly to the etiology of neurodevelopmental disorders (NDDs). Recent epidemiology studies have implicated pyrethroid pesticides as an environmental risk factor for autism and developmental delay. Our previous research showed that low-dose developmental exposure to the pyrethroid pesticide deltamethrin in mice caused male-biased changes in the brain and in NDD-relevant behaviors in adulthood. Here, we used a metabolomics approach to determine the broadest possible set of metabolic changes in the adult male mouse brain caused by low-dose pyrethroid exposure during development. Using a litter-based design, we exposed mouse dams during pregnancy and lactation to deltamethrin (3 mg/kg or vehicle every 3 days) at a concentration well below the EPA-determined benchmark dose used for regulatory guidance. We raised male offspring to adulthood and collected whole brain samples for untargeted high-resolution metabolomics analysis. Developmentally exposed mice had disruptions in 116 metabolites which clustered into pathways for folate biosynthesis, retinol metabolism, and tryptophan metabolism. As a cross-validation, we integrated metabolomics and transcriptomics data from the same samples, which confirmed previous findings of altered dopamine signaling. These results suggest that pyrethroid exposure during development leads to disruptions in metabolism in the adult brain, which may inform both prevention and therapeutic strategies.

Glutamate excitotoxicity plays a critical role in neurodegeneration by triggering NMDA receptor hyperactivation, leading to elevated synaptic calcium levels and subsequent neuronal death. To better understand how glutamate affects neurons in neurological diseases, we conducted a comprehensive analysis of molecular changes at the transcriptome and kinome levels. We used primary cortical cultures from rat embryos to study glutamate‐induced excitotoxicity. Intermediate doses of glutamate (250 μM) produced significant neurotoxic effects, whereas high and low doses resulted in less cell mortality, aligning with previous findings related to calcium influx. Transcriptional analysis identified BTG2, NPAS4, and CCN1 as the most significantly differentially expressed genes following 250 μM glutamate treatment in neurons. Dkk2, a Wnt antagonist, exhibited the highest log fold change among the significantly differentially expressed genes. Gene set enrichment analysis identified 1127 significant pathways. Perturbagen analysis revealed 2811 unique concordant signatures and 1071 unique discordant signatures. Kinome array profiling indicated activation of PKA and PKG kinases, which regulate signaling pathways essential for synaptic plasticity‐related gene expression. Multi‐omic integration of transcriptome and kinome data revealed enrichment of response to oxidative stress, actin filament organization, and regulation of apoptotic processes pathways. The Wnt signaling pathway emerged as a pivotal factor in the early stages of axon differentiation and growth, as well as in shaping axonal behavior and dendrite development. Moreover, the interplay between MAPK and Wnt signaling pathways likely impacts cellular differentiation processes. Our findings highlight a prominent role for p38/MAPK and stress‐activated MAPK pathways, with specific activation of the MAPK/ERK signaling pathway in response to excitotoxic neuronal damage in vitro. In conclusion, glutamate excitotoxicity induces molecular changes at the transcriptome and kinome levels that include elements of the MAPK and WNT biological pathways. image

Neurodevelopmental disorders (NDDs) are a category of pervasive disorders of the developing nervous system with few or no recognized biomarkers. A significant portion of the risk for NDDs, including attention deficit hyperactivity disorder (ADHD), is contributed by the environment, and exposure to pyrethroid pesticides during pregnancy has been identified as a potential risk factor for NDD in the unborn child. We recently showed that low-dose developmental exposure to the pyrethroid pesticide deltamethrin in mice causes male-biased changes to ADHD- and NDD-relevant behaviors as well as the striatal dopamine system. Here, we used an integrated multiomics approach to determine the broadest possible set of biological changes in the mouse brain caused by developmental pyrethroid exposure (DPE). Using a litter-based, split-sample design, we exposed mouse dams during pregnancy and lactation to deltamethrin (3 mg/kg or vehicle every 3 days) at a concentration well below the EPA-determined benchmark dose used for regulatory guidance. We raised male offspring to adulthood, euthanized them, and pulverized and divided whole brain samples for split-sample transcriptomics, kinomics and multiomics integration. Transcriptome analysis revealed alterations to multiple canonical clock genes, and kinome analysis revealed changes in the activity of multiple kinases involved in synaptic plasticity, including the mitogen-activated protein (MAP) kinase ERK. Multiomics integration revealed a dysregulated protein-protein interaction network containing primary clusters for MAP kinase cascades, regulation of apoptosis, and synaptic function. These results demonstrate that DPE causes a multi-modal biophenotype in the brain relevant to ADHD and identifies new potential mechanisms of action. NEW & NOTEWORTHY: Here, we provide the first evidence that low-dose developmental exposure to the pyrethroid pesticide, deltamethrin, results in molecular disruptions in the adult mouse brain in pathways regulating circadian rhythms and neuronal growth (MAP kinase). This same exposure causes a neurodevelopmental disorder (NDD) relevant behavioral changes in adult mice, making these findings relevant to the prevention of NDDs.

Environmental and genetic risk factors, and their interactions, contribute significantly to the etiology of neurodevelopmental disorders (NDDs). Recent epidemiology studies have implicated pyrethroid pesticides as an environmental risk factor for autism and developmental delay. Our previous research showed that low-dose developmental exposure to the pyrethroid pesticide deltamethrin in mice caused male-biased changes in the brain and in NDD-relevant behaviors in adulthood. Here, we used a metabolomics approach to determine the broadest possible set of metabolic changes in the adult male mouse brain caused by low-dose pyrethroid exposure during development. Using a litter-based design, we exposed mouse dams during pregnancy and lactation to deltamethrin (3 mg/kg or vehicle every 3 days) at a concentration well below the EPA-determined benchmark dose used for regulatory guidance. We raised male offspring to adulthood and collected whole brain samples for untargeted high-resolution metabolomics analysis. Developmentally exposed mice had disruptions in 116 metabolites which clustered into pathways for folate biosynthesis, retinol metabolism, and tryptophan metabolism. As a cross-validation, we integrated metabolomics and transcriptomics data from the same samples, which confirmed previous findings of altered dopamine signaling. These results suggest that pyrethroid exposure during development leads to disruptions in metabolism in the adult brain, which may inform both prevention and therapeutic strategies. Highlights: Developmental pyrethroid exposure disrupts brain metabolism in adulthood Exposure disrupts metabolic pathways for folate, retinol, and tryptophan Exposure disrupts genetic and metabolic pathways for dopamine signaling

Translation: The University of Toledo Journal of Medical Sciences is the online journal launched by the University of Toledo. Manuscripts will be considered on the understanding that they report original work and are not under consideration for publication by any other journal. The journal publishes original articles reporting experimental results of basic or clinical research, case reports, and reviews. The journal uses a single blind peer review system and each manuscript, based on the results presented in its original submission, will be evaluated by two student reviewers and one faculty reviewer. This process will provide an opportunity for medical students, graduate students, residents, fellows and faculty to publish research observation in a timely manner.

Translation: The University of Toledo Journal of Medical Sciences is the online journal launched by the University of Toledo. Manuscripts will be considered on the understanding that they report original work and are not under consideration for publication by any other journal. The journal publishes original articles reporting experimental results of basic or clinical research, case reports, and reviews. The journal uses a single blind peer review system and each manuscript, based on the results presented in its original submission, will be evaluated by two student reviewers and one faculty reviewer. This process will provide an opportunity for medical students, graduate students, residents, fellows and faculty to publish research observation in a timely manner.