RESUMEN
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 (3â¯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.
Asunto(s)
Encéfalo , Nitrilos , Efectos Tardíos de la Exposición Prenatal , Piretrinas , Animales , Piretrinas/toxicidad , Encéfalo/metabolismo , Encéfalo/efectos de los fármacos , Encéfalo/crecimiento & desarrollo , Femenino , Masculino , Efectos Tardíos de la Exposición Prenatal/inducido químicamente , Efectos Tardíos de la Exposición Prenatal/metabolismo , Embarazo , Ratones , Nitrilos/toxicidad , Insecticidas/toxicidad , Ratones Endogámicos C57BL , MetabolómicaRESUMEN
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high-energy demand, and broad unmyelinated axonal arborisations. Impairments in the storage of dopamine compound this stress because of cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilising false fluorescent neurotransmitter 206 (FFN206) to visualise how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabelled dopamine in vesicles isolated from immortalised cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants and helps maintain the integrity of dopaminergic neurons.
Asunto(s)
Dopamina , Neuronas Dopaminérgicas , Glicoproteínas de Membrana , Proteínas del Tejido Nervioso , Vesículas Sinápticas , Animales , Dopamina/metabolismo , Vesículas Sinápticas/metabolismo , Vesículas Sinápticas/efectos de los fármacos , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/genética , Ratones , Neuronas Dopaminérgicas/metabolismo , Neuronas Dopaminérgicas/efectos de los fármacos , Proteínas del Tejido Nervioso/metabolismo , Proteínas del Tejido Nervioso/genética , Ratones Endogámicos C57BL , Humanos , Cuerpo Estriado/metabolismo , Cuerpo Estriado/efectos de los fármacos , MasculinoRESUMEN
Centrioles are subcellular organelles found at the cilia base with an evolutionarily conserved structure and a shock absorber-like function. In sperm, centrioles are found at the flagellum base and are essential for embryo development in basal animals. Yet, sperm centrioles have evolved diverse forms, sometimes acting like a transmission system, as in cattle, and sometimes becoming dispensable, as in house mice. How the essential sperm centriole evolved to become dispensable in some organisms is unclear. Here, we test the hypothesis that this transition occurred through a cascade of evolutionary changes to the proteins, structure, and function of sperm centrioles and was possibly driven by sperm competition. We found that the final steps in this cascade are associated with a change in the primary structure of the centriolar inner scaffold protein FAM161A in rodents. This information provides the first insight into the molecular mechanisms and adaptive evolution underlying a major evolutionary transition within the internal structure of the mammalian sperm neck.
Asunto(s)
Centriolos , Semen , Masculino , Animales , Bovinos , Ratones , Centriolos/metabolismo , Espermatozoides/metabolismo , Proteínas/metabolismo , Cilios , MamíferosRESUMEN
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.
RESUMEN
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 folate metabolism in the adult brain, which may inform both prevention and therapeutic strategies.
RESUMEN
Patients with epilepsy are significantly burdened by the disease due to long-term health risks, the severe side effect profiles of anti-epileptic drugs, and the strong possibility of pharmacoresistant refractory seizures. New animal models of epilepsy with unique characteristics promise to further research to address these ongoing problems. Here, we characterize a newly developed line of prairie voles (Microtus ochrogaster, UTol:HIC or "Toledo" line) that presents with a hereditary, adult-onset, handling-induced convulsion phenotype. Toledo voles were bred for four generations and tested to determine whether the observed phenotype was consistent with epileptic seizures. Toledo voles maintained a stable 22 % incidence of convulsions across generations, with an average age of onset of 12-16 weeks. Convulsions in Toledo voles were reliably evoked by rodent seizure screens and were phenotypically consistent with murine seizures. At the colony level, Toledo voles had a 7-fold increase in risk for sudden unexpected death from unknown causes, which parallels sudden unexpected death in epilepsy (SUDEP) in human patients. Finally, convulsions in Toledo voles were reduced or prevented by treatment with the anti-epileptic drug levetiracetam. Taken in combination, these results suggest that convulsions in Toledo voles may be epileptic seizures. The Toledo prairie vole strain may serve as a new rodent model of epilepsy in an undomesticated, outbred species.
Asunto(s)
Epilepsia , Pradera , Humanos , Animales , Ratones , Lactante , Convulsiones/tratamiento farmacológico , Convulsiones/genética , Epilepsia/tratamiento farmacológico , Epilepsia/genética , Levetiracetam , Arvicolinae/fisiologíaRESUMEN
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high energy demand, and broad unmyelinated axonal arborizations. Impairments in the storage of dopamine compound this stress due to cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilizing false fluorescent neurotransmitter 206 (FFN206) to visualize how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabeled dopamine in vesicles isolated from immortalized cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants, and helps maintain the integrity of dopaminergic neurons.
RESUMEN
Neurodevelopmental disorders (NDDs) are a widespread and growing public health challenge, affecting as many as 17% of children in the United States. Recent epidemiological studies have implicated ambient exposure to pyrethroid pesticides during pregnancy in the risk for NDDs in the unborn child. Using a litter-based, independent discovery-replication cohort design, we exposed mouse dams orally during pregnancy and lactation to the Environmental Protection Agency's reference pyrethroid, deltamethrin, at 3â mg/kg, a concentration well below the benchmark dose used for regulatory guidance. The resulting offspring were tested using behavioral and molecular methods targeting behavioral phenotypes relevant to autism and NDD, as well as changes to the striatal dopamine system. Low-dose developmental exposure to the pyrethroid deltamethrin (DPE) decreased pup vocalizations, increased repetitive behaviors, and impaired both fear conditioning and operant conditioning. Compared with control mice, DPE mice had greater total striatal dopamine, dopamine metabolites, and stimulated dopamine release, but no difference in vesicular dopamine capacity or protein markers of dopamine vesicles. Dopamine transporter protein levels were increased in DPE mice, but not temporal dopamine reuptake. Striatal medium spiny neurons showed changes in electrophysiological properties consistent with a compensatory decrease in neuronal excitability. Combined with previous findings, these results implicate DPE as a direct cause of an NDD-relevant behavioral phenotype and striatal dopamine dysfunction in mice and implicate the cytosolic compartment as the location of excess striatal dopamine.
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A subset of people exposed to a traumatic event develops post-traumatic stress disorder (PTSD), which is associated with dysregulated fear behavior. Genetic variation in SLC18A2, the gene that encodes vesicular monoamine transporter 2 (VMAT2), has been reported to affect risk for the development of PTSD in humans. Here, we use transgenic mice that express either 5% (VMAT2-LO mice) or 200% (VMAT2-HI mice) of wild-type levels of VMAT2 protein. We report that VMAT2-LO mice have reduced VMAT2 protein in the hippocampus and amygdala, impaired monoaminergic vesicular storage capacity in both the striatum and frontal cortex, decreased monoamine metabolite abundance and a greatly reduced capacity to release dopamine upon stimulation. Furthermore, VMAT2-LO mice showed exaggerated cued and contextual fear expression, altered fear habituation, inability to discriminate threat from safety cues, altered startle response compared with wild-type mice and an anxiogenic-like phenotype, but displayed no deficits in social function. By contrast, VMAT2-HI mice exhibited increased VMAT2 protein throughout the brain, higher vesicular storage capacity and greater dopamine release upon stimulation compared with wild-type controls. Behaviorally, VMAT2-HI mice were similar to wild-type mice in most assays, with some evidence of a reduced anxiety-like responses. Together, these data show that presynaptic monoamine function mediates PTSD-like outcomes in our mouse model, and suggest a causal link between reduced VMAT2 expression and fear behavior, consistent with the correlational relationship between VMAT2 genotype and PTSD risk in humans. Targeting this system is a potential strategy for the development of pharmacotherapies for disorders like PTSD.
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Miedo , Trastornos por Estrés Postraumático/genética , Proteínas de Transporte Vesicular de Monoaminas/genética , Amígdala del Cerebelo/metabolismo , Amígdala del Cerebelo/fisiología , Animales , Señales (Psicología) , Dopamina/metabolismo , Femenino , Habituación Psicofisiológica , Hipocampo/metabolismo , Hipocampo/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Conducta Social , Proteínas de Transporte Vesicular de Monoaminas/metabolismoRESUMEN
RATIONALE: Love has long been referred to as an addiction in literature and poetry. Scientists have often made comparisons between social attachment processes and drug addiction, and it has been suggested that the two may share a common neurobiological mechanism. Brain systems that evolved to govern attachments between parents and children and between monogamous partners may be the targets of drugs of abuse and serve as the basis for addiction processes. OBJECTIVES: Here, we review research on drug addiction in parallel with research on social attachments, including parent-offspring attachments and social bonds between mating partners. This review focuses on the brain regions and neurochemicals with the greatest overlap between addiction and attachment and, in particular, the mesolimbic dopamine (DA) pathway. RESULTS: Significant overlap exists between these two behavioral processes. In addition to conceptual overlap in symptomatology, there is a strong commonality between the two domains regarding the roles and sites of action of DA, opioids, and corticotropin-releasing factor. The neuropeptides oxytocin and vasopressin are hypothesized to integrate social information into attachment processes that is not present in drug addiction. CONCLUSIONS: Social attachment may be understood as a behavioral addiction, whereby the subject becomes addicted to another individual and the cues that predict social reward. Understandings from both fields may enlighten future research on addiction and attachment processes.
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Conducta Adictiva/psicología , Amor , Apego a Objetos , Animales , Conducta Adictiva/fisiopatología , Encéfalo/fisiología , Dopamina/metabolismo , Humanos , Apareamiento , Relaciones Padres-Hijo , Recompensa , Conducta Social , Trastornos Relacionados con Sustancias/fisiopatología , Trastornos Relacionados con Sustancias/psicologíaRESUMEN
Despite significant evidence that opioids are involved in attachment by mediating social reward and motivation, the role of opioids in the formation of adult social attachments has not been explored. We used the socially monogamous prairie vole (Microtus ochrogaster) to explore the role of endogenous opioids in social bonding by examining partner preference formation in female prairie voles. We hypothesized that µ-opioid receptors (MORs) in the striatum have a critical role in partner preference formation. We therefore predicted that peripheral administration of an opioid receptor antagonist would inhibit partner preference formation, and more specifically, that µ-opioid selective receptor blockade within the striatum would inhibit partner preference formation. To test our hypotheses, we first administered the non-selective opioid antagonist naltrexone peripherally to females during an 18-h cohabitation with a male and later tested the female with a partner preference test (PPT). Females showed a dose schedule-dependent decrease in partner preference in the PPT, with females in the continuous dose group displaying stranger preferences. Next, we administered microinjections of the MOR selective antagonist D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP) into either the nucleus accumbens shell (NAS) or the caudate-putamen (CP) immediately before a 24-h cohabitation with a male, and later tested the female with a PPT. Females receiving CTAP into the CP, but not the NAS, showed no preference in the PPT, indicating an inhibition of partner preference formation. We show here for the first time that MORs modulate partner preference formation in female prairie voles by acting in the CP.
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Cuerpo Estriado/metabolismo , Apareamiento , Receptores Opioides mu/metabolismo , Conducta Sexual Animal/fisiología , Conducta Social , Factores de Edad , Animales , Arvicolinae , Cuerpo Estriado/efectos de los fármacos , Femenino , Masculino , Microinyecciones , Naltrexona/administración & dosificación , Péptidos Opioides/administración & dosificación , Receptores Opioides mu/antagonistas & inhibidores , Receptores Opioides mu/fisiología , Conducta Sexual Animal/efectos de los fármacosRESUMEN
The partner preference test (PPT) is commonly used to examine sexual and social preferences in rodents. The test offers experimental subjects a choice between two stimulus animals, and time spent with each is used to calculate a preference score. In monogamous prairie voles (Microtus ochrogaster), the PPT has been paramount to the study of pair bonding. Although powerful, use of the PPT in voles has depended primarily on human manual scoring. Manual scoring is time-consuming and is susceptible to bias and fatigue, limiting the use of the PPT in high-throughput studies. Here we compared manual scoring (real-time and 16x) and two automated scoring metrics: "social proximity" and "immobile social contact". We hypothesized that "immobile social contact" would provide data most comparable to manually scored "huddling", and thus be the most sensitive measure of partner preference in prairie voles. Each automated metric produced data that highly correlated with manual scoring (R>0.90); however, "immobile social contact" more closely reflected manually scored huddling (R=0.99; P<0.001). "Social proximity" and "immobile social contact" were then used to detect group partner preferences in four data sets that varied by cohabitation length and sex. "Immobile social contact" revealed a significant partner preference in each data set; "social proximity" detected partner preferences in only three of the four. Our results demonstrate the utility of automated systems in high-throughput PPTs, and further confirm that automated systems capable of scoring "immobile social contact" yield results indistinguishable from manual scoring.
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Arvicolinae/fisiología , Preferencia en el Apareamiento Animal/fisiología , Psicología Experimental/instrumentación , Conducta Sexual Animal/fisiología , Agresión/fisiología , Animales , Automatización , Calibración , Femenino , Masculino , Ovariectomía , Medio Social , Grabación en VideoRESUMEN
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