Project description:Despite the prevalence and high heritability of Attention-Deficit/Hyperactivity Disorder (ADHD), genetic etiology remains elusive. Clinical evidence points in part to reduced function of the striatum, but which specific genes are differentially expressed and how they sculpt striatal physiology to predispose ADHD are not well understood. As an exploratory tool, a polygenic mouse model of ADHD was recently developed through selective breeding for high home cage activity. Relative to the Control line, the High-Active line displays hyperactivity and motor impulsivity which are ameliorated with amphetamine. This study compared gene expression in the striatum between Control and High-Active mice to develop a coherent hypothesis for how genes might affect striatal physiology and predispose ADHD-like symptoms. To this end, striatal transcriptomes of High-Active and Control mice were analyzed after mice were treated with saline or amphetamines. The pseudogene Gm6180 for n-cofilin (Cfl1) displayed 20-fold higher expression in High-Active mice corresponding with reduced Cfl1 expression suggesting synaptic actin dysregulation. Latrophilin 3 (Lphn3), which is associated with ADHD in human populations and is involved in synapse structure, and its ligand fibronectin leucine rich transmembrane protein 3 (Flrt3), were downregulated in High-Active mice. Multiple genes were altered in High-Active mice in a manner predicted to downregulate the canonical Wnt pathway. A smaller and different set of genes including glyoxalase (Glo1) were differentially regulated in High-Active as compared to Control in response to amphetamine. Together, results suggest genes involved in excitatory synapse regulation and maintenance are downregulated in ADHD-like mice. Consistent with the molecular prediction, stereological analysis of the striatum from a separate set of mice processed for imunohistochemical detection of synaptophysin revealed approximately a 46% reduction in synaptophysin immunoreactivity in High-Active relative to Control. Results provide a new set of molecular targets related to synapse maintenance for the next generation of ADHD medicines.

Project description:ADHD is the most common neurobehavioral disorder in school-aged children. In addition to genetic factors, environmental influences or gene x environmental interactions also play an important role in ADHD. One example of a well studied environmental risk factor for ADHD is exposure to polychlorinated biphenyls (PCBs). In this study, we investigated whether the well-established genetic model of ADHD based on the Spontaneously Hypertensive Rat (SHR) and a well established PCB-based model of ADHD exhibited similar molecular changes in brain circuits involved in ADHD. The brains from 28 male rats (8 SHR, 8 Sprague-Dawley (SD) controls, 8 Wistar-Kyoto (WKY) controls, and 4 PCB-exposed SD rats) were harvested at postnatal day 55-65 and RNA was isolated from six brain regions of interest. The RNA was analyzed for differences in expression of a set of 308 probe sets interrogating 218 unique genes considered highly relevant to ADHD or epigenetic gene regulation using the Rat RAE 230 2.0 GeneChip (Affymetrix). Selected observations were confirmed by real time quantitative RT-PCR. The results show that the expression levels of genes Gnal, COMT, Adrbk1, Ntrk2, Hk1, Syt11 and Csnk1a1 were altered in both the SHR rats and the PCB-exposed SD rats. Arrb2, Stx12, Aqp6, Syt1, Ddc and Pgk1 expression levels were changed only in the PCB-exposed SD rats. Genes with altered expression only in the SHRs included Oprm1, Calcyon, Calmodulin, Lhx1 and Hes6.The epigenetic genes Crebbp, Mecp2 and Hdac5 are significantly altered in both models. The data provide strong evidence that genes and environment can affect different set of genes in two different models of ADHD and yet result in the similar disease-like symptoms. The brains from 28 male rats (8 SHR, 8 Sprague-Dawley (SD) controls, 8 Wistar-Kyoto (WKY) controls, and 4 PCB-exposed SD rats) were harvested at postnatal day 55-65 and RNA was isolated from six brain regions of interest. The RNA was analyzed for differences in expression of a set of 308 probe sets interrogating 218 unique genes considered highly relevant to ADHD or epigenetic gene regulation using the Rat RAE 230 2.0 GeneChip (Affymetrix). Selected observations were confirmed by real time quantitative RT-PCR.

Project description:Parkinsonâs disease (PD), the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression, or the A53T mutation, of the presynaptic protein alpha-synuclein (SNCA). PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons. Here, we used two mouse lines overexpressing human A53T-SNCA around ages 6 and 18 months and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. High pressure liquid chromatography analysis of striatal neurotransmitter content demonstrated that dopamine (DA) levels correlated directly with the level of expression of SNCA, an observation also observed in SNCA deficient mice. In the striatum of aged A53TSNCA overexpressing mice, where DA levels were elevated, a paradoxical upregulation of dopamine receptors DRD1A and DRD2 was detected by immunoblots and autoradiography, findings compatible with the notion of abnormal vesicle release. Extensive transcriptome studies via microarrays and quantitative real-time RT-PCR validation of altered Homer1, Cb1, Atf2 and Pde7b transcript levels indicated a progressive reduction in the postsynaptic DA response. As functional consequences, long term depression was absent in corticostriatal slices from aged transgenic mice and an insidious decrease of spontaneous locomotor activity of these animals was found in open field tests. Taken together, the dysfunctional neurotransmission and decreased synaptic plasticity seen in the A53T-SNCA overexpressing mice reflects early functional changes within the basal ganglia resulting from synucleinopathy prior to frank neurodegeneration. Thus, preclinical stages of PD may be modeled in this mouse. Parkinsonâs disease (PD), the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression, or the A53T mutation, of the presynaptic protein alpha-synuclein (SNCA). PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons. Here, we used two mouse lines overexpressing human A53T-SNCA around ages 6 and 18 months and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. High pressure liquid chromatography analysis of striatal neurotransmitter content demonstrated that dopamine (DA) levels correlated directly with the level of expression of SNCA, an observation also observed in SNCA deficient mice. In the striatum of aged A53TSNCA overexpressing mice, where DA levels were elevated, a paradoxical upregulation of dopamine receptors DRD1A and DRD2 was detected by immunoblots and autoradiography, findings compatible with the notion of abnormal vesicle release. Extensive transcriptome studies via microarrays and quantitative real-time RT-PCR validation of altered Homer1, Cb1, Atf2 and Pde7b transcript levels indicated a progressive reduction in the postsynaptic DA response. As functional consequences, long term depression was absent in corticostriatal slices from aged transgenic mice and an insidious decrease of spontaneous locomotor activity of these animals was found in open field tests. Taken together, the dysfunctional neurotransmission and decreased synaptic plasticity seen in the A53T-SNCA overexpressing mice reflects early functional changes within the basal ganglia resulting from synucleinopathy prior to frank neurodegeneration. Thus, preclinical stages of PD may be modeled in this mouse. Tissue was dissected from the brain of 6 months old (2 WT / 2 TgA / 2 TgB striata, 2 WT / 2 TgA / 2 TgB brainstems/midbrains, 2 WT / 2 TgA / 2 TgB cerebella) and of 18+ months old mice (4 WT / 2 TgA / 2 TgB striata, 6 WT / 4 TgA / 3 TgB brainstems/midbrains, 6 WT / 5 TgA / 4 TgB cerebella). Tissues from individual, particularly old mice up to 28 months age were included here to strengthen the definition of progression markers reflecting old age.

Project description:Parkinson’s disease (PD), the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression, or the A53T mutation, of the presynaptic protein alpha-synuclein (SNCA). PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons. Here, we used two mouse lines overexpressing human A53T-SNCA around ages 6 and 18 months and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. High pressure liquid chromatography analysis of striatal neurotransmitter content demonstrated that dopamine (DA) levels correlated directly with the level of expression of SNCA, an observation also observed in SNCA deficient mice. In the striatum of aged A53TSNCA overexpressing mice, where DA levels were elevated, a paradoxical upregulation of dopamine receptors DRD1A and DRD2 was detected by immunoblots and autoradiography, findings compatible with the notion of abnormal vesicle release. Extensive transcriptome studies via microarrays and quantitative real-time RT-PCR validation of altered Homer1, Cb1, Atf2 and Pde7b transcript levels indicated a progressive reduction in the postsynaptic DA response. As functional consequences, long term depression was absent in corticostriatal slices from aged transgenic mice and an insidious decrease of spontaneous locomotor activity of these animals was found in open field tests. Taken together, the dysfunctional neurotransmission and decreased synaptic plasticity seen in the A53T-SNCA overexpressing mice reflects early functional changes within the basal ganglia resulting from synucleinopathy prior to frank neurodegeneration. Thus, preclinical stages of PD may be modeled in this mouse. Parkinson’s disease (PD), the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression, or the A53T mutation, of the presynaptic protein alpha-synuclein (SNCA). PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons. Here, we used two mouse lines overexpressing human A53T-SNCA around ages 6 and 18 months and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. High pressure liquid chromatography analysis of striatal neurotransmitter content demonstrated that dopamine (DA) levels correlated directly with the level of expression of SNCA, an observation also observed in SNCA deficient mice. In the striatum of aged A53TSNCA overexpressing mice, where DA levels were elevated, a paradoxical upregulation of dopamine receptors DRD1A and DRD2 was detected by immunoblots and autoradiography, findings compatible with the notion of abnormal vesicle release. Extensive transcriptome studies via microarrays and quantitative real-time RT-PCR validation of altered Homer1, Cb1, Atf2 and Pde7b transcript levels indicated a progressive reduction in the postsynaptic DA response. As functional consequences, long term depression was absent in corticostriatal slices from aged transgenic mice and an insidious decrease of spontaneous locomotor activity of these animals was found in open field tests. Taken together, the dysfunctional neurotransmission and decreased synaptic plasticity seen in the A53T-SNCA overexpressing mice reflects early functional changes within the basal ganglia resulting from synucleinopathy prior to frank neurodegeneration. Thus, preclinical stages of PD may be modeled in this mouse.

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	SRR7480250_2.fastq.gz	Fastqsanger.gz
	SRR7480241_1.fastq.gz	Fastqsanger.gz

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Striatal transcriptome of a mouse model of ADHD reveals a pattern of synaptic remodeling

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