Neurobiology of Disease

Processed data with mean and standar error of the mean.

This dataset contains all data for published figures and supplementary figures in the manuscript "Developmental exposure to the organochlorine pesticide dieldrin causes male-specific exacerbation of α-synuclein-preformed fibril-induced toxicity and motor deficits". GraphPad Prism files can be viewed in the free Viewer mode or data can be extracted by viewing files in a text editor. R and RStudio are freely available for running Rmd files. file_list.txt includes a list of all files included in this dataset Abstract: Human and animal studies have shown that exposure to the organochlorine pesticide dieldrin is associated with increased risk of Parkinson’s disease (PD). Previous work showed that developmental dieldrin exposure increased neuronal susceptibility to MPTP toxicity in male C57BL/6 mice, possibly via changes in dopamine (DA) packaging and turnover. However, the relevance of the MPTP model to PD pathophysiology has been questioned. We therefore studied dieldrin-induced neurotoxicity in the α-synuclein (α-syn)-preformed fibril (PFF) model, which better reflects the α-syn pathology and toxicity observed in PD pathogenesis. Specifically, we used a “two-hit” model to determine whether developmental dieldrin exposure increases susceptibility to α-syn PFF-induced synucleinopathy. Dams were fed either dieldrin (0.3 mg/kg, every 3-4 days) or vehicle corn oil starting 1 month prior to breeding and continuing through weaning of pups at postnatal day 22. At 12 weeks of age, male and female offspring received intrastriatal PFF or control saline injections. Consistent with the male-specific increased susceptibility to MPTP, our results demonstrate that developmental dieldrin exposure exacerbates PFF-induced toxicity in male mice only. Specifically, in male offspring, dieldrin exacerbated PFF-induced motor deficits on the challenging beam and increased DA turnover in the striatum 6 months after PFF injection. However, male offspring showed neither exacerbation of phosphorylated α-syn (pSyn) aggregation in the substantia nigra (SN) at 1 or 2 months post-PFF injection, nor exacerbation of PFF-induced TH and NeuN loss in the SN 6 months post-PFF injection. Collectively, these data indicate that developmental dieldrin exposure produces a male-specific increase in neuronal vulnerability to synucleinopathy. This sex-specific result is consistent with both previous work in the MPTP model, our previously reported sex-specific effects of this exposure paradigm on the male and female epigenome, and the higher prevalence and more severe course of PD in males. The novel two-hit environmental toxicant/PFF exposure paradigm established in this project can be used to explore the mechanisms by which other PD-related exposures alter neuronal vulnerability to synucleinopathy in sporadic PD.

Raw data files for preclinical studies in PSEN2 KO mice.

All resource for present study

We attached the independent replicates of Western blot analyses in the supplementary section that were used in various quantifications. The regions of line rectangles in these blots/gels, as representative images, were used in Figures of the main Text. In the Fig. 1e: the levels of hippocampal NF-H protein in seipin-sKO mice (sKO) and seipin-nKO mice (nKO) were lower than those of WT mice. In the Fig. 2a: the levels of tau protein in hippocampus of seipin-sKO mice, seipin-nKO mice and seipin-aKO mice (aKO) were not altered. In the Fig. 2b: the levels of oligomer tau protein were increased in seipin-sKO mice and seipin-nKO mice. In the Fig. 2c: the levels of hippocampal tau phosphorylation at Thr212/Ser214 and Ser202/Thr205 were increased in seipin-sKO mice and seipin-nKO mic. In the Fig. 3a: the levels of PPARγ protein were decreased in hippocampus of seipin-sKO mice and seipin-nKO mice. In the Fig. 3b: the administration of PPARγ agonist rosiglitazone (rosi) for 7 days could correct the increased tau phosphorylation at Thr212/Ser214 and Ser202/Thr205 in seipin-sKO mice and seipin-nKO mice. In the Fig. 4a: seipin-sKO mice and seipin-nKO mice showed an increase in the GSK3β phosphorylation at Tyr21 and a decrease at Ser9, which were corrected by rosi. In the Fig. 4b: the treatment with AR-A014418 (AR) corrected the increased tau phosphorylation at Thr212/Ser214 and Ser202/Thr205 in seipin-nKO mice. In the Fig. 5a&5b: the phosphorylation of Akt and mTOR was elevated in seipin-sKO mice and seipin-nKO mice, which were corrected by rosi. In the Fig. 5c&5d: seipin-sKO mice and seipin-nKO mice showed a decrease in the ratio of LC3II/I and an elevation of p62 protein, which was rescued by the PI3K inhibitor LY294002 (LY) and mTOR inhibitor rapamycin (Rap), but not AR. In the Fig. 5e&5f: the administration of LY and Rap reduced the levels of oligomer tau protein and tau phosphorylation at Thr212/Ser214 and Ser202/Thr205 in seipin-nKO mice. In the Fig. 6c: the increased phosphorylation of JNK in seipin-sKO mice were corrected by treatment with rosi for 30 days. In the Fig. 6d: the P38 phosphorylation in seipin-sKO mice was not altered. In the Fig. 6e: the increased phosphorylation of tau at Ser396 in seipin-sKO mice was prevented by treatment with rosi for 30 days and the JNK inhibitor SP600125 (SP).

Schematic illustration representing postsynaptic proteins associated to ASD. These proteins are involved in different synaptic functions, either directly (ion channels and glutamate receptors), or indirectly, including transmembrane heterophilic (NLGNs) and homophilic (NrCAM) cell-adhesion molecules, and scaffolding proteins (PSD-95, Shank, Homer), that link transmembrane and membrane-associated protein complexes with the underlying actin cytoskeleton. Additional cellular functions may influence synaptic activity in ASD, such as alternative splicing (PTEN, RBFOX1, nSR100/SRRM4), RNA editing (FMR1, FXR1), transcription (FOXP1, FOXP2, TBR1, TSHZ3), translation (FMR1), degradation (UBE3A), and mitochondrial activity (AGC1).

Figure 2. CDGI mediates the M1R modulation of dendritic excitability but not the M1R modulation of somatic excitability. (A and B) Sagittal sections through the brains of CDGI knockout mice in which the direct pathway was visualized (red) in D1-tdTomato mice (A) and the indirect pathway was visualized (green) in D2-GFP mice. (C) Sample somatic voltage changes evoked by 120pA current injections in iSPNs from WT (black) and CDGI-KO (red) before and after bath application of oxo-M (10 µM). (C-D) Current-response curves of iSPNs from WT (B, n=5 cells) and CDGI-KO mice (C, n=7 cells). Somatic excitability of iSPNs was similarly enhanced by oxo-M in WT and CDGI-KO. (E) Sample somatic recordings in response to 140pA current injections in dSPNs from WT (black) and CDGI KO (red) before and after bath application of oxo-M (10 µM). (F-H) Current-response curves of dSPNs from WT (E) and CDGI-KO (F) mice (n=4-6). (I) Trains of five EPSPs were evoked by stimulation of glutamatergic afferent fibers at 40 Hz. Oxo-M (10 µM) increased EPSP summation in iSPNs of WT, but not in CDGI-KO or when M1Rs were blocked by M1R antagonist VU0255035 in WT (5 M). (J) Box plot showing the effect of oxoM on synaptic summation. The EPSP5/EPSP1 ratio was increased by oxoM in iSPNs of WT (p = 0.002, Wilcoxon test; n = 10), but not in iSPNs of 27 CDGI-KO mice (p = 0.25, n = 9) or in iSPNs of WT mice in the presence of VU0255035 (p = 0.69, n = 6). (K) Box plot showing the effect of oxoM on the kinetics of synaptic response. The decay time constant of EPSP5 was significantly increased by oxoM in iSPNs of WT (p = 0.002); but not when CDGI was genetically deleted (p = 0.65) or when M1R was pharmacologically blocked (p = 0.84).

Figure 2 legend Upper panel. In control condition, visual sensory inputs from in- dividual’s face are encoded by the face recognition system. At system level (a), this process implies functional and structural modifications in multiple brain regions, whereas at cellular level (b), this promotes the induction of distinct forms of synaptic plasticity, such as long-term potentiation and long-term depression (LTP, LTD, respectively). Lower panel. Wearing face masks consis- tently reduces the amount of information, by excluding the lower part of the face, including nose and mouth. Thus, both at system and cellular level, such mismatch impairs long-term functional and structural plasticity. In particular, at synaptic level, LTP induction will be favored, whereas LTD will be impaired. The black traces indicate the excitatory postsynaptic potentials in control condition; the red traces represent the long-term changes in synaptic efficacy after the induction protocol.

Raw data of Figure 5 - (D) Summary plots of Tau values (left) and AMPA/NMDA ratio (right), measured from Gnal+/+ and Gnal+/- EPSCs showing no significant difference between genotypes (Tau: Gnal+/+, 9.47 ± 0.50 ms, n=31; Gnal+/-, 10.05 ± 0.66 ms, n=27; p=0.4832; AMPA/NMDA ratio: Gnal+/+ , 1.27 ± 0.14, n=10; Gnal+/-, 1.24 ± 0.13, n=15; Mann Whitney test p=0.9779). (E) Summary plot of PPR values showing similar facilitation in both genotypes. Each data point represents mean ± SEM (Gnal+/+, n=30, 50 ms: 1.22 ± 0.04; 100 ms: 1.16 ± 0.03; 150 ms: 1.11 ± 0.40; Gnal+/-, n=25, 50 ms: 1.28 ± 0.03; 100 ms: 1.17 ± 0.03; 150 ms: 1.09 ± 0.02; two-way ANOVA and Bonferroni posttest: ISI p<0.0001, genotype p=0.2405).