Disruption of the function of the primary motor cortex (M1) is thought to play a critical role in motor dysfunction in Parkinson’s disease (PD). Detailed information regarding the specific aspects of M1 circuits that become abnormal is lacking. We recorded single units and local field potentials (LFPs) of M1 neurons in unilateral 6-hydroxydopamine (6-OHDA) lesion rats and control rats to assess the impact of dopamine (DA) cell loss during rest and a forelimb reaching task. Our results indicated that M1 neurons can be classified into two groups (putative pyramidal neurons and putative interneurons) and that 6-OHDA could modify the activity of different M1 subpopulations to a large extent. Reduced activation of putative pyramidal neurons during inattentive rest and reaching was observed. In addition, 6-OHDA intoxication was associated with an increase in certain LFP frequencies, especially those in the beta range (broadly defined here as any frequency between 12 and 35 Hz), which become pathologically exaggerated throughout cortico-basal ganglia circuits after dopamine depletion. Furthermore, assessment of different spike-LFP coupling parameters revealed that the putative pyramidal neurons were particularly prone to being phase-locked to ongoing cortical oscillations at 12–35 Hz during reaching. Conversely, putative interneurons were neither hypoactive nor synchronized to ongoing cortical oscillations. These data collectively demonstrate a neuron type-selective alteration in the M1 in hemiparkinsonian rats. These alterations hamper the ability of the M1 to contribute to motor conduction and are likely some of the main contributors to motor impairments in PD.
Objective: CGG/GGC repeat expansion in FMR1 and NOTCH2NLC is reportedly associated with movement disorders; therefore, we hypothesized that the CGG repeat expansion in LRP12, NUTM2B-AS1, and GIPC1, which was previously identified in myopathy, might also be associated with movement-disorder phenotypes. Here, we investigated whether CGG repeat expansion in LRP12, NUTM2B-AS1, and GIPC1 presents in a cohort of patients with movement disorders. Methods: We screened for the CGG repeat expansion in LRP12, NUTM2B-AS1, and GIPC1 in 1,346 movementdisorder patients and 1,451 matched healthy controls. Results: No patients or controls harbored expanded CGG repeats in LRP12 or NUTM2B-AS1, whereas 16 patients harbored >40 CGG repeats in GIPC1, with 11 of these patients harboring >60 CGG repeats. One control individual harbored an expanded GIPC1 allele (83 CGG units), suggesting that approximately 1% of patients affected by movement disorders in our population might harbor GIPC1 CGG repeat expansion, with this likely extremely rare in healthy controls (<0.001). The clinical phenotypes of the GIPC1 CGG repeat-positive patients strongly resembled those in patients displaying NOTCH2NLC GGC repeat-positive movement disorders. Additionally, the GIPC1 CGG repeat-positive patients presented white-matter hyperintensities but without typical NOTCH2NLCrelated high-intensity signals in the corticomedullary junction. Furthermore, 44% of the GIPC1 CGG repeatpositive patients showed a cognitive deficit, and skin biopsies in 2 patients revealed deposition of intranuclear inclusions. Interpretation: The CGG repeat expansion in GIPC1 might be associated with movement-disorder phenotypes and lead to diseases related to intranuclear inclusions.
Background: Lacunar stroke accounts for a quarter of all strokes but little is known about the underlying pathological mechanisms. Analysis of serum metabolites may allow better understanding of the underlying biological processes. Mendelian randomization (MR) can provide information on the causality of associations. Aims: To identify causal relationships between serum metabolites and lacunar stroke. Methods: We applied a two-sample Mendelian randomization (MR) analysis to evaluate relationships between 486 serum metabolites and lacunar stroke. The inverse-variance weighted (IVW) method was used to estimate the causal relationship of the exposure on the outcome, while sensitivity analyses were performed using MR-Egger, weighted median and MR-PRESSO to eliminate the pleiotropy. We also performed a metabolic pathway analysis to identify potential metabolic pathways. Results: We identified 15 known (eight risk and seven protective) and 14 unknown serum metabolites associated with lacunar stroke. Among the known risk metabolites, two were lipids (1-linoleoylglycerophosphoethanolamine and dihomo-linolenate (20:3n3 or n6), five amino acids (kynurenine, isobutyrylcarnitine, aspartate, trans-4-hydroxyproline and 3-methyl-2-oxovalerate), and one a peptide (ADSGEGDFXAEGGGVR). The known protective metabolites included four lipids (4-androsten-3beta,17beta-diol disulfate 1, 1-palmitoleoylglycerophosphocholine, adrenate (22:4n6) and glycodeoxycholate), one amino acid (methionine) and two exogenous metabolites (homostachydrine and 2-methoxyacetaminophen sulphate). Metabolic pathway analysis identified several pathways that might be involved in the disease. Conclusion: We identified eight risk and seven protective human serum metabolites associated with lacunar stroke. Isobutyrylcarnitine was positively associated with an increased risk of lacunar stroke. In addition, 3-methyl-2-oxovalerate and aspartate may be involved in the disease pathogenesis through metabolic pathways.
Spinocerebellar ataxia 19/22 (SCA19/22) is a rare neurodegenerative disorder caused by mutations of the KCND3 gene, which encodes the Kv4. 3 protein. Currently, only 22 KCND3 single-nucleotide mutation sites of SCA19/22 have been reported worldwide, and detailed pathogenesis remains unclear. In this study, Sanger sequencing was used to screen 115 probands of cerebellar ataxia families in 67 patients with sporadic cerebellar ataxia and 200 healthy people to identify KCND3 mutations. Mutant gene products showed pathogenicity damage, and the polarity was changed. Next, we established induced pluripotent stem cells (iPSCs) derived from SCA19/22 patients. Using a transcriptome sequencing technique, we found that protein processing in the endoplasmic reticulum was significantly enriched in SCA19/22-iPS-derived neurons and was closely related to endoplasmic reticulum stress (ERS) and apoptosis. In addition, Western blotting of the SCA19/22-iPS-derived neurons showed a reduction in Kv4.3; but, activation of transcription factor 4 (ATF4) and C/EBP homologous protein was increased. Therefore, the c.1130 C>T (p.T377M) mutation of the KCND3 gene may mediate misfold and aggregation of Kv4.3, which activates the ERS and further induces neuron apoptosis involved in SCA19/22.
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