The Striatal DNA Damage and Neurodegenerations

Reactive oxygen species (ROS) are produced during normal metabolic reactions in living cells. ROS causes oxidative damage to many types of biomolecules. An age-related increase in oxidative damage to DNA and RNA has been described in the human neurons, which play a vital role in the progression of age-associated neurodegeneration. As dopamine metabolism is believed to be the primary source of ROS, oxidative insults correlate with dopamine levels in the striatum during the progression of neurodegenerative diseases. Parallel changes in dopamine concentrations and vesicular monoamine transporter 2 (VMAT2) binding densities in the striatum were observed. Besides Fenton oxidation taking place, the packing of cytosolic dopamine into synaptic vesicles by VMAT2 inhibits its autoxidation and subsequent decay of dopaminergic neurons. The female bias in the DNA damage in the late-stage Parkinson disease (PD) patients suggests that the sex-determining region of the Y chromosome (SRY) genes are critically involved. ROS are involved in regulating the rate of the aging procession in healthy cohorts and an increased life span of patients with neurodegenerative diseases via stimulation of protective stress responses. Moreover, the DNA repair pathway’s mechanism, as genetic modifiers determine the age at onset through a ROS-inducing mutation

Dopamine D1 + D3 receptor density may correlate with Parkinson disease clinical features

OBJECTIVE: Dopamine D2-like receptors - mainly dopamine D2 receptors (D2R) and dopamine D3 receptors (D3R) - are believed to be greatly involved in the pathology of Parkinson disease (PD) progression. However, these receptors have not been precisely examined in PD patients. Our aim was to quantitatively calculate the exact densities of dopamine D1 receptors (D1R), D2R, and D3R in control, Alzheimer disease (AD), and Lewy body disease (LBD) patients (including PD, Dementia with Lewy bodies, and Parkinson disease dementia); and analyze the relationship between dopamine receptors and clinical PD manifestations. METHODS: We analyzed the densities of D1R, D2R, and D3R in the striatum and substantia nigra (SN) using a novel quantitative autoradiography procedure previously developed by our group. We also examined the expression of D2R and D3R mRNA in the striatum by in situ hybridization. RESULTS: The results showed that although no differences of striatal D1R were found among all groups; D2R was significantly decreased in the striatum of PD patients when compared with control and AD patients. Some clinical manifestations: age of onset, PD stage, dopamine responsiveness, and survival time after onset; showed a better correlation with striatal D1R + D3R densities combined compared to D1R or D3R alone. INTERPRETATION: There is a possibility that we may infer the results in diagnosis, treatment, and prognosis of PD by detecting D1R + D3R as opposed to using dopamine D1 or D3 receptors alone. This is especially true for elderly patients with low D2R expression as is common in this disease

Microglia implicated in tauopathy in the striatum of neurodegenerative disease patients from genotype to phenotype

We found interactions between dopamine and oxidative damage in the striatum involved in advanced neurodegeneration, which probably change the microglial phenotype. We observed possible microglia dystrophy in the striatum of neurodegenerative brains. To investigate the interactions between oxidative damage and microglial phenotype, we quantified myeloperoxidase (MPO), poly (ADP-Ribose) (PAR), and triggering receptors expressed on myeloid cell 2 (TREM2) using enzyme-linked immunosorbent assay (ELISA). To test the correlations of microglia dystrophy and tauopathy, we quantified translocator protein (TSPO) and tau fibrils using autoradiography. We chose the caudate and putamen of Lewy body diseases (LBDs) (Parkinson\u27s disease, Parkinson\u27s disease dementia, and Dementia with Lewy body), Alzheimer\u27s disease (AD), and control brains and genotyped fo

Striatal oxidative damages and neuroinflammation correlate with progression and survival of Lewy body and Alzheimer diseases

Neurodegenerative diseases are a class of chronic and complex disorders featuring progressive loss of neurons in distinct brain areas. The mechanisms responsible for the disease progression in neurodegeneration are not fully illustrated. In this observational study, we have examined diverse biochemical parameters in the caudate and putamen of patients with Lewy body diseases (LBDs) and Alzheimer disease (AD), shedding some light on the involvement of oxidative damage and neuroinflammation in advanced neurodegeneration. We performed Spearman and Mantel-Cox analyses to investigate how oxidative stress and neuroinflammation exert comprehensive effects on disease progression and survival. Disease progression in LBDs correlated positively with poly (ADP-Ribose) and triggering receptors expressed on myeloid cell 2 levels in the striatum of LBD cohorts, indicating that potential parthanatos was a dominant feature of worsening disease progression and might contribute to switching microglial inflammatory phenotypes. Disease progression in AD corresponds negatively with 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) and myeloperoxidase concentrations in the striatum, suggesting that possible mitochondria dysfunction may be involved in the progression of AD via a mechanism of β-amyloid entering the mitochondria and subsequent free radicals generation. Patients with lower striatal 8-oxo-dG and myeloperoxidase levels had a survival advantage in AD. The age of onset also affected disease progression. Tissue requests for the postmortem biochemistry, genetics, and autoradiography studies were approved by the Washington University Alzheimer’s Disease Research Center (ADRC) Biospecimens Committee (ethics approval reference number: T1705, approval date: August 6, 2019). Recombinant DNA and Hazardous Research Materials were approved by the Washington University Environmental Health & Safety Biological Safety Committee (approval code: 3739, approval date: February 25, 2020). Radioactive Material Authorization was approved by the Washington University Environmental Health & Safety Radiation Safety Committee (approval code: 1056, approval date: September 18, 2019)