BACKGROUND: Over activation of the DNA repairing enzyme, poly (ADP-ribose) polymerase (PARP) in response to oxidative damage of DNA appears to play a role in cellular death in neurodegenerative diseases. Previous data suggested that PARP immunoreactivity (IR) was increased in the white and gray matter in spinal cord of the sporadic amyotrophic lateral sclerosis (sALS), predominantly in cells with astroglial morphology. METHODS: In the present study, we evaluated whether the PARP expression was present widespread in various regions of brain tissue including the motor cortex, parietal cortex and cerebellum. RESULTS: By western blot, PARP-IR in motor cortex from sALS patients, compared to the same region from age-matched normal controls, was also significantly increased (p=0.006). Importantly, PARP-IR was also increased in the parietal cortex, and cerebellum of sALS patients compared to the controls, in regions that are usually clinically unaffected in ALS (p=0.043, p=0.035, respectively). In addition, increased PARP expression in ALS was more prominent compared to Alzheimer's brain. Immunohistochemistry revealed that PARP staining was more significant in the cortical neurons and in the subcortical white matter glial cells from sALS patients compared to normal controls and Alzheimer's disease. CONCLUSIONS: The data demonstrate that increase in PARP-IR is not limited only to the vulnerable motor cortex. Furthermore, PARP-IR is present in both cortical neuronal and subcortical glial cells. The data suggest that widespread cellular stress on neuronal and glial cells is present in the brain of sporadic ALS patients.
Alzheimer Disease ; Amyotrophic Lateral Sclerosis* ; Blotting, Western ; Brain* ; Cerebellum ; DNA ; DNA Repair ; Humans ; Immunohistochemistry ; Motor Cortex ; Motor Neurons ; Neurodegenerative Diseases ; Neuroglia ; Neurons* ; Rabeprazole ; Spinal Cord

BACKGROUND: The evidence for increased oxidative stress and DNA damage in amyotrophic lateral sclerosis (ALS) prompted studies to determine if the expression of poly (ADP-ribose) polymerase (PARP) is increased in ALS. METHOD: Twenty Spinal cord specimens were obtained at the autopsy of sALS patients (n=11) and age-matched controls with non-neurological diseases (n=9). RESULTS: Using western analyses of postmortem tissue, we demonstrated that PARP-immunoreactivity (PARP-IR) was increased three-fold in spinal cord tissues of sporadic ALS (sALS) patients compared with non-neurological disease controls. Despite the increased PARP-IR, PARP mRNA expression was not increased significantly. Immunohistochemical analyses revealed PARP-IR was increased in both white and gray matter of sALS spinal cord. While PARP-IR was predominantly seen in astrocytes, large motor neurons displayed reduced staining compared with the controls. PARP-IR was increased in the pellet fraction of sALS homogenates compared with the control homogenates, representing potential PARP binding to chromatin or membranes and suggesting a possible mechanism of PARP stabilization. CONCLUSIONS: The present results demonstrate glial alterations in sALS tissue and support the role of glial alterations in sALS pathogenesis.
Amyotrophic Lateral Sclerosis* ; Astrocytes* ; Autopsy ; Chromatin ; DNA Damage ; Humans ; Membranes ; Motor Neurons* ; Oxidative Stress ; RNA, Messenger ; Spinal Cord*