Objective Exposure to a number of drugs, chemicals or environmental factors can cause parkinsonism. Epidemiologic evidence supports a causal link between the consumption of flour made from the washed seeds of the plant, Cycas micronesica, by the Chamorro population of Guam and the development of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC). Methods We now report that consumption of washed cycad flour pellets by Sprague-Dawley male rats induces progressive parkinsonism. Results Cycad-fed rats displayed motor abnormalities after two to three months of feeding such as spontaneous unilateral rotation, shuffling gait and stereotypy. Histological and biochemical examination of brains from cycad-fed rats revealed an initial decrease in the levels of dopamine and its metabolites in the striatum (STR), followed by neurodegeneration of dopaminergic (DAergic) cell bodies in the substantia nigra pars compacta (SNc). α-synuclein (α-syn; proteinase K-resistant) and ubiquitin aggregates were found in the DAergic neurons of the SNc and neurites in the STR. In addition, we identified α-syn aggregates in neurons of the locus coeruleus and cingulate cortex. No loss of motor neurons in the spinal cord was found after chronic consumption of cycad flour. In an organotypic slice culture of the rat substantia nigra and the striatum, an organic extract of cycad causes a selective loss of DA neurons and α-synuclein aggregates in the substantia nigra. Interpretation Cycad-fed rats exhibit progressive behavioral, biochemical, and histological hallmarks of parkinsonism, coupled with a lack of fatality.

BackgroundAge is considered a primary risk factor for neurodegenerative diseases including Alzheimer’s disease (AD). It is also now well understood that mitochondrial function declines with age. Mitochondrial deficits have been previously assessed in brain from both human autopsy tissue and disease-relevant transgenic mice. Recently it has been recognized that abnormalities of muscle may be an intrinsic aspect of AD and might contribute to the pathophysiology. However, deficits in mitochondrial function have yet to be clearly assessed in tissues outside the central nervous system (CNS). In the present study, we utilized a well-characterized AD-relevant transgenic mouse strain to assess mitochondrial respiratory deficits in both brain and muscle. In addition to mitochondrial function, we assessed levels of transgene-derived amyloid precursor protein (APP) in homogenates isolated from brain and muscle of these AD-relevant animals.ResultsWe now demonstrate that skeletal muscles isolated from these animals have differential levels of mutant full-length APP depending on muscle type. Additionally, isolated muscle fibers from young transgenic mice (3 months) have significantly decreased maximal mitochondrial oxygen consumption capacity compared to non-transgenic, age-matched mice, with similar deficits to those previously described in brain.ConclusionsThis is the first study to directly examine mitochondrial function in skeletal muscle from an AD-relevant transgenic murine model. As with brain, these deficits in muscle are an early event, occurring prior to appearance of amyloid plaques.

Vacuolation in cellular organelles within the central nervous system is a common manifestation of oxidative injury. We found that the spongiform vacuolation observed in PVC-211 murine leukemia virus (PVC-MuLV) neurodegeneration was associated with oxidative damage as detected by immunoreactivity for 3-nitrotyrosine and protein carbonyl groups. This oxidative injury was present in brain before or concomitant with the appearance of activated microglia, vacuolation, and gliosis that characterize PVC-MuLV neuropathology. Treatment of infected F344 rat pups with the antioxidant vitamin E transiently protected and prolonged the latency of PVC-MuLV neurodegeneration. Taken together, these findings implicate oxidative damage and lipid peroxidation in the pathogenesis of PVC-MuLV neurodegeneration. This animal model may be useful for studies of mechanisms and potential therapies for progressive neurodegeneration following a well-defined insult.

Vacuolation in cellular organelles within the central nervous system is a common manifestation of oxidative injury. We found that the spongiform vacuolation observed in PVC‐211 murine leukemia virus (PVC‐MuLV) neurodegeneration was associated with oxidative damage as detected by immunoreactivity for 3‐nitrotyrosine and protein carbonyl groups. This oxidative injury was present in brain before or concomitant with the appearance of activated microglia, vacuolation, and gliosis that characterize PVC‐MuLV neuropathology. Treatment of infected F344 rat pups with the antioxidant vitamin E transiently protected and prolonged the latency of PVC‐MuLV neurodegeneration. Taken together, these findings implicate oxidative damage and lipid peroxidation in the pathogenesis of PVC‐MuLV neurodegeneration. This animal model may be useful for studies of mechanisms and potential therapies for progressive neurodegeneration following a well‐defined insult. J. Neurosci. Res. 62:440–450, 2000. Published 2000 Wiley‐Liss, Inc.

PVC-211 murine leukemia virus (MuLV) is a neuropathogenic variant of Friend MuLV (F-MuLV