RESUMEN
Parkinson's disease is the second most important neurodegenerative disorder worldwide. It is characterized by the presence of Lewy bodies, which are mainly composed of α-synuclein and ubiquitin-bound proteins. Both the ubiquitin proteasome system (UPS) and autophagy-lysosomal pathway (ALS) are altered in Parkinson's disease, leading to aggregation of proteins, particularly α-synuclein. Interestingly, it has been observed that copper promotes the protein aggregation process. Additionally, phosphorylation of α-synuclein along with copper also affects the protein aggregation process. The interrelation among α-synuclein phosphorylation and its capability to interact with copper, with the subsequent disruption of the protein degradation systems in the neurodegenerative process of Parkinson's disease, will be analyzed in detail in this review.
RESUMEN
The accidental ingestion of Karwinskia humboldtiana (Kh) fruit in humans and animals causes chronic or acute intoxication. Acute poisoning induces respiratory failure that progresses rapidly to death. Studies in animals intoxicated with Kh describe lesions in cerebral cortex, cerebellum, spinal cord, hippocampus and caudate nucleus. Kh intoxication in Wistar rats models the sub-lethal clinical phase observed in humans. Considering these reports, the present study analyzed the histopathological alterations within the striatum following experimental Kh intoxication. Twenty Wistar rats were divided into three groups (n =5) and were intoxicated with Kh fruit. A control group (n =5) was included. Animals were euthanized at several time points (48, 58 and 170 days post-intoxication). The brain was collected, divided and processed for conventional histology or electron microscopy. Sections were stained with hematoxylin and eosin, cresyl violet, Klüver-Barrera, and toluidine blue. Immunolabeling was performed for glial cells in the striatum, and the samples were analyzed with light microscopy. Morphometric and statistical analyses were performed. In control group, neurons, axon bundles and neuropil had a normal appearance. At 48 days, hyperchromic neurons with apparent decreased size were observed interspersed among the normal neurons. At 58 days, we observed an increased number of hyperchromic neurons and disorganization of the myelin sheath and neuropil. At 170 days, these alterations persisted in the paralysis group. In treated groups, we observed signs of gliosis and increased axonal diameters. This study is the first report that describes the histopathological alterations within the striatum caused by chronic intoxication with Kh fruit in the Wistar rat.
