Dietary and Intraperitoneal Administration of Selenium Provide Comparable Protection in the 6-Hydroxydopamine Lesion Rat Model of Parkinson's Disease

Moravian College

Month 2

Significant research implicates the involvement of free radicals in the manifestation of Parkinson's disease. The antioxidant, selenium is a vital dietary component for mammals. It is present in the active center of glutathione peroxidase, an antioxidant enzyme that scavenges peroxides and protects membrane lipids and macromolecules from oxidative insult. The purpose of this research was to determine an effective means of delivering selenium as well as an appropriate time frame for antioxidant administration that would elicit a protective response in rats challenged with an intranigral 6-hydroxydopamine (6-OHDA) lesion. In the first part of this study, Fischer 344 rats were placed into one of four groups: selenium enhanced diet, control diet, intraperitoneal injection of selenium as Na2SeO3 or intraperitoneal injection of distilled water. All treatments were delivered prior to an intranigral 6-OHDA lesion. Animals were euthanized two weeks post lesion and their brains processed for tyrosine hydroxylase (TH) immunocytochemistry. Average dopamine neuron survival in the substantia nigra of control animals was less than 22%; whereas nigral dopamine neuron survival in the selenium fed group was 49.7% and 56.0% in the selenium injected group. Based on these results, a subsequent study was designed utilizing the selenium enhanced diet method of antioxidant administration. To examine the neuroprotective effect of long-term selenium treatment, pregnant Fischer 344 rats were exposed to either selenium enhanced or control rat chow. Their pups were treated with the same diet as their mothers and lesioned with 6-OHDA at two months of age. Animals were euthanized and their brains were processed for TH immunocytochemistry. Nigral dopamine neuron survival for the selenium treated animals was significantly protective (59%) when compared to the control chow fed animals (29.6%). However, when compared to the short-term exposure of selenium rat chow in the previous study, there was no significant increase in neuroprotection.

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