Title

Exposure to depressant drugs leads to neuronal death within the developing piriform cortex

Authors

Shannon Klebe

Document Type

Article

Publication Date

2006

Abstract

Ethanol and other sedative hypnotic drugs are known to have deleterious effects within developing brains. Previous research has demonstrated, using post-natal day 14 (PND 14) rats, that a single exposure to urethane, an anesthetic once used in humans, can cause selective death within the piriform cortex. This project characterized the mode of neuronal death within this region, after administering the anesthetic urethane and anxiolytic Valium, given at PND 14. Half of the rats were perfused 24 hours after injection, the other half at 48 hours. One hemisphere was used for transmission electron microscopy (TEM), and the other hemisphere was cut into 40? and 20? sections that were used for immunohistochemistry (which allowed us to assay for apoptosis-related molecules) and H & E staining (which identifies dying cells), respectively. Immunofluorescence and immunoperoxidase detected the presence of active caspase 3 and apoptosis inducing factor (AIF) within the piriform cortices of experimental and control animals. The expression of these molecules indicates a cell undergoing apoptosis, otherwise known as cell suicide. The number of cells positive for each of these proteins was low in experimental animals, highest in the 24 hour group, and still obvious in the 48 hour group. These findings were consistent with cell counts obtained from the H and E stain. Because the ultrastructure of a dying cell is definitive of either apoptosis or necrosis, TEM allowed us to confirm the mode of neuronal death. We visualized cells undergoing both forms of degeneration, suggesting that sedative hypnotics can simultaneously activate each distinct pathway in developing brains.

Advisor

Kerry Thompson, Gary Martin

Department

bio

Support

Sherman Fairchild Foundation Grant

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