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Trimethyltin increases choline acetyltransferase in rat hippocampus
R L Cannon1, D B Hoover, M L Woodruff
1Department of Anatomy, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614.
Neurotoxicology and Teratology
|March 1, 1991
Summary
Trimethyltin (TMT) exposure causes increased choline acetyltransferase activity in the hippocampus, suggesting reactive synaptogenesis in the septohippocampal system. This neurotoxin damages brain regions but spares cholinergic projections.
Area of Science:
- Neuroscience
- Toxicology
- Neurobiology
Background:
- The environmental neurotoxin trimethyltin (TMT) is known to cause damage to the hippocampal formation and entorhinal cortex.
- The septal cholinergic projection to the hippocampus and dentate gyrus remains intact following TMT exposure.
Purpose of the Study:
- To investigate the effects of TMT exposure on cholinergic innervation density in specific brain regions.
- To determine if TMT exposure induces changes in choline acetyltransferase (ChAT) activity, a marker for cholinergic neurons.
Main Methods:
- Rats were exposed to a single dose of TMT (7 mg/kg) via gastric intubation.
- Choline acetyltransferase (ChAT) activity was measured in micropunch samples of the dentate gyrus, CA1 region, and caudate-putamen three months post-exposure.
- ChAT activity in TMT-exposed rats was compared to control rats.
Main Results:
- Significantly higher ChAT activity was observed in the dentate gyrus and CA1 region of TMT-exposed rats compared to controls.
- No significant differences in ChAT activity were found in the caudate-putamen between the groups.
- These findings indicate an increase in cholinergic innervation density in specific hippocampal subfields.
Conclusions:
- Exposure to trimethyltin (TMT) leads to reactive synaptogenesis within the cholinergic septohippocampal system.
- The hippocampus exhibits compensatory mechanisms in response to TMT-induced neurotoxicity.
- These results contribute to understanding the long-term neurobiological consequences of TMT exposure.