Chemically Induced Damage to the Hippocampal Formation,
Abstract
In the present work it was shown that degeneration of the hippocampal formation after trimethyltin (TMT) administration can be detected at an early phase by eletric recordings from intrahippocampal electrodes. The anatomical distribution of the damage can be studied by histochemistry, and was shown to include the CA3 and CA4 subfields in the initial period and spreading to the CA1 after a complete destruction of the pyramidal cells in CA3 and CA4. The degeneration was shown to be specific for glutamergic neurons in the hippocampus, high affinity uptake of Hydrogen3 glutamate being only biochemical parameter which was changed. In vitro TMT increased the efflux of Hydrogen3 glutamate from synaptosomes in the resting state, but had no effect on the efflux of Hydrogen3 GABA. The synaptosomal reuptake of transmitter and receptor binding were both inhibited in the presence of TMT. In relation to reports on TMT as an anion conductor, the effect of changes in extracellular C1 concentration on transmitter release was investigated. A reduction in the external C1 concentration was shown to have a much larger effect on the efflux of transmitter frm glutamergic than from GABAergic synaptosomes. The sensitivity of the hippocampal electric activity to changes after exposure to toxic compounds was utilized for the investigation of a putative neurotoxic effect of long term exposure to low levels of toluene. No improvements regarding regularity or freuency was seen during one month after termination of exposure, indicating that irreversible changes in neuronal functions have occured.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1986
- Accession Number
- ADA168096
Entities
People
- Liv U. Naalsund
Organizations
- Norwegian Defence Research Establishment