Effects of trimethyltin on evoked potentials in mouse hippocampal slices

The effects of trimethyltin (TMT) on responses to orthodromic stimulation in the CA1 pyramidal cell layer and dentate gyrus were investigated in mouse hippocampal slices. In both regions exposure to 10.0 microM TMT produced an 80 to 90% reduction in population spike amplitude. Smaller decreases in spike amplitude occurred after 5 microM TMT and these effects were reversible in the pyramidial cell layer. The latency of 5.0 microM effects was longer in the dentate gyrus and were preceded by a slight (20%) increase in spike amplitude. The smallest dose of TMT tested (1.0 microM) did not change response amplitude, but did increase the occurrence of multiple population spike potentials. When TMT was applied during paired-pulse stimulation of the perforant path the potentiation of the second response was not selectively reduced. The results indicate that orthodromic excitability of both pyramidal and granule cells in the mouse hippocampus is decreased by TMT with small differences occurring in latency and reversibility at certain doses.