Effects of trimethyltin on incremental repeated acquisition (learning) in the rat.

The effects of the neurotoxicant, trimethyltin (TMT), on the acquisition of serial position response chains (learning) in adult rats were examined. Animals performing incremental repeated acquisition tasks for food were injected once with either 7.5 or 8.7 mg/kg TMT, IP. TMT decreased efficiencies (correct/total responses) in all 5 subjects; maximal decrements occurred 1-3 weeks post-treatment. Efficiency in 3 rats returned to pre-TMT levels within 5 weeks; values for the other 2 animals did not return in 3 months. Errors were markedly increased 1-2 weeks post-treatment in 4/5 subjects. Response rates increased for 2 animals within a week of TMT treatment and remained elevated for 5 weeks. Sustained rate increases occurred for 2 other animals 4-5 weeks after treatment. Thus, TMT effects on various aspects of incremental repeated acquisition behavior follow different time-courses.