Acute trimethyltin exposure produces nonspecific effects on learning in rats working under a multiple repeated...

Previous research has explored the adverse effects of trimethyltin (TMT) on learning and memory in laboratory animals. Virtually all studies of TMT effects on learning have not, however, included appropriate controls to establish a selective effect on learning. This experiment investigated the effects of TMT on the repeated acquisition (learning) and performance of response sequences. Adult male Long-Evans rats, maintained at 300 g b.wt., were trained with food reinforcement under a multiple repeated acquisition (RA) and performance (P) schedule. The RA component required rats to learn a different three-member response sequence during each session (Center Right Left, RLC, RCL, LCR, or LRC); the correct response sequence remained constant in the P component (CLR). RA and P components alternated twice during a session. Rats were given 0, 4, or 8 mg/kg TMT IV after 30 sessions of stable baseline performance, and an additional 40 sessions were conducted following TMT. Prior to TMT, all groups maintained comparable accuracy levels in both RA and P components. Following TMT, significant decreases in both accuracy and response rate were obtained in the 8 mg/kg group. Thereafter, response rate and accuracy both recovered to near baseline levels, although large individual differences were observed. No selective effects of TMT were obtained on RA when compared to P. These data suggest that TMT-induced impairments on learning may be due to a generalized performance decrement rather than a specific effect on learning.