Effects of Swimming Training on Learning and Memory Impairment Induced by Trimethyltin Chloride in BALB/c Mice

Objectives To explore the effects and mechanism of swimming training on learning and memory impairment induced by trimethyltin chloride (TMT) in BALB/c mice.

Methods 6~9 week-old BALB/c mice were randomly divided into 4 groups: saline group, TMT group, saline +swimming training group (saline+ST), and TMT+swimming training group (TMT+ST). There were 20 rats each in saline group and TMT group and 10 rats each in the other two groups. Equal volume of normal saline solution or TMT (2.25 mg/kg·BW) in normal saline solution were injected intraperitonealy after an adaptation to the laboratory for one week. Swimming training was conducted daily for 7 days started from 24 h after the injection of TMT or saline. Morris water maze (latency escape) for testing the learning and memory ability, and western blot for analyzing growth associated protein (GAP-43) and synaptophysin (SYP) in the hippocampus of mice were conducted at 24 h and in the 8th day after the injection of TMT or saline.

Results Comparing with the saline group, the latency escape was significantly prolonged (P < 0.05) in TMT group at 24 h and in the 8 th day after the administration of TMT. Comparing with the saline group and saline+ST group, the latency escape in TMT+ST group was not significantly different (P > 0.05) after the injection of TMT for 7 days. Comparing with the saline group, the expression of SYP decreased (P < 0.05) in hippocampus in the TMT group after injection for 24 h, and the expression of GAP-43 in hippocampus in TMT group showed no statistical significance (P > 0.05). Comparing with the TMT group, the expression of GAP-43 and SYP in the hippocampus of TMT+ST group increased (P < 0.05) after the injection of TMT for 7 days; while comparing with the saline group and saline+ST group, the expression of GAP-43 and SYP in hippocampus in TMT+ST group was not statistically different (P > 0.05).

Conclusions The learning and memory ability of mice impaired by TMT could be improved by swimming training, and its potential mechanism might be related to the increased expression of SYP and GAP-43 in hippocampus.