Abstract
Aims: Rutin is one of the flavonoids that has many beneficial effects on the health. Previously, we showed that rutin has a protective effect on trimethyltin (TMT)-induced memory dysfunction in rats. The aim of this study was to investigate the protective effects of rutin on TMT-induced hippocampal injury and the time course profiles of these effects in rats. Methods: Four-week-old male Sprague-Dawley (SD) rats were fed chow with or without rutin (0.75%) during the experimental period and were administered with a single dose of TMT (8.5 mg/kg b.w., p.o.) or vehicle at 6 weeks of age. The rats were sacrificed 5, 10, or 20 days after the TMT administration and then histological and molecular examinations of the hippocampus were performed. Results: Rutin supplementation suppressed the TMT-induced decrease in the number of hippocampal pyramidal neurons 20 days after TMT administration. The TMT-induced up-regulation of the mRNA expression levels of reactive microglia marker and pro-inflammatory cytokines were reversed by rutin supplementation 10 or 20 days after the TMT administration. Conclusions: These results suggested that the neuroprotective effect of rutin on TMT-induced spatial memory impairment could be attributable to its inhibitory effect against microglial activation and its role in synapse formation via neurotrophic factors in the hippocampus.