Correlation between hippocampal BDNF mRNA expression and memory performance in senescent rats

Brain-derived neurotrophic factor (BDNF) has been suggested to be involved in memory processes. In the present study, the association between memory impairment at senescence and BDNF expression in the hippocampus was studied in 30-32-month-old Brown Norway rats, which had been maternally deprived early in life. These animals display a bimodal distribution in their spatial learning ability: rats are either non-impaired or impaired. BDNF mRNA expression in the hippocampus was compared between non-impaired and impaired rats. We measured BDNF mRNA expression in the hippocampus 3 h after training in the Morris water maze ('post-training') and at 1 month after training ('basal'). Non-impaired performers displayed a higher post-training BDNF mRNA level in the CA1 region than impaired rats. In addition, only in the non-impaired performers post-training BDNF mRNA levels in CA1 and dentate gyrus were increased as compared to basal levels. Thus, we have demonstrated that in senescent rats, hippocampal BDNF expression in response to water maze training is associated with memory performance.