Synergistic actions of corticosterone and BDNF on rat hippocampal LTP.

Exercise evokes many physiological changes, including the release of hormones and growth factors that are known to improve cognition via unknown mechanisms. Here, we have compared the ability of two physiologically relevant factors, corticosterone (CORT) and brain-derived neurotrophic factor (BDNF), to affect long-term potentiation (LTP) in the hippocampus. Using a compressed theta-burst stimulation (cTBS) protocol, we found that CORT has no effect on LTP, BDNF enhances LTP and combined CORT + BDNF treatment results in significantly greater LTP. We also find that CORT + BDNF, but not either compound alone, results in phosphorylation of protein kinase A (PKA). These findings show that BDNF and CORT act synergistically to enhance LTP at these synapses, potentially via a PKA-dependent mechanism. Such a synergistic action could underlie the positive cognitive effects of exercise.