Ibotenic acid in the medial septum increased brain-derived neurotrophic factor mRNA levels in the dorsal rat hippocampal formation.

Excitotoxic lesion of the medial septum with ibotenic acid leading to partial disappearance of the septal cholinergic nerve cells was used to investigate the role of cholinergic mechanisms in the control of trophic factors for hippocampal plasticity, namely brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor (GR). Their mRNA levels were tested by in situ hybridization 13 days after the lesion. A persistent and widespread increase of BDNF mRNA was found in all parts of the dorsal hippocampal formation that was not accompanied by a significant modification in GR expression. The present data suggest that subcortical excitotoxic lesions at the septal level have long-term consequences for the adaptive trophic responses occurring in the dorsal hippocampus.