BDNF and injury: Approximately 1–6 h after traumatic brain injury, BDNF level reportedly increased maximally in the ipsilesional hippocampus (43), whereas Matzilevich et al. (57) found increased BDNF expression at 26 h after brain trauma, and the increase in BDNF mRNA expression in the hippocampus can be sustained for 2 weeks after injury, as reported previously (44).