Glucocorticoids modulate BDNF mRNA expression in the rat hippocampus aftertraumatic brain injury

Brain-derived neurotrophic factor (BDNF) expression in rat hippocampus is i ncreased after experimental traumatic brain injury (TBI) and may be neuropr otective. Glucocorticoids are important regulators of brain neurotrophin le vels and are often prescribed following TBI. The effect of adrenalectomy (A DX) on the expression of BDNF mRNA in the hippocampus after TBI has not bee n investigated to date. We used fluid percussion injury (FPI) and in situ h ybridization to evaluate the expression of BDNF mRNA in the hippocampus 4 h after TBI in adrenal-intact or adrenalectomized rats (with or without cort icosterone replacement). FPI and ADX independently increased expression of BDNF mRNA. In animals undergoing FPI, prior ADX caused further elevation of BDNF mRNA and this upregulation was prevented by corticosterone replacemen t in ADX rats. These findings suggest that glucocorticoids are involved in the modulation of the BDNF mRNA response to TBI. NeuroReport 11:3381-3384 ( C) 2000 Lippincott Williams & Wilkins.