Down-regulation of BDNF mRNA, with no effect on trkB or glucocorticoid receptor mRNAs, in the porcine hippocampus after acute dexamethasone treatment

Glucocorticoids bind to hippocampal mineralo-(MR) and gluco-(GR) corticoid receptors and, at high concentrations (e.g. as seen following treatment wit h pharmacological doses of corticosteroids or during stress), may affect hi ppocampal neuronal function. Such actions could involve brain-derived neuro trophic factor (BDNF), its receptor, trkB, and the excitatory neurotransmit ter, glutamate. This experiment investigated the effect of a single intrave nous (i.v.) injection of the synthetic glucocorticoid, dexamethasone (Dex, 5 mg kg(-1)) on gene expression for MRS, GRS, BDNF, trkB, and selected iono tropic glutamate receptor subunits (iGluRs), in the porcine hippocampus. Qu antification of mRNAs in the brains of pigs (n = 4/treatment) killed 24 hou rs after saline or Dex administration indicated a significant Dex-induced d ecrease in BDNF mRNA in all hippocampal regions. However, gene expression f or MRS, GRS, trkB and iGluRs was unaffected at this time-point. (C) 2001 Ha rcourt Publishers Ltd.