Chronic immobilization stress differentially affects the expression of BDNF mRNA and protein in the mouse hippocampus

Abstract

AbstractStress impacts multiple systems within the CNS, including the hippocampus. A key molecular mediator in hippocampal functions, including learning and memory, is brain‐derived neurotrophic factor (BDNF). BDNF mRNA is reported to be decreased following chronic (every day) immobilization stress (CIS) in the rat, however the effect on protein is unknown. Utilizing a mouse model of CIS, the hypothesis that total hippocampal BDNF protein, in addition to BDNF mRNA, would be decreased was tested. The effects of intermittent (alternating day) immobilization and cold stress on hippocampal BDNF protein levels was also examined.In this study it was demonstrated that CIS results in a small (8 per cent decrease relative to non‐stressed controls), but significant (p = 0.0013) decrease in the exon coding for mature BDNF (exon VI). In addition, there was a significant (34 per cent, p = 0.005) decrease in the mRNA coding for exon I in the stressed animals. Contrary to expectations, however, CIS resulted in a significant (116 per cent, p = 0.0087) increase in hippocampal BDNF protein levels. Furthermore, both intermittent immobilization and chronic cold stress both increased BDNF protein levels. Chronic stress, therefore, differentially regulates BDNF mRNA and protein levels in the hippocampus. Copyright © 2004 John Wiley & Sons, Ltd.