Repeated stress increases catalytic TrkB mRNA in rat hippocampus

Northern blot analysis was utilized to distinguish between catalytic and tr uncated TrkB mRNA on the basis of transcript size. Repeated (10 days), but not acute, immobilization stress significantly increased levels of catalyti c TrkB mRNA, but did not influence expression of truncated TrkB transcripts in rat hippocampus. Exposure to another paradigm, a combination of differe nt, unpredictable stressors, also increased levels of catalytic, but not tr uncated, TrkB mRNA. In situ hybridization analysis demonstrated that chroni c stress up-regulated TrkB mRNA in CA1 and CA3 pyramidal and dentate gyrus granule cells layers of hippocampus. As previously reported, both acute and chronic immobilization stress decreased expression of BDNF mRNA, suggestin g that up-regulation of catalytic TrkB mRNA may be a compensatory adaptatio n to repeated stress. (C) 1999 Elsevier Science Ireland Ltd. All rights res erved.