Molecular and Chemical Neuropathology

, Volume 31, Issue 3, pp 225–233 | Cite as

Downregulation of brain-derived neurotrophic factor mRNA in adult rat brain after acute administration of methylmercury

  • Helena AnderssonEmail author
  • Eva Lindqvist
  • Lars Olson
Original Articles


Conventionally, assessment of the neurotoxicity of environmental pollutants relies on high-dosage treatment and nonspecific end points. In the present study, the early temporal and regional alterations in the mRNAs of neurotrophins were investigated following subtoxic doses of methylmercury (MeHg) in adult Sprague-Dawley rats usingin situ hybridization histochemistry and phosphoimaging evaluation. Decreases in brain-derived neurotrophic (BDNF) mRNA labeling intensities were seen in the dentate gyrus (DG; 44% of controls), and in the CA1 (72% of controls) and CA3c (70% of controls) cell layers of hippocampus after 8 mg MeHg/kg (ip) at 4 h, and at 1 h only in the DG. The decrease in BDNF mRNA expression in the DG was dose-dependent. At 3 d, regional levels had recovered. No significant changes could be detected in mRNA levels of the BDNF high-affinity receptor trkB or neurotrophin-3 mRNA at either 1 h, 4 h, or 3 d. Cresyl violet staining and GFAP immunohistochemistry did not reveal any major neuropathology in hippocampus at 2 wk. Thus, MeHg causes specific downregulation of BDNF mRNA, unlike many other perturbations of central nervous system homeostasis that have been shown to lead to upregulation of this mRNA.

Index Entries

Methylmercury neurotoxicity hippocampus brain-derived neurotrophic factor neurotrophin-3 


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Copyright information

© Humana Press Inc 1997

Authors and Affiliations

  1. 1.Department of NeuroscienceKarolinska InstituteStockholmSweden

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