Journal Article

Reduction of Glutamatergic Neurotransmission by Prolonged Exposure to Dieldrin Involves NMDA Receptor Internalization and Metabotropic Glutamate Receptor 5 Downregulation

Victor Briz, Mireia Galofré and Cristina Suñol

in Toxicological Sciences

Volume 113, issue 1, pages 138-149
Published in print January 2010 | ISSN: 1096-6080
Published online October 2009 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/kfp244
Reduction of Glutamatergic Neurotransmission by Prolonged Exposure to Dieldrin Involves NMDA Receptor Internalization and Metabotropic Glutamate Receptor 5 Downregulation

More Like This

Show all results sharing these subjects:

  • Medical Toxicology
  • Toxicology (Non-medical)

GO

Show Summary Details

Preview

Dieldrin was previously used as a pesticide. Although its use has been discontinued, humans are still exposed to it due to its high environmental persistence and because it accumulates in the adipose tissue of animals. Acute exposure to dieldrin provokes convulsions due to its antagonism on the gamma-aminobutyric acid-A (GABAA) receptor. However, little is known about the effects of low chronic exposure to this pollutant. In the present work, we use primary cultures of cortical neurons to study the mechanisms involved in the toxic action of dieldrin. We found that 2 and 6 days in vitro (DIV) exposure to a subcytotoxic concentration (60nM) of dieldrin reduced the increase in intracellular calcium concentration ([Ca2+]i) and the excitotoxicity caused by glutamate. Exposure to dieldrin for 6 DIV induced N-methyl-D-aspartate receptor (NMDAR) internalization and reduced metabotropic glutamate receptor 5 (mGLUR5) levels. Double immunostaining for NMDAR and mGLUR5 showed that these receptors lose colocalization on the cell membrane in neurons treated with dieldrin. No changes were observed in receptor functionalities or receptor levels after 2 DIV of exposure to dieldrin. However, the increase in [Ca2+]i induced by coactivation of NMDAR and mGLUR5 was significantly reduced. Thus, a functional interaction between the two receptors seems to play an important role in glutamate-induced excitotoxicity. We confirm that permanent blockade of the GABAA receptor by this persistent pesticide triggers adaptive neuronal changes consisting of a reduction of glutamatergic neurotransmission. This might explain the cognitive and learning deficits observed in animals after chronic treatment with dieldrin.

Keywords: dieldrin; neurotoxicity; in vitro; glutamate; receptor

Journal Article.  7549 words.  Illustrated.

Subjects: Medical Toxicology ; Toxicology (Non-medical)

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.