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Signalling pathways associated with 5-HT6 receptors: relevance for cognitive effects

  • Beatriz Marcos (a1), Maria Cabero (a1), Maite Solas (a1), Bárbara Aisa (a1) and Maria J. Ramirez (a1)...

A growing body of evidence supports the use of serotonin 5-HT6 receptor antagonists as a promising mechanism for treating cognitive dysfunction. We evaluated 5-HT6 receptor expression and associated biochemical mechanisms in the hippocampus of rats that had been trained in the Morris water maze (MWM), a spatial learning task. Training in the MWM induces a down-regulation of 5-HT6 receptor protein and mRNA receptor expression. The learning procedure or the administration of the selective 5-HT6 receptor antagonist SB-271046 induced an increase in pCREB1 levels while CREB2 levels were significantly reduced. However, although SB-271046 was able to improve retention in the MWM, no further changes in pCREB1 or CREB2 levels were found to be associated with the presence of the 5-HT6 receptor antagonist during the learning procedure. The MWM procedure significantly increased pERK1/2 levels and interestingly, further increases were seen when treating with SB-271046 during the MWM. These results suggest that, in the hippocampus, biochemical pathways associated with pERK1/2 expression, and not with the CREB family of transcription factors, seem to be related to the cognitive-enhancing properties of 5-HT6 receptor antagonists.

Corresponding author
Address for correspondence: Dr M. J. Ramírez, Department of Pharmacology, School of Medicine, University of Navarra, Irunlarrea 1, 31008Pamplona, Spain. Tel.: +34 948425600Fax: +34 948425649Email:
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