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Paradoxical increase in survival of newborn neurons in the dentate gyrus of mice with constitutive depletion of serotonin


Diaz, Silvina L; Narboux-Nême, Nicolas; Trowbridge, Sara; Scotto-Lomassese, Sophie; Kleine Borgmann, Felix B; Jessberger, Sebastian; Giros, Bruno; Maroteaux, Luc; Deneris, Evan; Gaspar, Patricia (2013). Paradoxical increase in survival of newborn neurons in the dentate gyrus of mice with constitutive depletion of serotonin. European Journal of Neuroscience, 38(5):2650-2658.

Abstract

Increased adult neurogenesis is a major neurobiological correlate of the beneficial effects of antidepressants. Indeed, selective serotonin (5-HT) re-uptake inhibitors, which increase 5-HT transmission, enhance adult neurogenesis in the dentate gyrus (DG) of the hippocampus. However, the consequences of 5-HT depletion are still unclear as studies using neurotoxins that target serotonergic neurons reached contradictory conclusions on the role of 5-HT on DG cell proliferation. Here, we analysed two genetic models of 5-HT depletion, the Pet1(-/-) and the VMAT2(f/f) ; SERT(cre/+) mice, which have, respectively, 80 and 95% reductions in hippocampal 5-HT. In both models, we found unchanged cell proliferation of the neural precursors in the DG subgranular zone, whereas a significant increase in the survival of newborn neurons was noted 1 and 4 weeks after BrdU injections. This pro-survival trait was phenocopied pharmacologically with 5-HT synthesis inhibitor PCPA treatment in adults, indicating that this effect was not developmental. Furthermore, a 1-week administration of the 5-HT1A receptor agonist 8-OH-DPAT in Pet1(-/-) and PCPA-treated mice normalised hippocampal cell survival. Overall, our results indicate that constitutive 5-HT depletion does not alter the proliferation of neural precursors in the DG but promotes the survival of newborn cells, an effect which involves activation of postsynaptic 5-HT1A receptors. The role of 5-HT in selective neuronal elimination points to a new facet in its multiple effects in controlling neural circuit maturation.

Abstract

Increased adult neurogenesis is a major neurobiological correlate of the beneficial effects of antidepressants. Indeed, selective serotonin (5-HT) re-uptake inhibitors, which increase 5-HT transmission, enhance adult neurogenesis in the dentate gyrus (DG) of the hippocampus. However, the consequences of 5-HT depletion are still unclear as studies using neurotoxins that target serotonergic neurons reached contradictory conclusions on the role of 5-HT on DG cell proliferation. Here, we analysed two genetic models of 5-HT depletion, the Pet1(-/-) and the VMAT2(f/f) ; SERT(cre/+) mice, which have, respectively, 80 and 95% reductions in hippocampal 5-HT. In both models, we found unchanged cell proliferation of the neural precursors in the DG subgranular zone, whereas a significant increase in the survival of newborn neurons was noted 1 and 4 weeks after BrdU injections. This pro-survival trait was phenocopied pharmacologically with 5-HT synthesis inhibitor PCPA treatment in adults, indicating that this effect was not developmental. Furthermore, a 1-week administration of the 5-HT1A receptor agonist 8-OH-DPAT in Pet1(-/-) and PCPA-treated mice normalised hippocampal cell survival. Overall, our results indicate that constitutive 5-HT depletion does not alter the proliferation of neural precursors in the DG but promotes the survival of newborn cells, an effect which involves activation of postsynaptic 5-HT1A receptors. The role of 5-HT in selective neuronal elimination points to a new facet in its multiple effects in controlling neural circuit maturation.

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18 citations in Web of Science®
20 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Brain Research Institute
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2013
Deposited On:12 Dec 2013 08:34
Last Modified:05 Apr 2016 17:14
Publisher:Wiley-Blackwell
ISSN:0953-816X
Publisher DOI:https://doi.org/10.1111/ejn.12297
PubMed ID:23841816

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