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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Pharmacol. | doi: 10.3389/fphar.2019.01000

Salmeterol, a β2 adrenergic agonist, promotes adult hippocampal neurogenesis in a region-specific manner

 Valeria Bortolotto1,  Heather Bondi1, Bruna Cuccurazzu1, Maurizio Rinaldi1, Pier Luigi Canonico1 and  Mariagrazia Grilli1*
  • 1Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale, Italy

Neurogenesis persists in the subgranular zone of the hippocampal formation in the adult mammalian brain. In this area, neural progenitor cells (NPCs) receive both permissive and instructive signals, including neurotransmitters, that allow them to generate adult-born neurons which can be functionally integrated in the preexisting circuit. Deregulation of adult hippocampal neurogenesis (ahNG) occurs in several neuropsychiatric and neurodegenerative diseases, including major depression, and represents a potential therapeutic target. Of interest, several studies suggested that, both in rodents and in humans, ahNG is increased by chronic administration of classical monoaminergic antidepressant drugs, suggesting that modulation of this process may participate to their therapeutic effects. Since the established observation that noradrenergic innervations from locus coeruleus make contact with NPC in the dentate gyrus, we investigated the role of beta adrenergic receptor (b-AR) on ahNG both in vitro and in vivo. Here we report that, in vitro, activation of b2-AR by norepinephrine and b2-AR agonists promotes the formation of NPC-derived mature neurons, without affecting NPC survival or differentiation toward glial lineages. Additionally, we show that a selective b2-AR agonist able to cross the blood brain barrier, salmeterol, positively modulates hippocampal neuroplasticity when chronically administered in adult naïve mice. Indeed salmeterol significantly increased number, maturation and dendritic complexity of DCX+ neuroblasts. The increased number of DCX+ cells was not accompanied by a parallel increase in the percentage of BrdU+/DCX+ cells suggesting a potential prosurvival effect of the drug on neuroblasts. More importantly, compared to vehicle, salmeterol promoted ahNG, as demonstrated by an increase in the actual number of BrdU+/NeuN+ cells and in the percentage of BrdU+/NeuN+ cells over the total number of newly generated cells. Interestingly, salmeterol proneurogenic effects were restricted to the ventral hippocampus, an area related to emotional behavior and mood regulation. Since salmeterol is commonly used for asthma therapy in the clinical setting, its novel pharmacological property deserves to be further exploited with a particular focus on drug potential to counteract stress-induced deregulation of ahNG and depressive-like behavior.

Keywords: Neurogenesis, Hippocampus, beta2 adrenergic agonists, Doublecortin (DCX), Neural progenitor, Salmeterol, Norepinephrine

Received: 31 May 2019; Accepted: 06 Aug 2019.

Copyright: © 2019 Bortolotto, Bondi, Cuccurazzu, Rinaldi, Canonico and Grilli. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Mariagrazia Grilli, Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale, Novara, 28100, Italy, mariagrazia.grilli@uniupo.it