RT Journal Article SR Electronic T1 Perturbation of Serotonin Homeostasis during Adulthood Affects Serotonergic Neuronal Circuitry JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0376-16.2017 DO 10.1523/ENEURO.0376-16.2017 VO 4 IS 2 A1 Marta Pratelli A1 Sara Migliarini A1 Barbara Pelosi A1 Francesco Napolitano A1 Alessandro Usiello A1 Massimo Pasqualetti YR 2017 UL http://www.eneuro.org/content/4/2/ENEURO.0376-16.2017.abstract AB Growing evidence shows that the neurotransmitter serotonin (5-HT) modulates the fine-tuning of neuron development and the establishment of wiring patterns in the brain. However, whether serotonin is involved in the maintenance of neuronal circuitry in the adult brain remains elusive. Here, we use a Tph2fl°x conditional knockout (cKO) mouse line to assess the impact of serotonin depletion during adulthood on serotonergic system organization. Data show that the density of serotonergic fibers is increased in the hippocampus and decreased in the thalamic paraventricular nucleus (PVN) as a consequence of brain serotonin depletion. Strikingly, these defects are rescued following reestablishment of brain 5-HT signaling via administration of the serotonin precursor 5-hydroxytryptophan (5-HTP). Finally, 3D reconstruction of serotonergic fibers reveals that changes in serotonin homeostasis affect axonal branching complexity. These data demonstrate that maintaining proper serotonin homeostasis in the adult brain is crucial to preserve the correct serotonergic axonal wiring.