TY - JOUR A1 - Gutknecht, Lise A1 - Araragi, Naozumi A1 - Merker, Sören A1 - Waider, Jonas A1 - Sommerlandt, Frank M. J. A1 - Mlinar, Boris A1 - Baccini, Gilda A1 - Mayer, Ute A1 - Proft, Florian A1 - Hamon, Michel A1 - Schmitt, Angelika G. A1 - Corradetti, Renato A1 - Lanfumey, Laurence A1 - Lesch, Klaus-Peter T1 - Impacts of Brain Serotonin Deficiency following Tph2 Inactivation on Development and Raphe Neuron Serotonergic Specification JF - PLoS One N2 - Brain serotonin (5-HT) is implicated in a wide range of functions from basic physiological mechanisms to complex behaviors, including neuropsychiatric conditions, as well as in developmental processes. Increasing evidence links 5-HT signaling alterations during development to emotional dysregulation and psychopathology in adult age. To further analyze the importance of brain 5-HT in somatic and brain development and function, and more specifically differentiation and specification of the serotonergic system itself, we generated a mouse model with brain-specific 5-HT deficiency resulting from a genetically driven constitutive inactivation of neuronal tryptophan hydroxylase-2 (Tph2). Tph2 inactivation (Tph2-/-) resulted in brain 5-HT deficiency leading to growth retardation and persistent leanness, whereas a sex- and age-dependent increase in body weight was observed in Tph2+/- mice. The conserved expression pattern of the 5-HT neuron-specific markers (except Tph2 and 5-HT) demonstrates that brain 5-HT synthesis is not a prerequisite for the proliferation, differentiation and survival of raphe neurons subjected to the developmental program of serotonergic specification. Furthermore, although these neurons are unable to synthesize 5-HT from the precursor tryptophan, they still display electrophysiological properties characteristic of 5-HT neurons. Moreover, 5-HT deficiency induces an up-regulation of 5-HT\(_{1A}\) and 5-HT\(_{1B}\) receptors across brain regions as well as a reduction of norepinephrine concentrations accompanied by a reduced number of noradrenergic neurons. Together, our results characterize developmental, neurochemical, neurobiological and electrophysiological consequences of brain-specific 5-HT deficiency, reveal a dual dose-dependent role of 5-HT in body weight regulation and show that differentiation of serotonergic neuron phenotype is independent from endogenous 5-HT synthesis. KW - lacking KW - knock-out mice KW - energy expenditure KW - locomotor activity KW - 5-HT transporter KW - anxiety like KW - receptors KW - behavior KW - tryptophan KW - nucleus Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133728 VL - 7 IS - 8 ER -