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  - 
TY  - JOUR
A1  - Waider, Jonas
A1  - Popp, Sandy
A1  - Mlinar, Boris
A1  - Montalbano, Alberto
A1  - Bonfiglio, Francesco
A1  - Aboagye, Benjamin
A1  - Thuy, Elisabeth
A1  - Kern, Raphael
A1  - Thiel, Christopher
A1  - Araragi, Naozumi
A1  - Svirin, Evgeniy
A1  - Schmitt-Böhrer, Angelika G.
A1  - Corradetti, Renato
A1  - Lowry, Christopher A.
A1  - Lesch, Klaus-Peter
T1  - Serotonin deficiency increases context-dependent fear learning through modulation of hippocampal activity
JF  - Frontiers in Neuroscience
N2  - Brain serotonin (5-hydroxytryptamine, 5-HT) system dysfunction is implicated in exaggerated fear responses triggering various anxiety-, stress-, and trauma-related disorders. However, the underlying mechanisms are not well understood. Here, we investigated the impact of constitutively inactivated 5-HT synthesis on context-dependent fear learning and extinction using tryptophan hydroxylase 2 (Tph2) knockout mice. Fear conditioning and context-dependent fear memory extinction paradigms were combined with c-Fos imaging and electrophysiological recordings in the dorsal hippocampus (dHip). Tph2 mutant mice, completely devoid of 5-HT synthesis in brain, displayed accelerated fear memory formation and increased locomotor responses to foot shock. Furthermore, recall of context-dependent fear memory was increased. The behavioral responses were associated with increased c-Fos expression in the dHip and resistance to foot shock-induced impairment of hippocampal long-term potentiation (LTP). In conclusion, increased context-dependent fear memory resulting from brain 5-HT deficiency involves dysfunction of the hippocampal circuitry controlling contextual representation of fear-related behavioral responses.
KW  - tryptophan hydroxylase 2
KW  - knockout
KW  - fear learning
KW  - extinction
KW  - long-term potentiation
KW  - hippocampus
KW  - immediate-early gene
KW  - serotonin deficiency
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196077
SN  - 1662-453X
VL  - 13
IS  - 245
ER  -