Location and size of dopaminergic and serotonergic cell populations are controlled by the position of the midbrain-hindbrain organizer.
Midbrain dopaminergic and hindbrain serotonergic neurons play an important role in the modulation of behavior and are involved in a series of neuropsychiatric disorders. Despite the importance of these cells, little is known about the molecular mechanisms governing their development. During embryogenesis, midbrain dopaminergic neurons are specified rostral to the midbrain-hindbrain organizer (MHO), and hindbrain serotonergic neurons are specified caudal to it. We report that in transgenic mice in which Otx2 and accordingly the MHO are shifted caudally, the midbrain dopaminergic neuronal population expands to the ectopically positioned MHO and is enlarged. Complementary, the extension of the hindbrain serotonergic cell group is decreased. These changes are preserved in adulthood, and the additional, ectopic dopaminergic neurons project to the striatum, which is a proper dopaminergic target area. In addition, in mutants in which Otx2 and the MHO are shifted rostrally, dopaminergic and serotonergic neurons are relocated at the newly positioned MHO. However, in these mice, the size ratio between these two cell populations is changed in favor of the serotonergic cell population. To investigate whether the position of the MHO during embryogenesis is also of functional relevance for adult behavior, we tested mice with a caudally shifted MHO and report that these mutants show a higher locomotor activity. Together, we provide evidence that the position of the MHO determines the location and size of midbrain dopaminergic and hindbrain serotonergic cell populations in vivo. In addition, our data suggest that the position of the MHO during embryogenesis can modulate adult locomotor activity.
Brodski
Claude
C
Max-Planck-Institute of Psychiatry, 80804 Munich, Germany, and GSF-National Research Center for Environment and Health, Technical University Munich, Institute of Developmental Genetics, 85758 Oberschleissheim, Germany.
Weisenhorn
Daniela M Vogt
DM
Signore
Massimo
M
Sillaber
Inge
I
Oesterheld
Matthias
M
Broccoli
Vania
V
Acampora
Dario
D
Simeone
Antonio
A
Wurst
Wolfgang
W
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001931:Brain Mapping / Q000379:methods; D004298:Dopamine / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D008297:Male; D008636:Mesencephalon / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D020897:Organizers, Embryonic / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D051857:Otx Transcription Factors; D012249:Rhombencephalon / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D012701:Serotonin / Q000502:physiology; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics / Q000502:physiology
D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D051857:Otx Transcription Factors; C497660:Otx2 protein, mouse; D015534:Trans-Activators; D012701:Serotonin; D004298:Dopamine