Development of posterior hypothalamic neurons enlightens a switch in the prosencephalic basic plan

• Published in: PloS one Vol. 6; no. 12; p. e28574
• Main Authors: Croizier, Sophie, Amiot, Clotilde, Chen, Xiaoping, Presse, Françoise, Nahon, Jean-Louis, Wu, Jane Y, Fellmann, Dominique, Risold, Pierre-Yves
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.12.2011; Public Library of Science (PLoS)
• Subjects: Adenoviruses; Amphetamines; Animals; Axons; Axons - metabolism; Biology; Brain; Bromodeoxyuridine; Bromodeoxyuridine - metabolism; Cell Differentiation; Cerebral cortex; Cocaine; Diencephalon; Dopamine receptors; Embryo, Mammalian; Embryo, Mammalian - metabolism; Embryos; Forebrain; Gene expression; Gene Expression Regulation, Developmental; Genes; Green Fluorescent Proteins; Green Fluorescent Proteins - metabolism; Hedgehog protein; Hedgehog Proteins; Hedgehog Proteins - metabolism; Hybridization; Hypothalamic Hormones; Hypothalamic Hormones - metabolism; Hypothalamus; Hypothalamus - cytology; Hypothalamus - metabolism; Intercellular Signaling Peptides and Proteins; Intercellular Signaling Peptides and Proteins - metabolism; Life Sciences; Medial forebrain bundle; Melanin; Melanin-concentrating hormone; Melanins; Melanins - metabolism; Mesencephalon; Mesencephalon - cytology; Mesencephalon - metabolism; Mice; Models, Biological; Nerve Growth Factors; Nerve Growth Factors - metabolism; Nerve Tissue Proteins; Nerve Tissue Proteins - metabolism; Netrin-1; Neural tube; Neuroblasts; Neurogenesis; Neurons; Neurons - cytology; Neurons - metabolism; Neurons and Cognition; Neuropeptides; Nkx2.2 protein; Phenotype; Pituitary Hormones; Pituitary Hormones - metabolism; Proteins; Rats; Receptors, Immunologic; Receptors, Immunologic - metabolism; Rodents; Spinal cord; Stem cells; Telencephalon; Telencephalon - cytology; Telencephalon - metabolism; Time Factors; Transcription; Tumor Suppressor Proteins; Tumor Suppressor Proteins - metabolism; Chicago Illinois; France; United States > US; Illinois
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0028574

In rats and mice, ascending and descending axons from neurons producing melanin-concentrating hormone (MCH) reach the cerebral cortex and spinal cord. However, these ascending and descending projections originate from distinct sub-populations expressing or not "Cocaine-and-Amphetamine-Regulated-Transcript" (CART) peptide. Using a BrdU approach, MCH cell bodies are among the very first generated in the hypothalamus, within a longitudinal cell cord made of earliest delaminating neuroblasts in the diencephalon and extending from the chiasmatic region to the ventral midbrain. This region also specifically expresses the regulatory genes Sonic hedgehog (Shh) and Nkx2.2. First MCH axons run through the tractus postopticus (tpoc) which gathers pioneer axons from the cell cord and courses parallel to the Shh/Nkx2.2 expression domain. Subsequently generated MCH neurons and ascending MCH axons differentiate while neurogenesis and mantle layer differentiation are generalized in the prosencephalon, including telencephalon. Ascending MCH axons follow dopaminergic axons of the mesotelencephalic tract, both being an initial component of the medial forebrain bundle (mfb). Netrin1 and Slit2 proteins that are involved in the establishment of the tpoc and mfb, respectively attract or repulse MCH axons.We conclude that first generated MCH neurons develop in a diencephalic segment of a longitudinal Shh/Nkx2.2 domain. This region can be seen as a prosencephalic segment of a medial neurogenic column extending from the chiasmatic region through the ventral neural tube. However, as the telencephalon expends, it exerts a trophic action and the mfb expands, inducing a switch in the longitudinal axial organization of the prosencephalon.