Abstract
Thalamocortical neurons innervating the barrel cortex in neonatal rodents transiently store serotonin (5-HT) in synaptic vesicles by expressing the plasma membrane serotonin transporter (5-HTT) and the vesicular monoamine transporter (VMAT2). 5-HTT knock-out (ko) mice reveal a nearly complete absence of 5-HT in the cerebral cortex by immunohistochemistry, and of barrels, both at P7 and adulthood. Quantitative electron microscopy reveals that 5-HTT ko affects neither the density of synapses nor the length of synaptic contacts in layer IV. VMAT2 ko mice, completely lacking activity-dependent vesicular release of monoamines including 5-HT, also show a complete lack of 5-HT in the cortex but display largely normal barrel fields, despite sometimes markedly reduced postnatal growth. Transient 5-HTT expression is thus required for barrel pattern formation, whereas activity-dependent vesicular 5-HT release is not.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Aging / metabolism
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Animals
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Biogenic Monoamines / metabolism*
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Carrier Proteins / analysis
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Extracellular Space / metabolism
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Fenclonine / pharmacology
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GABA Plasma Membrane Transport Proteins
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Immunohistochemistry
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Membrane Glycoproteins / deficiency
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Membrane Glycoproteins / genetics
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Membrane Proteins / analysis
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Membrane Proteins / metabolism
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Membrane Transport Proteins*
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Nerve Tissue Proteins*
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Neurons, Afferent / metabolism*
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Neurons, Afferent / ultrastructure
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Neuropeptides*
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Organic Anion Transporters*
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Serotonin / analysis
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Serotonin / metabolism
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Serotonin Antagonists / pharmacology
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Serotonin Plasma Membrane Transport Proteins
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Somatosensory Cortex / cytology
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Somatosensory Cortex / drug effects
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Somatosensory Cortex / metabolism*
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Synapses / metabolism
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Synapses / ultrastructure
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Synaptic Vesicles / metabolism*
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Thalamus / cytology
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Thalamus / metabolism*
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Vesicular Biogenic Amine Transport Proteins
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Vesicular Monoamine Transport Proteins
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Vibrissae / innervation
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Vibrissae / physiology
Substances
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Biogenic Monoamines
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Carrier Proteins
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GABA Plasma Membrane Transport Proteins
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Membrane Glycoproteins
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Membrane Proteins
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Membrane Transport Proteins
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Nerve Tissue Proteins
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Neuropeptides
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Organic Anion Transporters
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Serotonin Antagonists
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Serotonin Plasma Membrane Transport Proteins
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Slc18a2 protein, mouse
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Slc6a4 protein, mouse
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Vesicular Biogenic Amine Transport Proteins
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Vesicular Monoamine Transport Proteins
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Serotonin
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Fenclonine