Abstract
Serotonin (5-HT) has been shown to affect the development and patterning of the mouse barrelfield. We show that the dense transient 5-HT innervation of the somatosensory, visual, and auditory cortices originates in the thalamus rather than in the raphe: 5-HT is detected in thalamocortical fibers and most 5-HT cortical labeling disappears after thalamic lesions. Thalamic neurons do not synthesize 5-HT but take up exogenous 5-HT through 5-HT high affinity uptake sites located on thalamocortical axons and terminals. 3H-5-HT injected into the cortex is retrogradely transported to thalamic neurons. In situ hybridization shows a transient expression of the genes encoding the serotonin transporter and the vesicular monoamine transporter in thalamic sensory neurons. In these glutamatergic neurons, internalized 5-HT might thus be stored and used as a "borrowed transmitter" for extraneuronal signaling or could exert an intraneuronal control on thalamic maturation.
MeSH terms
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Age Factors
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Animals
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Antibody Specificity
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Biological Transport / physiology
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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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Cerebral Cortex / cytology
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Cerebral Cortex / metabolism
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Gene Expression / physiology
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Immunohistochemistry
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In Situ Hybridization
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Membrane Glycoproteins / analysis
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism
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Membrane Transport Proteins*
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Mice
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Mice, Inbred C57BL
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Nerve Tissue Proteins*
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Neurons, Afferent / chemistry
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Neurons, Afferent / metabolism*
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Neuropeptides*
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Neurotransmitter Agents / analysis
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Neurotransmitter Agents / genetics
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Neurotransmitter Agents / metabolism
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RNA, Messenger / analysis
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Rats
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Rats, Sprague-Dawley
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Serotonin / biosynthesis
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Serotonin / immunology
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Serotonin / pharmacokinetics*
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Serotonin Plasma Membrane Transport Proteins
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Synaptic Vesicles / metabolism
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Thalamus / cytology*
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Thalamus / growth & development
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Thalamus / metabolism
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Time Factors
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Tritium
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Vesicular Biogenic Amine Transport Proteins
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Vesicular Monoamine Transport Proteins
Substances
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Carrier Proteins
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Membrane Glycoproteins
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Membrane Transport Proteins
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Nerve Tissue Proteins
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Neuropeptides
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Neurotransmitter Agents
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RNA, Messenger
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Serotonin Plasma Membrane Transport Proteins
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Slc6a4 protein, mouse
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Slc6a4 protein, rat
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Vesicular Biogenic Amine Transport Proteins
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Vesicular Monoamine Transport Proteins
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Tritium
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Serotonin