Barrel pattern formation requires serotonin uptake by thalamocortical afferents, and not vesicular monoamine release.
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.
Persico
A M
AM
Laboratory of Neuroscience, Università "Campus Bio-Medico," 00155 Rome, Italy.
Mengual
E
E
Moessner
R
R
Hall
F S
FS
Revay
R S
RS
Sora
I
I
Arellano
J
J
DeFelipe
J
J
Gimenez-Amaya
J M
JM
Conciatori
M
M
Marino
R
R
Baldi
A
A
Cabib
S
S
Pascucci
T
T
Uhl
G R
GR
Murphy
D L
DL
Lesch
K P
KP
Keller
F
F
Hall
S F
SF
D000375:Aging / Q000378:metabolism; D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D010134:Fenclonine / Q000494:pharmacology; D050485:GABA Plasma Membrane Transport Proteins; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D026901:Membrane Transport Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins; D009475:Neurons, Afferent / Q000378:metabolism* / Q000648:ultrastructure; D009479:Neuropeptides; D027361:Organic Anion Transporters; D012701:Serotonin / Q000032:analysis / Q000378:metabolism; D012702:Serotonin Antagonists / Q000494:pharmacology; D050486:Serotonin Plasma Membrane Transport Proteins; D013003:Somatosensory Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000378:metabolism*; D013788:Thalamus / Q000166:cytology / Q000378:metabolism*; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins; D014738:Vibrissae / Q000294:innervation / Q000502:physiology
D015306:Biogenic Monoamines; D002352:Carrier Proteins; D050485:GABA Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D027361:Organic Anion Transporters; D012702:Serotonin Antagonists; D050486:Serotonin Plasma Membrane Transport Proteins; C493453:Slc18a2 protein, mouse; C493231:Slc6a4 protein, mouse; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins; D012701:Serotonin; D010134:Fenclonine