Morphological organization of somatosensory cortex in Otxl(-/-) mice

TY - JOUR

T1 - Morphological organization of somatosensory cortex in Otxl(-/-) mice

AU - Cipelletti, B

AU - Avanzini, G

AU - Vitellaro-Zuccarello, L

AU - Franceschetti, S

AU - Sancini, G

AU - Lavazza, T

AU - Acampora, D

AU - Simeone, A

AU - Spreafico, R

AU - Frassoni, C

PY - 2002/12/9

Y1 - 2002/12/9

N2 - Knock-out Otx1 mice show brain hypoplasia, spontaneous epileptic seizures and abnormalities of the dorsal region of the neocortex. We investigated structural alterations in excitatory and inhibitory circuits in somatosensory cortex of Otx1(-/-) mice by immunocytochemistry using light, confocal and electron microscopy. Immunostaining for non-phosphorylated neurofilament SM1311 and subunit I of the NMDA receptor - used as markers of pyramidal neurons - showed reduced layer V pyramidal cells and ectopic pyramidal cells in layers II and III of the mutant cortex. Immunostaining for calcium-binding proteins calbindin, calretinin and parvalbumin - markers of non-overlapping types of GABAergic interneurons - showed no differences between wild-type and knock-out cortex for calbindin and calretinin neurons, while parvalbumin neurons were only patchily distributed in Otx1(-/-) cortex. The pattern of positivity of the GABAergic marker glutamic acid decarboxylase in Otx1(-/-) cortex was also altered and similar to that of parvalbumin. GABA transporter I immunoreactivity was greater in Otx1(-/-) than wild-type; quantitation of structures immunoreactive for this transporter in layer V showed that they were increased overall in Otx1(-/-) but the density of inhibitory terminals on pyramidal neurons in the same layer labeled with this transporter was similar to that in wild-type mice. No differences in the distribution or intensity of the glial markers GABA transporter 3 or glial fibrillary acidic protein were found. The defects found in the cortical GABAergic system of the Otx1(-/-) mouse can plausibly explain the cortical hyperexcitability that produces seizures in these animals. (C) 2002 IBRO. Published by Elsevier Science Ltd. All rights reserved.

AB - Knock-out Otx1 mice show brain hypoplasia, spontaneous epileptic seizures and abnormalities of the dorsal region of the neocortex. We investigated structural alterations in excitatory and inhibitory circuits in somatosensory cortex of Otx1(-/-) mice by immunocytochemistry using light, confocal and electron microscopy. Immunostaining for non-phosphorylated neurofilament SM1311 and subunit I of the NMDA receptor - used as markers of pyramidal neurons - showed reduced layer V pyramidal cells and ectopic pyramidal cells in layers II and III of the mutant cortex. Immunostaining for calcium-binding proteins calbindin, calretinin and parvalbumin - markers of non-overlapping types of GABAergic interneurons - showed no differences between wild-type and knock-out cortex for calbindin and calretinin neurons, while parvalbumin neurons were only patchily distributed in Otx1(-/-) cortex. The pattern of positivity of the GABAergic marker glutamic acid decarboxylase in Otx1(-/-) cortex was also altered and similar to that of parvalbumin. GABA transporter I immunoreactivity was greater in Otx1(-/-) than wild-type; quantitation of structures immunoreactive for this transporter in layer V showed that they were increased overall in Otx1(-/-) but the density of inhibitory terminals on pyramidal neurons in the same layer labeled with this transporter was similar to that in wild-type mice. No differences in the distribution or intensity of the glial markers GABA transporter 3 or glial fibrillary acidic protein were found. The defects found in the cortical GABAergic system of the Otx1(-/-) mouse can plausibly explain the cortical hyperexcitability that produces seizures in these animals. (C) 2002 IBRO. Published by Elsevier Science Ltd. All rights reserved.

UR - http://www.scopus.com/inward/record.url?scp=0037049258&partnerID=8YFLogxK

U2 - 10.1016/S0306-4522(02)00531-6

DO - 10.1016/S0306-4522(02)00531-6

M3 - Article

VL - 115

SP - 657

EP - 667

JO - Neuroscience

JF - Neuroscience

IS - 3

ER -