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Development of callosal interhemispheric connection in laboratory rat
Matternová, Lucie ; Mareš, Pavel (advisor) ; Žiak, Jakub (referee)
Corpus callosum is the main commissure linking cortex of the right and left brain hemisphere. For the first time, the callosal axons are observed during E18, when they cross the midline. In PND 5, most axons reach the contralateral cortex, and at the end of the second postnatal week, the callosal projection neurons and axon terminals are located similarly to the adult animal. The interhemispheric response was first observed in the rat in PND 4 but myelination in PND 12, suggesting that the transcallosal response is not dependent on myelinization of callosal fibers. As the rat age increases, the wave duration of the TCR, latency peak and threshold decreases. As opposed to that, amplitude of the positive and negative wave increases with age. TCR may be affected by acute drug application or chronic exposure to various effects, such as hormones.
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The role of CRMP2 in the nervous system development.
Žiak, Jakub ; Balaštík, Martin (advisor) ; Jiruška, Přemysl (referee) ; Horák, Martin (referee)
Regulation of axon guidance and pruning of inappropriate synapses is key to development of neural circuits. Secreted semaphorins are integral part of both processes. Collapsin response mediator protein 2 (CRMP2) has been shown to regulate axon guidance by mediating Semaphorin 3A (Sema3A) signaling, however, nothing is known about its role in the synapse pruning. Similarly, it is also not known if CRMP2 mediates signals from other semaphorins. We herein studied CRMP2 protein and revealed its role in growth and pruning of selected axons and dendrites. In newly generated crmp2-/- and crmp2a-/- mice we demonstrate that CRMP2 has a moderate effect on Sema3A-dependent axon guidance in vivo, and its deficiency leads to a mild defect in axon guidance in peripheral nerves and corpus callosum. CRMP2A isoform is specifically involved in development of callosal axons. Surprisingly, we show that crmp2-/- mice display prominent defects in stereotyped axon pruning in hippocampus and visual cortex and altered dendritic spine remodeling, which are consistent with impaired Sema3F signaling and with models of autism spectrum disorder (ASD). Indeed, we demonstrate that CRMP2 mediates Sema3F signaling in primary neurons and that crmp2-/- mice display ASD-related social behavior changes in early postnatal period as well...
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Development of callosal interhemispheric connection in laboratory rat
Matternová, Lucie ; Mareš, Pavel (advisor) ; Žiak, Jakub (referee)
Corpus callosum is the main commissure linking cortex of the right and left brain hemisphere. For the first time, the callosal axons are observed during E18, when they cross the midline. In PND 5, most axons reach the contralateral cortex, and at the end of the second postnatal week, the callosal projection neurons and axon terminals are located similarly to the adult animal. The interhemispheric response was first observed in the rat in PND 4 but myelination in PND 12, suggesting that the transcallosal response is not dependent on myelinization of callosal fibers. As the rat age increases, the wave duration of the TCR, latency peak and threshold decreases. As opposed to that, amplitude of the positive and negative wave increases with age. TCR may be affected by acute drug application or chronic exposure to various effects, such as hormones.
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