International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience
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Int. J. Dev. Neurosci. · Dec 2015
Neonatal propofol anesthesia modifies activity-dependent processes and induces transient hyperlocomotor response to d-amphetamine during adolescence in rats.
This study examined the influence of propofol anesthesia on the expression of activity-regulated molecules (BDNF and c-Fos) and synaptic plasticity markers (synaptophysin, GAP-43, drebrin) in the frontal cortex and thalamus of 7-day-old (P7) rats. Although these brain regions are the main targets of anesthetic action, they are contained in the cortico-striato-thalamo-cortical feedback loops, involved in naturally occurring and drug-induced psychoses. Therefore, functional integrity of these loops was examined in adolescent and adult rats through d-amphetamine-induced hyperactivity. ⋯ Synaptic plasticity markers changed in a time- and region-specific manner, indicating increased synaptogenesis in the frontal cortex and synapse elimination in the thalamus in P7 rats after the propofol anesthesia exposure. These early molecular changes were followed by time-related, increased motor reaction to d-amphetamine in adolescent, but not in adult rats. Our study revealed that exposure of immature brain to propofol anesthesia during the critical phase of development provoked immediate changes in activity-dependent processes and synaptic adjustment, influencing brain capacity to integrate later developmental events and resulting in temporary altered response to acute psychotropic stimulation during adolescence.
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Int. J. Dev. Neurosci. · Dec 2015
Defects in neural guidepost structures and failure to remove leptomeningeal cells from the septal midline behind the interhemispheric fusion defects in Netrin1 deficient mice.
Corpus callosum (CC) is the largest commissural tract in mammalian brain and it acts to coordinate information between the two cerebral hemispheres. During brain development CC forms at the boundary area between the cortex and the septum and special transient neural and glial guidepost structures in this area are thought to be critical for CC formation. In addition, it is thought that the fusion of the two hemispheres in the septum area is a prerequisite for CC formation. ⋯ At the same time, the Laminin containing basal lamina produced by the leptomeningeal cells is disrupted in the midline area to allow the cells to mix and the callosal axons to cross. In Ntn1 deficient embryos however, the leptomeninges and the basal lamina were not removed properly from the midline area and the septal fusion did not occur. Thus, NTN1 contributes to the formation of the CC by promoting the preceding removal of the midline leptomeningeal cells and interhemispheric fusion.