Cytochemical Redistribution of 5'-Nucleotidase in the Developing Cat Visual Cortex |
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Authors: | S. W. Schoen G. W. Kreutzberg W. Singer |
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Affiliation: | Department of Neurophysiology, Max Planck Institute for Brain Research, Deutschordenstraße 46, W-6000 Frankfurt 71, FRG. Department of Neuromorphology, Max Planck Institute for Psychiatry, W-8033 Martinsried, FRG;Department of Neuromorphology, Max Planck Institute for Psychiatry, W-8033 Martinsried, FRG;Department of Neurophysiology, Max Planck Institute for Brain Research, Deutschordenstraße 46, W-6000 Frankfurt 71, FRG. |
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Abstract: | The adenosine-producing ectoenzyme 5'-nucleotidase has recently been shown to undergo a marked redistribution during development of the cat visual cortex and to be involved in the remodelling of ocular dominance columns (Schoen et al., J. Comp. Neurol. , 296 , 379 – 392, 1990). Using an enzyme-cytochemical technique, we now investigate the developmental redistribution of 5'-nucleotidase activity in area 17 of kittens at the ultrastructural level. Between postnatal days 35 and 42, when 5'-nucleotidase is concentrated in layer IV, enzyme reaction product occupies the clefts of asymmetrical synapses within the neuropil. During later development (9th and 13th postnatal weeks), when 5'-nucleotidase spreads over all cortical laminae, the enzyme disappears from its synaptic localization and becomes increasingly associated with astrocytic membranes. The transient appearance of 5'-nucleotidase at synapses parallels the time-course and laminar profile of the synaptic remodelling which takes place during the critical period of visual cortex development. This suggests that synapse-bound 5'-nucleotidase activity plays a role in synaptic malleability, whereas its later association with glial profiles is likely to reflect other functions of the enzyme. |
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Keywords: | critical period synaptic plasticity astrocytes adenosine cell adhesion |
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