Neonatal depletion of serotonin increases the numbers of callosally projecting neurons in cat visual areas 17 and 18.
We investigated the influence of neonatal depletion of serotonin on the developmental reduction of callosal connections in cat visual cortex. Neonatal kittens were injected with 5,7-dihydroxytryptamine. At the age of 3 months, Fast Blue was injected into visual areas of one hemisphere in these and control cats and retrogradely labeled perikarya were mapped in the opposite hemisphere. In both groups callosally projecting neurons were found in a 3-5 mm wide belt centered on the transient zone of areas 17 and 18. However, numbers of labeled neurons were twice higher in the serotonin-depleted cats. We postulate that normally serotonin intensifies the process of axon pruning by augmenting developmental plasticity, therefore its depletion reduced the plasticity and more axons targeting callosal zones were stabilized, even though ectopic projections were still eliminated.
Department of Neurophysiology, Nencki Institute of Experimental Biology, 3 Pasteur St, 02-093, Warsaw, Poland. r.djavadian@nencki.gov.pl
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Djavadian
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Wielkopolska
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Turlejski
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002415:Cats; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D003337:Corpus Callosum / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000172:deficiency* / Q000378:metabolism; D018490:Serotonin Agents / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D014793:Visual Cortex / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*
D005456:Fluorescent Dyes; D018490:Serotonin Agents; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin