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Neuroscience and Behavioral Physiology

, Volume 44, Issue 9, pp 1082–1087 | Cite as

Responses of Rat Brain Interneuronal Synapses to Hypoxia in the Early Neonatal Period

  • V. A. Otellin
  • L. I. Khozhai
  • T. T. Shishko
Article

The responses of forming synapses in the rat neocortex to the actions of hypoxia in the early period of neonatal life (day 2) were studied. Immunocytochemical studies were used to detect synaptophysin and these results, along with electron microscopic studies, addressed the sensorimotor cortex in rat pups at 3, 5, and 10 days of postnatal development (using groups of 6–10 individuals) in an experimental group and a control group (intact animals). Immunocytochemical studies of control animal showed significant differences in the quantitative distribution of synaptophysin-positive structures in different layers of the neocortex during the early neonatal period of development (day 5). Perinatal hypoxia decreased the optical density of the immunocytochemical reaction product more than twofold, and this was accompanied by reductions in the density of synaptophysin-positive granules in all layers of the neocortex. In addition, electron-dense terminals, providing evidence of degenerative processes, were seen. The neuropil of the neocortex showed a sharp decrease in the number of growth cones, small processes, and forming synapses, along with a significant increase in the electron density of synaptic elements, especially postsynaptic membranes and densities. In experimental animals, increases in the numbers of growth cones and forming synaptic structures were seen only by postnatal day 10. Thus, the consequences of hypoxia during the early neonatal period, inducing impairments to synaptogenesis, persisted throughout the study period.

Keywords

neocortex neuron synapse synaptophysin growth cone 

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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • V. A. Otellin
    • 1
  • L. I. Khozhai
    • 1
  • T. T. Shishko
    • 1
  1. 1.Nervous System Ontogeny Laboratory, Institute of PhysiologyRussian Academy of SciencesSt. PetersburgRussia

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