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.
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References
S. V. Lebedev, A. V. Karasev, S. O. Rogatkin, et al., “Problems and perspectives in the experimental modeling of hypoxic-ischemic damage to the central nervous system,” Vestn. Ros. Adak. Med. Nauk., No. 2, 21–26 (2009).
I. B. Ushakov and V. P. Fedorov, Oxygen. Radiation. The Brain., Nauch. Kniga, Voronezh (2011).
E. Cebral and C. F. Loidl, “Changes in neostriatal and hippocampal synaptic densities in perinatal asphyctic male and female young rat: role of hypothermia,” Brain Res. Bull., 84, No. 1, 31–38 (2011).
B. Clancy, R. B. Darlington, and B. L. Finlay, “Translating developmental time across mammalian species,” Neuroscience, 106, No. 1, 7–17 (2001).
J. M. Dean, M. D. Moravec, M. Grafe, et al., “Strain-specific differences in perinatal rodent oligodendrocyte lineage progression and its correlation with human,” Dev. Neurosci., 33, No. 3–4, 251–260 (2011).
J. J. Garcia-Penas, J. Dominguez-Carral, and E. Pereira-Bezanilla, “Abnormalities of synaptogenesis in autism. Pathogenic and therapeutic implications,” Rev. Neurol., 54, Suppl. 1, 1–50 (2012).
L. K. Laeme, K. B. Repke, R. Hawkes, and F. L. Rice, “Synaptogenesis in the rat suprachiasmatic nucleus: a light microscopic immunocytochemical survey,” Brain Res., 544, No. 1, 108–117 (1991).
M. Li, Z. Cui, Y. Niu, et al., “Synaptogenesis in the developing mouse visual cortex,” Brain Res. Bull., 81, No. 1, 107–113 (2010).
H. J. Pyeon and Y. I. Lee, “Differential expression levels of synaptophysin through developmental stages in hippocampal region of mouse brain,” Anat. Cell Biol., 45, No. 2, 97–102 (2012).
G. E. Saraceno, M. V. Avala, M. S. Badorrey, et al., “Effects of perinatal asphyxia on rat striatal cytoskeleton,” Synapse, 66, No. 1, 9–19 (2012).
H. B. Sarnat, R. N. Auer, and L. Flores-Sarnat, “Synaptogenesis in the fetal corpus striatum, globus pallidus, and substantia nigra: correlation with striosomes of Graybiel and dyskinesias in premature infants,” J. Child Neurol., 28, No. 1, 60–69 (2013).
H. B. Sarnat and D. E. Born, “Synaptophysin immunocytochemistry with thermal intensification: a marker of terminal axonal maturation in the human fetal nervous system” Brain Dev., 21, No. 1, 41–50 (1999).
H. B. Sarnat, L. Flores-Sarnat, and C. L. Trevenen, “Synaptophysin immunoreactivity in the human hippocampus and neocortex from 6 to 41 weeks of gestation,” J. Neuropathol. Exp. Neurol., 69, No. 3, 234–245 (2010).
E. Strackx, D. L. Van den Hove, H. P. Steinbusch, et al., “Fetal asphyxia leads to the loss of striatal boutons in adult rats,” Int. J. Dev. Neurosci., 28, No. 3, 277–281 (2010).
S. J. Vannucci and H. Hagberg, “Hypoxia-ischemia in the immature brain,” J. Exp. Biol., 207, No. 18, 3149–3154 (2004).
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Translated from Morfologiya, Vol. 145, No. 1, pp. 7–12, January–February, 2014.
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Otellin, V.A., Khozhai, L.I. & Shishko, T.T. Responses of Rat Brain Interneuronal Synapses to Hypoxia in the Early Neonatal Period. Neurosci Behav Physi 44, 1082–1087 (2014). https://doi.org/10.1007/s11055-014-0029-9
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DOI: https://doi.org/10.1007/s11055-014-0029-9