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Prenatal Hypoxia in Different Periods of Embryogenesis Differentially Affects Cell Migration, Neuronal Plasticity, and Rat Behavior in Postnatal Ontogenesis.

Vasilev DS, Dubrovskaya NM, Tumanova NL, Zhuravin IA - Front Neurosci (2016)

Bottom Line: In control rat pups a majority of cells labeled on E14 were localized in the lower cortical layers V-VI while the cells labeled on E18 were mainly found in the superficial cortical layers II-III.In rat pups subjected to hypoxia on E18, the total number of labeled cells in the parietal cortex was also decreased but the number of scattered labeled neurons was higher in the lower cortical layers.Hypoxia on E18 does not significantly affect cortical structure and parietal cortex-dependent behavioral tasks.

View Article: PubMed Central - PubMed

Affiliation: I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of SciencesSaint Petersburg, Russia; Research Center, Saint-Petersburg State Pediatric Medical UniversitySaint Petersburg, Russia.

ABSTRACT
Long-term effects of prenatal hypoxia on embryonic days E14 or E18 on the number, type and localization of cortical neurons, density of labile synaptopodin-positive dendritic spines, and parietal cortex-dependent behavioral tasks were examined in the postnatal ontogenesis of rats. An injection of 5'ethynyl-2'deoxyuridine to pregnant rats was used to label neurons generated on E14 or E18 in the fetuses. In control rat pups a majority of cells labeled on E14 were localized in the lower cortical layers V-VI while the cells labeled on E18 were mainly found in the superficial cortical layers II-III. It was shown that hypoxia both on E14 and E18 results in disruption of neuroblast generation and migration but affects different cell populations. In rat pups subjected to hypoxia on E14, the total number of labeled cells in the parietal cortex was decreased while the number of labeled neurons scattered within the superficial cortical layers was increased. In rat pups subjected to hypoxia on E18, the total number of labeled cells in the parietal cortex was also decreased but the number of scattered labeled neurons was higher in the lower cortical layers. It can be suggested that prenatal hypoxia both on E14 and E18 causes a disruption in neuroblast migration but with a different outcome. Only in rats subjected to hypoxia on E14 did we observe a reduction in the total number of pyramidal cortical neurons and the density of labile synaptopodin-positive dendritic spines in the molecular cortical layer during the first month after birth which affected development of the cortical functions. As a result, rats subjected to hypoxia on E14, but not on E18, had impaired development of the whisker-placing reaction and reduced ability to learn reaching by a forepaw. The data obtained suggest that hypoxia on E14 in the period of generation of the cells, which later differentiate into the pyramidal cortical neurons of the V-VI layers and form cortical minicolumns, affects formation of cortical cytoarchitecture, neuronal plasticity and behavior in postnatal ontogenesis which testify to cortical dysfunction. Hypoxia on E18 does not significantly affect cortical structure and parietal cortex-dependent behavioral tasks.

No MeSH data available.


Related in: MedlinePlus

Expression and distribution of synapse-associated proteins in rat cortical tissue on P90. (A) Distribution of an actin-associated protein synaptopodin in the molecular layer of the parietal cortex, adult control rat. Scale: 10 μm. Indirect immunofluorescence, excitation—488 nm wavelength, emission—552–690 nm wavelength. (B) Number of labile synaptopodin-labeled dendritic spines in the molecular layer of the parietal cortex in adult rats (P90). Ordinate: number of synaptopodin-positive spines per 100 × 100 μm area. *Statistically significant changes compared to the control (p ≤ 0.001). (C) Immunoblotting of proteins from adult rat cortical tissue with antibodies against synaptopodin (100 kDa), PSD95 (95 kDa), synaptophysin (37 kDa), and actin (45 kDa). (D) Ratio of the intensity of the bands corresponding to the proteins of interest (white columns—spine-associated protein synaptopodin, gray columns—postsynaptic marker protein PSD95, dotted columns—presynaptic marker synaptophysin) to the intensity of the band of actin. Data presented as the mean ratio of optical density ± SEM. *Statistically significant decrease in synaptopodin expression in adult rats subjected to hypoxia on E14 compared to controls, p ≤ 0.05. No significant changes in PSD95 and synaptophysin can be seen n = 8 in each group of animals. (E) Electrophoretic separation of young (P30) rat cortical tissue proteins and subsequent immunoblotting against synaptopodin (100 kDa), PSD95 (95 kDa), and actin (45 kDa). (F) Ratio of the band intensity of the protein of interest (white, dotted columns—spine-associated protein synaptopodin, gray columns—the postsynaptic marker protein PSD95) to the actin band intensity in young (P30) rat cortical tissue. Data presented as mean optical density ratio ± SEM. Asterisk—significant difference in synaptopodin or PSD95 protein expression between control rats and rats exposed to hypoxia on E14 (two-tailed Mann–Whitney U-test with independent samples, p ≤ 0.05). No significant changes were shown in rats exposed to hypoxia on E18. N = 4 in each group of animals.
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Figure 3: Expression and distribution of synapse-associated proteins in rat cortical tissue on P90. (A) Distribution of an actin-associated protein synaptopodin in the molecular layer of the parietal cortex, adult control rat. Scale: 10 μm. Indirect immunofluorescence, excitation—488 nm wavelength, emission—552–690 nm wavelength. (B) Number of labile synaptopodin-labeled dendritic spines in the molecular layer of the parietal cortex in adult rats (P90). Ordinate: number of synaptopodin-positive spines per 100 × 100 μm area. *Statistically significant changes compared to the control (p ≤ 0.001). (C) Immunoblotting of proteins from adult rat cortical tissue with antibodies against synaptopodin (100 kDa), PSD95 (95 kDa), synaptophysin (37 kDa), and actin (45 kDa). (D) Ratio of the intensity of the bands corresponding to the proteins of interest (white columns—spine-associated protein synaptopodin, gray columns—postsynaptic marker protein PSD95, dotted columns—presynaptic marker synaptophysin) to the intensity of the band of actin. Data presented as the mean ratio of optical density ± SEM. *Statistically significant decrease in synaptopodin expression in adult rats subjected to hypoxia on E14 compared to controls, p ≤ 0.05. No significant changes in PSD95 and synaptophysin can be seen n = 8 in each group of animals. (E) Electrophoretic separation of young (P30) rat cortical tissue proteins and subsequent immunoblotting against synaptopodin (100 kDa), PSD95 (95 kDa), and actin (45 kDa). (F) Ratio of the band intensity of the protein of interest (white, dotted columns—spine-associated protein synaptopodin, gray columns—the postsynaptic marker protein PSD95) to the actin band intensity in young (P30) rat cortical tissue. Data presented as mean optical density ratio ± SEM. Asterisk—significant difference in synaptopodin or PSD95 protein expression between control rats and rats exposed to hypoxia on E14 (two-tailed Mann–Whitney U-test with independent samples, p ≤ 0.05). No significant changes were shown in rats exposed to hypoxia on E18. N = 4 in each group of animals.

Mentions: The pattern of distribution of the actin-associated protein synaptopodin in control adult rats on P90 is given in Figure 3A demonstrating that the majority of this protein is located in dendritic spines (immunopositive dots, 1 μm in diameter) in the molecular layer of brain cortex. On the other hand, the immunolabeled postsynaptic protein PSD95 was mostly placed near the synaptophysin-positive presynaptic terminals in different (but mostly in the molecular) cortical layers.


Prenatal Hypoxia in Different Periods of Embryogenesis Differentially Affects Cell Migration, Neuronal Plasticity, and Rat Behavior in Postnatal Ontogenesis.

Vasilev DS, Dubrovskaya NM, Tumanova NL, Zhuravin IA - Front Neurosci (2016)

Expression and distribution of synapse-associated proteins in rat cortical tissue on P90. (A) Distribution of an actin-associated protein synaptopodin in the molecular layer of the parietal cortex, adult control rat. Scale: 10 μm. Indirect immunofluorescence, excitation—488 nm wavelength, emission—552–690 nm wavelength. (B) Number of labile synaptopodin-labeled dendritic spines in the molecular layer of the parietal cortex in adult rats (P90). Ordinate: number of synaptopodin-positive spines per 100 × 100 μm area. *Statistically significant changes compared to the control (p ≤ 0.001). (C) Immunoblotting of proteins from adult rat cortical tissue with antibodies against synaptopodin (100 kDa), PSD95 (95 kDa), synaptophysin (37 kDa), and actin (45 kDa). (D) Ratio of the intensity of the bands corresponding to the proteins of interest (white columns—spine-associated protein synaptopodin, gray columns—postsynaptic marker protein PSD95, dotted columns—presynaptic marker synaptophysin) to the intensity of the band of actin. Data presented as the mean ratio of optical density ± SEM. *Statistically significant decrease in synaptopodin expression in adult rats subjected to hypoxia on E14 compared to controls, p ≤ 0.05. No significant changes in PSD95 and synaptophysin can be seen n = 8 in each group of animals. (E) Electrophoretic separation of young (P30) rat cortical tissue proteins and subsequent immunoblotting against synaptopodin (100 kDa), PSD95 (95 kDa), and actin (45 kDa). (F) Ratio of the band intensity of the protein of interest (white, dotted columns—spine-associated protein synaptopodin, gray columns—the postsynaptic marker protein PSD95) to the actin band intensity in young (P30) rat cortical tissue. Data presented as mean optical density ratio ± SEM. Asterisk—significant difference in synaptopodin or PSD95 protein expression between control rats and rats exposed to hypoxia on E14 (two-tailed Mann–Whitney U-test with independent samples, p ≤ 0.05). No significant changes were shown in rats exposed to hypoxia on E18. N = 4 in each group of animals.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4814516&req=5

Figure 3: Expression and distribution of synapse-associated proteins in rat cortical tissue on P90. (A) Distribution of an actin-associated protein synaptopodin in the molecular layer of the parietal cortex, adult control rat. Scale: 10 μm. Indirect immunofluorescence, excitation—488 nm wavelength, emission—552–690 nm wavelength. (B) Number of labile synaptopodin-labeled dendritic spines in the molecular layer of the parietal cortex in adult rats (P90). Ordinate: number of synaptopodin-positive spines per 100 × 100 μm area. *Statistically significant changes compared to the control (p ≤ 0.001). (C) Immunoblotting of proteins from adult rat cortical tissue with antibodies against synaptopodin (100 kDa), PSD95 (95 kDa), synaptophysin (37 kDa), and actin (45 kDa). (D) Ratio of the intensity of the bands corresponding to the proteins of interest (white columns—spine-associated protein synaptopodin, gray columns—postsynaptic marker protein PSD95, dotted columns—presynaptic marker synaptophysin) to the intensity of the band of actin. Data presented as the mean ratio of optical density ± SEM. *Statistically significant decrease in synaptopodin expression in adult rats subjected to hypoxia on E14 compared to controls, p ≤ 0.05. No significant changes in PSD95 and synaptophysin can be seen n = 8 in each group of animals. (E) Electrophoretic separation of young (P30) rat cortical tissue proteins and subsequent immunoblotting against synaptopodin (100 kDa), PSD95 (95 kDa), and actin (45 kDa). (F) Ratio of the band intensity of the protein of interest (white, dotted columns—spine-associated protein synaptopodin, gray columns—the postsynaptic marker protein PSD95) to the actin band intensity in young (P30) rat cortical tissue. Data presented as mean optical density ratio ± SEM. Asterisk—significant difference in synaptopodin or PSD95 protein expression between control rats and rats exposed to hypoxia on E14 (two-tailed Mann–Whitney U-test with independent samples, p ≤ 0.05). No significant changes were shown in rats exposed to hypoxia on E18. N = 4 in each group of animals.
Mentions: The pattern of distribution of the actin-associated protein synaptopodin in control adult rats on P90 is given in Figure 3A demonstrating that the majority of this protein is located in dendritic spines (immunopositive dots, 1 μm in diameter) in the molecular layer of brain cortex. On the other hand, the immunolabeled postsynaptic protein PSD95 was mostly placed near the synaptophysin-positive presynaptic terminals in different (but mostly in the molecular) cortical layers.

Bottom Line: In control rat pups a majority of cells labeled on E14 were localized in the lower cortical layers V-VI while the cells labeled on E18 were mainly found in the superficial cortical layers II-III.In rat pups subjected to hypoxia on E18, the total number of labeled cells in the parietal cortex was also decreased but the number of scattered labeled neurons was higher in the lower cortical layers.Hypoxia on E18 does not significantly affect cortical structure and parietal cortex-dependent behavioral tasks.

View Article: PubMed Central - PubMed

Affiliation: I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of SciencesSaint Petersburg, Russia; Research Center, Saint-Petersburg State Pediatric Medical UniversitySaint Petersburg, Russia.

ABSTRACT
Long-term effects of prenatal hypoxia on embryonic days E14 or E18 on the number, type and localization of cortical neurons, density of labile synaptopodin-positive dendritic spines, and parietal cortex-dependent behavioral tasks were examined in the postnatal ontogenesis of rats. An injection of 5'ethynyl-2'deoxyuridine to pregnant rats was used to label neurons generated on E14 or E18 in the fetuses. In control rat pups a majority of cells labeled on E14 were localized in the lower cortical layers V-VI while the cells labeled on E18 were mainly found in the superficial cortical layers II-III. It was shown that hypoxia both on E14 and E18 results in disruption of neuroblast generation and migration but affects different cell populations. In rat pups subjected to hypoxia on E14, the total number of labeled cells in the parietal cortex was decreased while the number of labeled neurons scattered within the superficial cortical layers was increased. In rat pups subjected to hypoxia on E18, the total number of labeled cells in the parietal cortex was also decreased but the number of scattered labeled neurons was higher in the lower cortical layers. It can be suggested that prenatal hypoxia both on E14 and E18 causes a disruption in neuroblast migration but with a different outcome. Only in rats subjected to hypoxia on E14 did we observe a reduction in the total number of pyramidal cortical neurons and the density of labile synaptopodin-positive dendritic spines in the molecular cortical layer during the first month after birth which affected development of the cortical functions. As a result, rats subjected to hypoxia on E14, but not on E18, had impaired development of the whisker-placing reaction and reduced ability to learn reaching by a forepaw. The data obtained suggest that hypoxia on E14 in the period of generation of the cells, which later differentiate into the pyramidal cortical neurons of the V-VI layers and form cortical minicolumns, affects formation of cortical cytoarchitecture, neuronal plasticity and behavior in postnatal ontogenesis which testify to cortical dysfunction. Hypoxia on E18 does not significantly affect cortical structure and parietal cortex-dependent behavioral tasks.

No MeSH data available.


Related in: MedlinePlus