Effects of Prenatal Exposure to MRI Magnetic Field
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RESEARCH ARTICLES
Effects of Prenatal Exposure to MRI Magnetic Fields on Protein Expression of Glutamate Receptors in the Hippocampal Formation of Rats?
Mali Jiang, Taizhen Han??, Dongwei Yang, Wen Xie
Abstract: This present study investigated the effects of prenatal exposure to the magnetic resonance imaging (MRI) magnetic fields on protein expression of NMDA receptor subunits NR1, NR2B and AMPA receptor subunit GluR1 in rats' hippocampal formation at different stages of postnatal development. Pregnant rats on gestation of the 12th-18th days were exposed to the magnetic fields used for MRI applications. When the female offspring were 1, 2, and 5-month-old, the SP immunohistochemical staining was made in the paraformaldehyde fixed hippocampal sections. Computer-assisted image was taken for analysis. Compared with the control group, the MRI group showed a significant increase of NR1 immunoreactivity in the hippocampal CA1 region and an increasing tendency in the hippocampal CA3 area at the age of 5 months. No significant effect was detected at the age of 1 and 2 months in the hippocampal formation. No significant difference was observed between the two groups in NR2B and GluR1 subunits at all the ages. The results indicate that prenatal exposure to the MRI magnetic fields induces changes of NMDA receptors in the hippocampus of mature brain.
Key words: prenatal exposure delayed effects; MRI; NMDA receptor; AMPA receptor; hippocampal formation
Scientific researches reported that the central nervous system (CNS) is particularly susceptible to magnetic fields (MFs) [1, 2], which can markedly affect neural electrophysiological and biochemical activities [3, 4]. Exposure to MFs increases the risk of inducing neurodegenerative diseases in humans [5] and producing deficits in spatial leaning in rats [6]. Therefore, the public concern about the safety of exposure to MFs is increasing. Magnetic resonance imaging (MRI) has been used in studying fetal development [7, 8] and assessing brain injuries [9], due to its high capacity of visualizing the brain structure. However, whether prenatal exposure to MRI affects the developmental brain is still not clear. Our previous study indicated that prenatal exposure to the MRI magnetic fields not only caused cognitive/behavioral deficits but also induced synaptic ultrastructural changes [10, 11]. The present study investigated the influences of periodic exposure of pregnant rats to MRI magnetic fields on the offspring's immunohistochemical expression of N-Methyl-D-Aspartate (NMDA) receptor subunits NR1, NR2B and α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit GluR1 in the hippocampal formation at different postnatal ages.
MATERIALS AND METHODS
1. Subjects and exposure
Fifteen healthy pregnant female Sprague-Dawley rats were used in the present study. The time of exposure to MFs or sham condition started from the 12th to 18th day of gestation. Randomly selected 8 of these pregnant rats were exposed to the MRI field for 7 consecutive days with 40 min a day ......
RESEARCH ARTICLES
Effects of Prenatal Exposure to MRI Magnetic Fields on Protein Expression of Glutamate Receptors in the Hippocampal Formation of Rats?
Mali Jiang, Taizhen Han??, Dongwei Yang, Wen Xie
Abstract: This present study investigated the effects of prenatal exposure to the magnetic resonance imaging (MRI) magnetic fields on protein expression of NMDA receptor subunits NR1, NR2B and AMPA receptor subunit GluR1 in rats' hippocampal formation at different stages of postnatal development. Pregnant rats on gestation of the 12th-18th days were exposed to the magnetic fields used for MRI applications. When the female offspring were 1, 2, and 5-month-old, the SP immunohistochemical staining was made in the paraformaldehyde fixed hippocampal sections. Computer-assisted image was taken for analysis. Compared with the control group, the MRI group showed a significant increase of NR1 immunoreactivity in the hippocampal CA1 region and an increasing tendency in the hippocampal CA3 area at the age of 5 months. No significant effect was detected at the age of 1 and 2 months in the hippocampal formation. No significant difference was observed between the two groups in NR2B and GluR1 subunits at all the ages. The results indicate that prenatal exposure to the MRI magnetic fields induces changes of NMDA receptors in the hippocampus of mature brain.
Key words: prenatal exposure delayed effects; MRI; NMDA receptor; AMPA receptor; hippocampal formation
Scientific researches reported that the central nervous system (CNS) is particularly susceptible to magnetic fields (MFs) [1, 2], which can markedly affect neural electrophysiological and biochemical activities [3, 4]. Exposure to MFs increases the risk of inducing neurodegenerative diseases in humans [5] and producing deficits in spatial leaning in rats [6]. Therefore, the public concern about the safety of exposure to MFs is increasing. Magnetic resonance imaging (MRI) has been used in studying fetal development [7, 8] and assessing brain injuries [9], due to its high capacity of visualizing the brain structure. However, whether prenatal exposure to MRI affects the developmental brain is still not clear. Our previous study indicated that prenatal exposure to the MRI magnetic fields not only caused cognitive/behavioral deficits but also induced synaptic ultrastructural changes [10, 11]. The present study investigated the influences of periodic exposure of pregnant rats to MRI magnetic fields on the offspring's immunohistochemical expression of N-Methyl-D-Aspartate (NMDA) receptor subunits NR1, NR2B and α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit GluR1 in the hippocampal formation at different postnatal ages.
MATERIALS AND METHODS
1. Subjects and exposure
Fifteen healthy pregnant female Sprague-Dawley rats were used in the present study. The time of exposure to MFs or sham condition started from the 12th to 18th day of gestation. Randomly selected 8 of these pregnant rats were exposed to the MRI field for 7 consecutive days with 40 min a day ......
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