Abstract
Prenatal exposure to ultrasound may cause cognitive impairments in experimental animals;
however, the exact mechanisms remain unknown. In this study, we exposed pregnant rats
(or sham-exposed controls) to different intensities of ultrasound repeatedly on days
6, 12 and 18 of pregnancy for 4 min (3.5 MHz, spatial peak time average intensity = 7.6 mW/cm2, mechanical index = 0.1, thermal index bone = 0.1: 4-min group) or 20 min (3.5 MHz,
spatial peak time average intensity = 106 mW/cm2, mechanical index = 1.4, thermal index bone = 1.0: 20-min group). The Morris water
maze was used to assess learning and memory function in pups at 2 mo of age. Noticeable
deficits in behavior occurred in the group exposed to ultrasound for 20 min. Using
real-time polymerase chain reaction and Western blot, we also determined that both
the mRNA and protein expression levels of hippocampal N-methyl-D-aspartate (NMDA) receptor units 1 (NR1) and 2B (NR2B) and brain-derived
neurotrophic factor (BDNF) were significantly lower in pups exposed to ultrasound
for 20 min than in controls. Furthermore, the morphology of the synapses in the hippocampus
was partially damaged. Compared with the control group, the 4-min group had better
spatial learning and memory abilities, as well as higher mRNA and protein levels of
NR1, NR2B and BDNF. Our study suggests that high-intensity ultrasound irradiation
can decrease learning and memory abilities by reducing the expression of NR1, NR2B
and BDNF in the hippocampal regions and damaging the structure of synapses. In contrast,
low-intensity ultrasound irradiation can enhance the learning and memory abilities
of the offspring rats by increasing the expression of NR1, NR2B and BDNF receptor
in the hippocampal regions.
Key Words
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Article info
Publication history
Published online: January 28, 2015
Accepted:
September 2,
2014
Received in revised form:
August 23,
2014
Received:
February 9,
2014
Identification
Copyright
© 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
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- “Erratum to: “Prenatal exposure to ultrasound affects learning and memory in young rats,” by Li Ping, Wang pei-jun, Zhang Wei. Ultrasound Med Biol 2015;41:644-653Ultrasound in Medicine and BiologyVol. 41Issue 10
