Effect of fetal exposure to ultrasound on the behavior of the adult mouse

Pregnant Swiss albino mice were exposed to diagnostic ultrasound (3.5 MHz, 65 mW, I(SPTP) = 1 W/cm², I(SATA) = 240 W/cm²) for 10, 20 or 30 min on day 14.5 (fetal period) of gestation. Sham-exposed controls were studied for comparison. Any changes in physiological reflexes (such as pinna detachment, opening of the eyes and development of fur), postnatal mortality and changes in adult behavior (open-field test, dark/bright arena test, hole board test and conditioned-avoidance test) were recorded. No change was observed in the physiological reflexes. The postnatal survival was also not affected significantly by the exposure. However, there were significant alterations in behavior in all three exposed groups as revealed by the decreased locomotor and exploratory activity and the increase in the number of trials needed for learning. These results indicate that ultrasound exposure during the early fetal period can impair brain function in the adult mouse.