Toxicity of ultrasound in mice: Neonatal studies

Abstract

Pregnant mice were exposed to ultrasound (continuous wave, 2 MHz) on Day 8 of gestation to determine effects on the progeny. The most significant finding was a decrease in mean uterine weight of the female progeny. The thresholds for this effect were 140 s at 0.5 W/cm2 and 60 s at 1 W/cm2, which were below the thresholds previously reported for other effects in mice. We suggest that this indicates a delay or impairment of maturation of the mice exposed in utero. Exposure of the dams to spatial average intensity of 1 W/cm2 for 40 and 60 s had no effect on body weight of the progeny, compared with sham-treated controls. In this experiment the body weights of progeny from sham-treated controls were significantly lower than those from untreated controls on Days 10, 17, and 25 of age. After exposure in utero to 0.5 W/cm2 for 180 s, statistically significant decreases in mean body weights of the neonates were observed, but only on Day 25 of age, in both sexes compared with sham-treated controls. At necropsy at Day 25 of age, neonatal organ weights relative to body weights were not significantly affected for the thymus in either sex or for the seminal vesicles and tests ion comparison with sham-treated controls.

Biological effects of high-frequency ultrasound exposure during mouse organogenesis

“…In this study, the maternal exposure was continuous insonation across the abdomen, whereas individual fetuses will not have the same degree of incessant exposure. Several previous studies may have been complicated by maternal distress or temperature elevation (Stolzenberg et al 1980a(Stolzenberg et al , 1980bKimmel et al 1983Kimmel et al , 1989Shoji et al 1975; reviewed in Barnett and Table 4. Calculated values for mean crown-rump length, body length and body weight of pups born to five pregnant females exposed to US and/or anesthetic at 10.5 embryonic days of gestation Age Cage control Anesthetic-exposed E10.5 B mode-exposed E10.5 Doppler-exposed E10.…”

Gestational stage sensitivity to ultrasound effect on postnatal growth and development of mice

“…Earlier reports suggested that if embryonic temperature does not exceed 398C, there might not be any measurable thermal risk produced (Brent et al, 1991). However, there are reports in which the temperature was increased in mice up to 438C and these authors concluded that ultrasound produced an indirect effect on the fetus by altering maternal tissues and/or function, and these effects were assumed to be mediated thermally (Stolzenberg et al, 1980b;Angles et al, 1990;Barnett and Willams, 1990;Kimmel et al, 2002). The extent of temperature rise may depend on the duration of exposure, mouse strain, and type and intensity of ultrasound.…”

“…Significantly low birth weight was observed in the present study, after exposure on days 11, 12, 14, and 16 p.c. Several reports on mice exposed to ultrasound reveal a significant reduction in body weight at birth (Stolzenberg et al, 1980b;Stratmeyer et al, 1981aStratmeyer et al, , 1984O'Brien, 1983). No such change in fetal weight and growth was found in earlier studies due to fetal exposures to ultrasound in mice (Warwick et al, 1970).…”

The combined effect of ultrasonic exposure and protein restriction on maternal and fetal mice

“…The increased use of ultrasonic energy in obstetrics dictates that a reliable assessment of its risks to human populations has to be performed. It has been shown that fetal weight depression does occur as a result of exposure to ultrasound during the prenatal period in certain mouse strains (O'Brien 1976 andStratmeyer et al 1977;Stoizenberg et al 1980a;Stolzenberg et aL 1980b). There is also evidence to show that maternal body weight is decreased from in utero ultrasonic exposure (Stolzenberg et aL 1980a) and that fetal weight reduction may be sustained post weaning (Stratmeyer 1981).…”