Developmental exposure of mice to pulsed ultrasound

Abstract

Exposure of pregnant mice on gestation day (gd) 8 to 1 MHz continuous-wave ultrasound (0, 0.05, 0.50, or 1.00 W/cm2) was reported previously to result in a slight (nonsignificant) increase in malformations. The present study was conducted in a similar fashion using pulsed ultrasound but was designed to maximize the likelihood of finding effects of gd 8 ultrasound exposure on prenatal development. Pregnant ICR mice (approximately 60 animals/group) were exposed on gd 8 to pulsed ultrasound with a center frequency of 1 MHz at levels of 0 (sham control), 0.05, 0.50, or 1.00 W/cm2 (spatial average, temporal average intensities; ISATA) with a spatial peak, pulse average intensity (ISPPA) of 90 W/cm2 and pulse duration of 6.5 microseconds. Anesthetized animals were placed in a degassed water bath (30 degrees C) and exposed for two 10 min intervals during which the beam was centered 1 cm on either side of the abdominal midline. On gd 17, dams were killed; the uterus and its contents were weighed and examined; and live fetuses were weighed and examined for external, visceral, and skeletal malformations. Although one female in the 0.50 W/cm2 group and seven animals in the 1.00 W/cm2 group died following exposure, no other significant change from controls was seen in any maternal or fetal parameter evaluated. Thus the results of this study indicate that there was no detectable effect on prenatal development of mice following exposure to ultrasound on gd 8 (a time of maximal sensitivity), even at exposure intensities that were lethal to some maternal animals.

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

“…Kimmel et al (1989) did not find any such malformations. In the present study exposure during either the organogenesis or fetal periods also did not produce any externally detectable malformations in the offspring.…”

“…Experimental efforts to delineate the biological effects of ultrasound on in utero development have been inconclusive. Some studies have reported increased malformation rates (Stolzenberg et al, 1980a;Saravazayan et al, 1982;Takabayashi et al, 1985), while others have found no such effects (Kimmel et al, 1983(Kimmel et al, , 1989Gates, 1984, 1985;Child et al, 1984Child et al, , 1989Vorhees et al, 1991;Jensh et al, 1994). Furthermore, there are conflicting reports concerning the effects of ultrasound exposure on body weight and behavioral changes (Stewart et al, 1985;Hendrickx, 1989a, 1989b;Norton et al, 1991;Hande and Uma Devi, 1992, 1993Newnham et al, 1993;Vorhees et al, 1994;Uma Devi et al, 1995;Fisher et al, 1996;Suresh et al, 1996).…”

How safe is it to use ultrasound in prenatal medicine? Facts and contradictions – Part 2 – Laboratory experiments regarding non-thermal effects and epidemiological studies

“…Kimmel et al [22] also insonated pregnant mice with intensities of up to 1 watt/cm² (SPTA). The fetuses were removed and examined on the 17th day.…”