Study On The Effects Of Ultrasound On Nervous System Of Fetal Rats And Neonatal Rats

First part : Study Of Ultrasound On Apoptosis Of Central Neurons In Fetal Rats. Objective: To study the effects of ultrasound on apoptosis of central neurons in fetal rats and to evaluate the safety of ultrasound.Methods:The first step:Twenty pregnant ICR rats were divided randomly into four groups:0-min group(control group),10-min group,20-min group,30-min group and randomized to receive ultrasound on 18d of gestation. In each group the cortical brain tissues of fetal rats were removed at 24th hour after exposure to ultrasound.The percentage of apoptosis was analyzed by flow cytometry(FCM).The second step:Twenty-five pregnant ICR rats were divided randomly into five groups.Control group was established without radiation.Rats in groupⅠ～Ⅳwere sacrificed at the 12th,24 th,48 th and 96th hour respectively.Pregnant rats were exposed to ultrasound for 30minutes. In each group the cortical brain tissues of fetal rats were removed.The percentage of apoptosis was analyzed by flow cytometry(FCM).Results:The first step: The percentage of apoptotic cells in control group, 10-min group,20-min group,30-min group was1.95%,2.10%,6.80% and 6.89% respectively.There were no siginificant differences between control group and 10-min group(P>0.05). There were siginificant differences between control group and 20-min group, 30-min group respectively(P<0.01).The second step: The percentage of apoptotic cells in control group,Ⅰgroup,Ⅱgroup,Ⅲgroup andⅣgroup wa2.00%,5.83%,7.05%,6.88% and 5.65% respectively. There were siginificant differences between control group andⅠgroup,Ⅱgroup,Ⅲgroup andⅣgroup respectively (P<0.01).Apoptosis cells increased at the 12th hour after exposure,reached peak at the 24th hour and decreased at the 48th hour.Conclusions: (1) Exposure to ultrasound over 20 minutes may result in cortical neurons apoptosis in fetal rats brain(.2)The time that exposure to ultrasound correlates significantly to apoptosis of central neurons. (3) The percentage of apoptosis can decrease gradually.Sencond part: The influence of ultrasound on learning memory of neonatal rats and the contents of acetylcholinesterase(ACHE) in the hippocampus.Objective: To investigate the influence of ultrasound on rats learning and memory and ACHE in hippocampus, and to evaluate the safety of ultrasound.Methods: The first part:twenty pregnant ICR rats were divided randomly into four groups:0-min group(control group),10-min group,20-min group,30-min group.The neonatal rats in each group were randomized to receive ultrasound on 14d of gestation. In each group neonatal rats were randomly selected to behavioral tests (thirty for Y-type maze)for learning and memory at thirty days.Rats that react hypersensitivity or too dully were...