| Objective:In recent years, Magnetic Resonance Imaging(MRI) is developing very rapidly, which has been widely used in clinic and has received high recognition from the society. However, safety of MRI in pregnancy, is still one of the important concerns. Numerous studies show that MRI exposure in the second、third trimester of pregnancy (mainly fetal magnetic resonance) had no significant effect on the fetus. The early stage of embryonic development is the most important period of life, in which all tissues are highly sensitive to exogenous disrupting factors. It has been increasingly recognized that prenatal environmental exposures in this period can result in miscarriage、 intrauterine growth dysplasia and even lasting adverse health effects in adulthood.MRI uses three electromagnetic fields to produce images from inside the body, a static magnetic field, pulsed radio-frequency (RF) fields and time-varying gradient electromagnetic fields (EMF). The biological effects of the static and time-varying magnetic fields, the heating effects of the RF pulses and the acoustic noise generated by the spatial encoding gradients are the primary factors that may affect the development of embryo. There are numerous researches on the issue of safety of MRI during pregnancy.Although most of the results indicate that there is no harm or injury to the fetus, some animal studies have noticed malformations or other adverse outcomes such as reduction in fetal weights and crown-rump length、high postpartum death.But these studies are long past. The magnetic field intensity was low at the time,and few research utilizing clinically realistic exposure conditions.The outcome measures concentrated on the abortion rates, stillbirth rates, teratogenic rate and so on.These is no further research no the field of gene、RNA and protein. So far, there is not enough evidence to show that MRI is safe.In this study, we investigate if an in utero exposure during the first trimester of pregnancy with1.5T MRI utilizing clinically realistic exposure conditions has an adverse effect on embryo using two method-intrauterine growth and proteomic techniques.These analyses should provide deep insight regarding underlying mechanism on reproductive health.Methods:We randomly divided the E10.5mice to the15min/30min/60min exposure group and the sham exposure group. The exposure group scan15mim,30min,60mim using routine pelvic MRI sequence. They were sacrificed by cervical dislocation immediately after4hours, removing the embryos and extracting protein, then using TMT proteomic technology to find the different proteins between the exposure group and sham exposure group, and analyzing the function of these proteins.The fetuses were removed by caesarean section when full-term. Comparing the implantation number、gross weight、the gross placenta weight, the stillbirth rate、 absorbed fetus rate、teratogenic rate and the fetal weigh、crown rump length、tail length between the exposure group and sham exposure group.Results:1. There was significant difference between the exposure group and sham exposure group in protein profiles. Taking the ratio of greater than1.5or less than1/1.5as the screening threshold, the number of differentially expressed proteins between each group are shown below:15min-VS-15min control:31up-regulated proteins and147down regulated proteins;30min-VS-30min control:217up-regulated proteins and508down regulated proteins;60min-VS-60min control:280up-regulated proteins and392down regulated proteins.It showed that many protein expression appeared differences after MRI treatment. The down regulated proteins are much more than up-regulated protein. In three groups, there are no concomitant up regulated of protein, but2concomitant down regulated proteins. In15min and30min groups, there is1concomitant up-regulated protein,2concomitant down regulated proteins; In30min and60min group, there are4concomitant up-regulated proteins,24concomitant down regulated proteins; In15min and60min group, there are8concomitant up-regulated proteins,68concomitant down regulated proteins.2.To analysis the30min-VS-30min control proteins, we found it mainly involved in cell adhesion and connection, the utilization and synthesis of the carbon source, the metabolism and degradation of DNA and RNA, the precursor of the protein-amino acid metabolism and synthesis, the synthesis module of the protein and protein degradation and lipid synthesis, etc. More than10proteins which have the most significant difference were mainly involved in transport and signal transduction of cell material, metabolism of purine, RNA metabolism, fatty acid synthesis, etc.3.There was no statistically significant difference by comparing the implantation number、gross weigh、the gross placenta weight, the stillbirth rate、absorbed fetus rate、 teratogenic rate and the fetal weight、crown rump length、tail length between the exposure group and sham exposure group.Conclusion:It will cause the change of protein expression profiles of mouse early embryos under normal working conditions of1.5T MRI exposure for a certain period of time.There are great differences of the protein profiles in different exposure time; but the fetal intrauterine growth abnormalities were not found after exposure. |
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