Effects Of Prenatal Exposure To Static Magnetic Field On The Development In Chick Embryos And Learning In Chicks

Objective: The research aimed to study the effects of prenatal exposure to staticmagnetic field on growth and development in chick embryos and learning in chicks bymeans of incubating embryos under static magnetic field, and to study the mechanismhow static magnetic field exposure during embryonic period affects the learning andmemory cognition in the offsprings with detecting the expression of NMDA receptorNR1and NR2, BDNF, JUN and SYN， so as to provide theoretical foundation andsolutions for the radiation protection of static magnetic field in the future.Method: Permanent magnets were used to create static magnetic field environment(5mT and10mT), and the chick embryos were exposed in them until they hatched.The chick embryos of control group were hatched under normal conditions at the sametime. One-trial passive avoidance learning test was used after they hatched in24h and48h，and detour learning test was used after they hatched in9and15d to detect theharming effects of static magnetic field on cognitive ability in neurobehavior. Inaddition, take the brain tissue of each chick embryo to extract RNA at post hatch day8and15, as well as before and after one-trial passive avoidance learning test. Then detectthe expression level of NMDA receptor subunit NR1and subunit NR2of post hatch day8and15with RT-PCR, and detect the expression level of BDNF, JUN after the chickshatched in24h，as well as BDNF, JUN and SYN gene before and after one-trial passiveavoidance learning with qRT-PCR.Results:(1) The weight of the SMF exposure groups had no difference with thecontrol group except the weight and the hatch day of5mT SMF exposure group werelarger and shorter than the control group with significant difference （p <0.05） andextremely significant difference (p <0.01) after the chicks hatched, respectively.What’s more, there is no difference on incubation period and hatchability, either.(2)The avoidance rate of5mT and10mT were lower than the control group in one-trial passive avoidance learning test, furthermore, the time they used in detour learning werelonger than the control group (p <0.05).(3) At post hatch day8and day15, theexpression level of NR1and NR2in experiment groups were lower than the controlgroup with significant difference (p <0.05), especially the10mT group with significantdecrease.(4) The expression of BDNF and JUN were lower than the control group withsignificant difference (p <0.05);(5) The expression of BDNF、JUN and SYN presentedsame tendency before and after one-trial avoidance passive learning. Namely,5mT and10mT were all lower than the control group with extremely significant difference (p <0.01) or significant difference (p <0.05).Conclusion: Long time exposure to5mT or10mT static magnetic field duringembryonic period has effect on the chicks’ learning cognition and the expression levelof NMDA receptor、BDNF、JUN and SYN. NMDA receptor gene, as well as BDNF、JUNand SYN gene may be the important target in magntic field effecting nervous systemdevelopment of embryos and their offsprings’ cognitive ability.