Effects Of Prenatal And Postnatal PFOS Exposure On Nerve Growth Factor And Its MRNA Expression In Cortex Of Neonatal Rats

IntroductionPerfluorinated compounds(PFCs)have been detected in environment,wildlife and human samples collected from all over the world.Exposure to PFOS affects the liver primarily and causes vacuolation and hypertrophy of hepatic cells.PFOS decreases body weight(BW),serum cholesterol and triglycerides and increases liver weight.Recently,the developmental toxicities of PFOS have caused much more attention, prenatal exposure can affect growth and development of neonates,cause the ascending of morbidity and mortality and the happen of birth defects.NGF have since been shown to control many aspects of survival,development and function of neurons in both the peripheral and the central nervous systems,and its level was shown to change in many diseases in which cognition was affected.The purpose of this study was to investigate the accumulation of PFOS in neonatal rats under different exposure modes,as well as the effects in NGF and its mRNA levels. The learning and memorizing abilities of neonatal rats under different exposure modes were also identified.Methods and Materials1.Animals and treatmentGiven amount of PFSO-K was added into 2%Tween 80 solution,and then was added to powder feed,dried for use.Those animals with spermatozoa in a vaginal smear and/or with a copulatory plug were considered to be at gestation day.Animals were housed individually in polypropylene cages with heattreated pine shavings for bedding and were provided powder feed and tap water ad libitum.Animal facilities were controlled for temperature (20-24℃)and relative humidity(40-60%),and operated under a 12-h light-dark cycle. Once the neonates were born,half of them were exchanged from original dams to different groups.Cortexes were obtained on PD1,PD7,PD14,PD21,PD28 and PD35, and were stored at -70℃.2.Methods(1)Water maze assay(2)Detection of PFOS in neonatal cortex:HPLC/MS-SIM(3)Detection of NGF mRNA levels:RT-PCR(4)Detection of NGF protein:ELISA3.StatisticsThe data was set to mean±SE.Changes in every array were analyzed by analysis of variance(ANOVA)followed by Fisher's least significant difference(LSD)by SPSS 13.0.Comparison between two groups was done with t-test.Results1.Accumulation of PFOS in neonatal cortexContinuous exposure since prenatal period:PFOS concentrations of LL and HH groups were higher than that of CC group,and HH higher than LL.Postnatal exposure:PFOS concentrations of CL and CH groups were higher than that of CC group,and CH higher than CL.Prenatal exposure:PFOS concentrations of LC and HC groups were lower than those of LL and HH groups,respectively.And they were both higher than that of CC group.2.Levels of NGF mRNA under different exposure modesContinuous exposure since prenatal period:levels of NGF mRNA peaked on PD21. NGF mRNA level of LL group was higher than that of CC group on PD14,while NGF mRNA level of HH group was higher than that of CC group on PD1,PD14 and PD21.Postnatal exposure:NGF mRNA levels of CL and CH groups were higher than that of CC group on PD21 and PD28,respectively,but lower than that of CC group on PD35.Prenatal exposure:NGF mRNA levels of HC group was higher than that of HH group on PD28,NGF mRNA levels of LC group was higher than that of CC group on PD14,HC higher than CC on PD14 and PD28.3.Levels of NGF protein under different exposure modesContinuous exposure since prenatal period:NGF protein level of LL group was lower than that of CC group on PD14,while higher on PD28 and PD35.NGF protein level of HH group was lower than that of CC group on PD1 and PD14,but higher on PD35.Postnatal exposure:NGF protein level of CH group was lower than that of CC group on PD14,while higher on PD28.Prenatal exposure:NGF protein level of HC group was higher than that of HH group on PD14,and LC higher than CC on PD21 and PD35,HC higher than CC on PD1 and PD14.4.Latency of neonates under different PFOS exposure modesContinuous exposure since prenatal period:latency periods of LL and HH groups were longer than that of CC group.Postnatal exposure:latency periods of CL and CH groups were higher than that of CC group.Prenatal exposure:latency period of HC group was lower than that of HH group. Latency period of LC group was higher than that of CC group.Conclusions1.PFOS exposure of different modes can all cause accumulation of PFOS in neonates cortexes,abortion of exposure after birth can reduce the accumulation,but still above normal level.2.PFOS exposure of different modes can all lower NGF levels in the earlier period after birth,however a compensational rising was found in the latter period. mRNA levels were rising under different exposure modes.3.PFOS exposure of different modes can affect the learning and memorizing ability of neonates,abortion of exposure after birth can insert some rescue effects.