| Acrylamide is an important chemical mainly used for the synthesis ofpolyacrylamide. The polyacrylamide is used in the industry fields such as defense,petrochemicals, water treatment, paper making, textile, scientific experiments and soon. Polyacrylamide itself has no toxicity. However, polyacrylamide contains littleamounts of monomer which pose a significant risk to human health. Previously,extensive experiments have shown that acrylamide has neurotoxicity, genotoxicity,carcinogenic toxicity in animals. However, only neurotoxicity has been found inhuamnbeings. At present,the literature on the neurotoxicity of ACR in the adultanimals is huge. The neurotoxicity of ACR mainly causes axonal neuropathy in thecentral and peripheral nervous system, which can produce ataxia, skeletal muscleweakness, and main pathological characteristics were distal axon swelling anddegeneration. Our previous studies had already proved that acrylamide could induceneurotoxic effects in rats.In2002, it was found that ACR is generated during heating of foodscontaining carbohydrate and asparagines, and risk assessment studies of ACR infoodstuffs are now being conducted globally. In2006, the64th FAO/WHO JointExpert Committee on food additives pointed out that mean daily intake of ACR foradults is estimated as1μg/kg/body weight/day. In fact, as the body weight of theinfants and children is much lower, but their consumption of snack foods like potatochips, biscuits and cream is far more than adults, so, intake of ACR for infants andchildren is estimated to be2-3-fold higher than for adults. Therefore, it is necessary for us to prove if the acrylamide will affect the neurodevelopment of the infant andchildren. However, the impact of ACR on the development of neurons in embryonicand lactating animal is not clear. Therefore, we carried out the research of the toxiceffect of sub-acute exposure to Acrylamide on the development of neuron inhippocampal of weaning rats.The purpose of this study was through the observation of the changes in thebody weight of rats exposed to acrylamide in gestation and lactation and theirmorphological changes of neuros in the hippocampus dentate gyrus after HE staining,assessment the expression of DCX and SYP in the neurons of hippocampus dentategyrus by using immunofluorescence histochemistry, assessment the expression ofBDNF and GAP-43in hippocampus by using western blot to explore the effects andthe possible mechanism of acrylamide on the development of neurons in thehippocampal of rats exposured to ACR during gestation.Method:1. The establishment of animal model:64adult SD rats,5-8weeks old (150-180g), were obtained from Experimental Animal central of Guangzhou. Femalescohabited with males in1:1ratio.The day of finding seminal plugs below thewire-bottom cage floor was defined as gestational day (CD)0. The day of deliveryday was defined as delivery（DD）0. The pregnant rats were divided into4groupsand each group consists of8. The control group was administrated with waterwithout acrylamide. The other3group rats were administered with acrylamidesolution of50ppm、100ppm、200ppm respectively from the CD0to DD21. From the3day of delivery，Litters were weighted and culled randomly to preserve8pups.2. The detection of general Physiological index about dams: Every week, werecorded the general growth index, including the consumption of feed, water and theweight. Besides, we calculated the dams daily intake of acrylamide.3. Assessment of maternal gait score: We observed the behavior of the damsevery day and calculated their gait score once week during the dosage period.4. Observation of growth in pups: We observed the general growth statement ofthe pups and mesure their body weights each week. 5. Morphologic observation of the hippocampal neuron in weaning rats: Weobserved the morphology changes of the hippocampal neuron in weaning ratsthrough HE staining.6. DCX and SYP assays. By using immunofluorescence Technique, we assessedthe expression of DCX and SYP in hippocampal neuron of the weaning rats.7. BDNF and GAP-43assays. By using the western blot, we assessed theexpression of BDNF and GAP-43in hippocampal neuron of the weaning rats.8. Data Analysis. Statistical analysis was carried out using spss16.0.All datawere expressed as means±SEM. The matanal gait scores were analyzed by MannWhitney U Test, other data were processed by mono factor analysis of variance. Ifthe differences between groups are significant, then all the data compared betweengroups by LSD. If α=0.05.values of P<0.05were regarded as significant.Results:1．The effects of ACR on the dams: Body weight, food consumption and waterconsumption were significantly lower in the experimental group when comparethose of the control group. At the end of exposure, the dams in100ppm group and200ppm group were mild and moderate to severe neurological damage respectively.2．The effects of ACR on the growth of offspring: The offspring’ body weight atthe delivery day is significantly lower in the experimental groups when compare tothose of the control group. At the end of lactation, body weight loss was correlatedwith the acrylamide lever, the higher acrylamide lever is,the lower the body weightis(50ppm=96.25%，100ppm=81.07%，200ppm=62.34%，P<0.01)3．Results of HE staining: There were no significant morphological changes ofneurogenesis in dentate gyrus of hippocampus of the50ppm group. As high as theacrylamide is, the morphological changes are more significant. The arrangementabout the neurogenesis in dentate gyrus is much loser, the number of the nerve cellsare less, the karyopyknosis between the granular layer and sub-granular layer aremuch more significant in the experimental group when compare it to those of thecontrol group. The higher the acrylamide lever is, the morphological changes are. 4．The result of immunofluorescence histochemistry: We can find out the DCXpositive immune reaction substance in the neurogenesis’ body and axon both in thegranular layer and the dentate gyrus. The DCX positive substance is round or comb.The mean optical density of neurogenesis with the DCX positive immune reactionsubstance is much more significant in the100ppm group compare to those of thecontrol group(P<0.05). Besides, this index of200ppm group is much moresignificant while compare to the control group (P<0.01). SYP positive immunereaction substance is mostly located in the dentate gyrus, The mean optical densityof neurogenesis with the SYP positive immune reaction substance is much moresignificant in the100ppm group compare to those of the control group(P<0.05).Besides, this index of200ppm group is much more significant while compare to thecontrol group (P<0.01).5． The result of western blot: BDNF and GAP-43are express in thehippocampus of all immature rats. However, the BDNF and GAP-43level are muchlower in the100ppm group compare to those of the control group and50ppmgroup.(P<0.05). Besides, this index of200ppm group is much more significantwhile compare to the control group (P<0.01).Conclusion:1. ACR matanal exposure can lead the body weight of offspring to bedecreased in birthday and depressed during lactation.2. Exposued to ACR in gestation and lactation can decrease the expression ofDCX, SYP, BDNF and GAP-43in the hippocampus of rats,and then affecthippocampal neuronal development.3. Neuronal proliferation, differentiation, migration, synaptic formation maybe involved in the impact of the development of neurons in the hippocampal ofweaning rats subacutely exposured to ACR. |
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