Expresssion Of Nerve Growth Factor And Brain-derived Neurotrophic Factor In Hippocampus Of IUGR Fetal Rats

Objective: The rat model of intrauterine growth retardation (IUGR) was established by low-protein diet in the time of pregnancy. To study the expression of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in the hippocampus with different stages of IUGR fetal rats'brain, and to explore the mechanism of cognitive dysfunction of IUGR. Providing relevant evidence to the early intervention for IUGR.Methods:The experimental animals are age-appropriate (70-90days) SD rats. All the SD rats are respectively fed by low-protein and normal-protein diet. With the judgment standard of IUGR, all the IUGR fetal rats from low-protein diet group are devided into Oday, lOday,30day group. All the normal fetal rats from normal-protein diet group are devided into Oday,10day,30day group. Respectively, measuring IUGR fetal rats and control fetal rats'body quality and brain quality in the0day,10day,30day time by using electronic balance analyzer.Using the method of immunohistochemical and computer image analysis technique to observe the change of the NGF and BDNF's expression in the hippocampus of fetal rats. Meanwhile,using microscopy to observe the pathological changes of hippocampus.Results: l.Still brith rate:The still birth rate of the low-protein diet group was17.95%(14/78).Normal-protein group's still brith rate was5.00%(4/80).The differences between low-protein diet and normal-protein group was significant(P<0.05).2.The low-protein and the normal-protein group fetal rats'body quality respectively were4.897±0.430,6.165±0.560. The birth quality of low-protein diet group is significantly lower than normal-protein group(p<0.05).3.The incidence rate of IUGR:The IUGR incidence rate of the group with low-protein diet during pregnancy was62.50%(40/64), were significantly higherly than control group(7.89%;6/76)(p<0.05).4. Body quality:All fetal rats'body quality was measured by electronic balance analyzer.The0day's IUGR and the0day's control group fetal rats'body quality respectively were4.685±0.313,6.435±0.314. The difference was n statistically significant (P<0.01).10day's IUGR group and control group fetal rats' body quality respectively were16.880±1.106,17.889±1.270.30days IUGR group and control group fetal rats'body quality respectively were64.755±2.440,65.376±2.848. The difference was not statistically significant(P>0.05).5. Brain quality:The IUGR and control group fetal rats'brain quality respectively were0.183±0.016,0.227±0.032,10days'IUGR group and control group fetal rats'brain quality were0.709±0.022,0.814±0.029,30days'IUGR group and control group fetal rats'brain quality respectively1.168±0.023,1.295±0.025. All the difference was statistically significant (P<0.01).6.The hippocampus'morphological observation: We found that the neurons in the hippocampus of IUGR group's fetal rats arranged disorderly and swelled. The nucleolus can't seen clearly.7. The expression of NGF and BDNF in the hippocampus:The levels of NGF in hippocampus of IUGR fetal rats,were obviously lower than the control group's in the0,10,30day time(p<0.05). The levels of BDNF in hippocampus of IUGR fetal rats were less lower than the control group's in the0day time(p>0.05).In the10days'and30days'group,the expression of BDNF in hippocampus of IUGR fetal rats were slightly higher than the control group's (P>0.05)Conclusion:1. The IUGR experimental animal model was successfully established by low protein diet.2.We found that the expression of NGF in IUGR group's hippocampus was low, which continued to the30day(equal with8years in human).The low expression of NGF may be relevanted with cognitive dysfunction of IUGR. Meanwhile the BDNF's expression in IUGR did not bring down,which may be relevanted with IUGR'S brain protection effect.3.All the fetal rats were fed by normal diet and we found that IUGR fetal rats'body quality appeared catch-up growth. But the brain quality is still not recoved in the time30day.