| Objectives:To make brain damage of intrauterine grow retardation(IUGR) rat model by feedingthe pregnant rats with low-protein (6%protein) diet. To observe the changes in brainstructure, physical growth in rats and the expression of myelin basic protein (MBP) inbrain after prenatal vitamin B12supplement.To discuss the influence of prenatal vitaminB12supplement on the brain development of IUGR rats.Methods:Fifty-six healthy three-month Sprague-Dawley rats were selected for the experiment,the male rat and female rats were put into the same cage according to the ratio of1:1. Thepregnant rats were divided into normal control group (CC) and IUGR groups (S) randomly,then the rats in IUGR groups were distributed into two groups such as SV and SC,basedon the supplements of prenatal vitamin B12or not. The rats in the control group weregiven21%of normal protein diet since the rats got pregnant; while the rats in IUGR groupwill be given6%protein diet to build IUGR model in the same condition. At the same time,the rats in SV, which is given6%protein diet will be supplied with vitamin B12150ug/dby gastric perfusion until delivery. The offspring rats were fed by maternal breastfeedingby the pregnant rats,who were given21%normal protein diet and running water. We chose1d,7d,14d and21d as for4different time points. In every time point, there were ten rats ineach group, we observe the offspring body weight, crown-rump length, brain weight andtake brain for study. For the brain samples, hippocampus structure was observed with HEstain method, while dynamics expression of myelin basic protein(MBP) in hippocampuswas observed with immunohistochemistry method and Western blot method. At the sametime,observe the expression level of VitaminB12(VB12) and homocysteine (Hcy) in serumby Elisa in offspring rats with each time point and the pregnant rats after childbirth. Results:1.The incidence of IUGR and perinatal mortality in three pups: compared with rats incontrol group (CC), the incidence of IUGR were higher(P <0.01), but there were fewdifferences between group SV and group SC(P>0.05); There were also few differences ofperinatal mortality among the three pups(P>0.05).2.The dynamics expression of body weight, crown rump length and brain weight forthree groups: At1d,compared with rats in control group (CC), the rats in IUGR groupwere thinner and shorter, and their body weight, crown-rump and brain weight was lower（P＜0.01）;It was the same condition in7days old and14days old (P<0.05). Aftercatch-up growth, at21d, there were no obvious differences between control group (CC)and IUGR group, SV and SC included (P>0.05),except brain wet weight (P<0.05). In theIUGR group, those indicators in SV were higher than those in SC at every time point, butthat differences had not much meaningful.(P>0.05).3.The differences in the organization structure of hippocampus:Compared with thecontrol group (CC), the neuronal cells located in the hippocampus from the rats in IUGRgroup were held the states such as loosely arranged, edema, vacuoles, nuclear condensation,and soon on. And the numbers of the neuronal cells decreased.When the rats were21daysold, these cell states were improved, except the numbers of neuronal cells.The conditionsof the neuronal cells in group SV were better than those in group SC.4.The dynamics expression of MBP in hippocampus tissue:According to theexperimental results, it was shown that the expression of MBP in hippocampus were notdetected until the rats was14days old. With time went by, the expression of MBP werehigher. Besides, the expression of MBP were distinct among the three groups at the sametime point. The CC group held the highest expression,followed by SV group, and thelowest one was SC group.5.The dynamics expression of serum vitamin B12and homocysteine (Hcy) inpregnant rats after childbirth and offspring rats: The expression of vitamin B12in CCgroup was lower than that in SV group (P <0.01) for the pregnant rats after childbirth, butit was higher than that in SC group.While the expression of Hcy showed the oppositetrend(P <0.05). With the time went by, the expression of vitamin B12in offspring ratswhich were from1day old to14days old decreased gradually, and it was also opposite inthe expression of Hcy. However, the differences between expression of vitamin B12and Hcy were not evident in21days old. As a whole, the contents of vitamin B12in SV groupwere higher than that in the CC group, and the SC group held the lowest expression level.it was still opposite in the expression of Hcy for the rats(P <0.05).Conclusions:1. The brain damage of IUGR rat model established by feeding6%low-protein dietduring pregnancy was reliable. The IUGR rats induced by were associated with decreasedbrain weight, the reduction number of neuronal cells in Hippocampus with looselyarranged.2. The IUGR rats who were given normal diet after birth could achieve catch-upgrowth, but the number of neurons, brain weight and the expression of MBP in brain tissuestill behind normal rats.3. VitaminB12supplementation during pregnancy could increase the expression ofvitamin B12, and decrease the expression of Hcy both in pregnant rats and offspring rats.4. VitaminB12supplementation during pregnancy could not the reduce the incidenceof IUGR, but it could improve the neurons shape in the hippocampus, increase bodyweight、crown rump length and brain weight and the expression of MBP, which maybeindicate that the brain damage caused by the IUGR condition can be ameliorated throughthe supplement of vitamin B12. |
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