| Objective: Lead is one of the most common chemicaltoxicants. Many people exposure to lead with high frequencyand their health are hurt. Recent studies show that lead exposurein gestation period can affect the health of the pregnant womanand their pups. So the study that how to degrade the toxicity oflead has been reconstructed. Selenium is an essential peroxidase(GSH-PX) and it have the protection to the damage of the body.So with the knowledge of selenium deeply, many researchesfocus on the protection of selenium against the toxicity of lead.We investigated the protective effect of various doses ofselenium on lead-induced placenta damage of pregnant rats andthe sex-differentiation, the growth and development and theinitiation of puberty of the pup rats. We hope to provide theevidence for the fittest dose which the selenium's antagonisticaction to the lead toxicity in the pregnancy.Methods: 1.60 healthy pregnant rats were divided into 5 groupsrandomly. Rats in every group were twelve and freelyadministered with drinking distilled water contained 2 mg/rnllead acetate, 2 mg/ml lead acetate+ 2μg/ml sodium-selenite, 2mg/ml lead acetate+4μg/ml sodium-selenite, 2 mg/ml lead acetate+ 8μa g/ml sodium-selenite till parturient, then drinkdistilled water and suckled till postnatal day (PND)21. Distilledwater was given at the same dosage in control group all timeand they suckled till postnatal day (PND)21.All groups atenormal fodder during experimental session.1. In gestation day 20, every pregnant rats were detected theblood lead, blood selenium and serum alkaline phosphates. Andtaked four pregnant rats randomly from every group, theiralkaline phosphates of placenta were detected byimmunohistochemistry technique, the morphological changes ofplacenta were observed with transmission election microscopeand microscope.2. After the other pregnant rats spontaneous delivery,all pup rats were detected, including body weight at PND1 andPND21,sex-differentiation, anogenital distance (AGD) and thesurvival rate at PND4and PND21.3. Take 12 pup rates randomly from every group in PND21,the weight of their didymus, epididymal, uterine and ovarianwere weighed. Subsequently, the VO and PPS of the other puprates were observed.4. All data were analyzed with spss11.0 soft ware,including Dunnett's test, X~2-test.Result: compared with control group, the alkaline phosphatasewas obviously higher in LT group, LA group and HA group, ithad significant statistical difference. But there was nosignificantly difference between MA group and control group. 1 compared with control group, the content of bloodlead in LT group and LA group had significant statisticaldifference. But there was no significantly difference among theMA group, HA group and control group. There was nosignificantly difference in the content of the blood seleniumamong all groups.2 Compared with control group, the weight of the puprats in PND1 in LT group decreased significantly, it hadsignificant statistical difference.3 There was no significantly difference in thesex-differentiation among all groups.4 There was no significantly difference in the AGDamong all groups.5 Compared with control group, the weight of thePND1 and the survival rate at PND4 and PND21 of the LTgroup decreased significantly, it had significant statisticaldifference.6 Compared with control group, the pup rats' weight inPND 21 of the LT group, LA group and HA group decreasedobviously, it had significant statistical difference.7 Compared with control group, the weight of the puprats' didymus and epididymal in PND21in LT group, LA groupand HA group decreased obviously, it had significant statisticaldifference.8 Compared with control group, the weight of the puprats' ovarian in PND 21 in LT group decreased obviousely, it had significant statistical difference.9 There was no significantly difference in weight ofthe pup rats' uterine among all groups.10 Compared with control group, the secondgenerations' VO in the LT group, LA group and HA group waspostponed up to 3.2-5.2 days, it had significant statisticaldifference.11 Compared with control group, the secondgenerations' PPS in the LT group, LA group and HA group waspostponed up to 2.6-4.4 days, it had significant statisticaldifference.12 There was no significantly difference in the secondgenerations' weight when they were VO or PPS among allgroups.13 Morphologically observation: observing minutestructure by the light microscope, compared with control group,the placenta cells of the LT group and HA group have hydroid orvacuolar degeneration phenomenon to some extent, and it wasalso found the hydroid structure in the interstitial substance inthe LT group and HA group; observing by the electronmicroscope, placenta cells in the LT group and HA group showthat vacuolization, broaden or degeneration of the roughendoplasmic reticulum, hydroid or decrease of the crista of themitochondria, some crista were arranged disorderly, evenphenomenon of confluence or disappearance; compared withcontrol group, the morphological damage of the LT group and HA group was the most obviously, and there was very similarbetween the MA group and the control group.Conclusion:1 Lead-touched in gestation period could damage the placentaand effect the growth and development of the second generation.2 Eligible Selenium nutritional supplement could rivaled thelead-intoxicated on the placenta and the second generation.3 Selenium possess bidirectional biological effect and confinedphysiological need, we should formulate the safe individualselenium nutritional supplement according the pregnant'sselenium level.
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