The Joint Effects Of Calcium And Selenium On The Growth And Gevelopment Of Lead-intoxicated Rats

Lead is a kind of chemical toxicant which is commonly found in the environment.It can harm our health especially for younger generation. Lead can enter into ourhuman body through all kinds of ways, long-term lead exposure can lead toaccumulation in the human body and thus do harm to our bodies. Lead can also enterinto baby body through placenta and milk, babies are hypersensitive to lead for theblood and brain barrier are developing, the harm which was caused by lead isirreversible. These years the lead poisoning has become the center of the research. Itis reported that some nutrients can prevent lead from harming us, but the effect ofsingle nutrient such as calcium or selenium on lead is limited and many researcheshave already been done on it .Maybe now it is the time to pay much attention on thejoint effects of two nutrients on the lead. Calcium and selenium are necessaryelements for our human bodies, selenium is an important part of glutathioneperoxidase (GSH-PX), and can protect us from being harmed. Calcium is also veryimportant for our bodies. The research was conducted to reduce the harm and promotethe ability to excrete lead.ObjectiveOur objective is to find whether the joint use of calcium and selenium is moreeffective in reducing lead poisoning than single nutrient, calcium or selenium or not.Subjects and methods 1.96 three-week-old Kunming-class common rats, which weigh from 18 to 22grams, were divided into 8 groups randomly, there are 6 male and 6 female in everygroup, they were given the standard feed freely from the beginning of the research.The control group and the lead-model trial group were fed on the steamed water whileother groups were fed on the lead solution (Pb²⁺546mg/L). Our experiment lasted for20 days, the rats were perfused with the corresponding solution every two 2 daysaccording to the weight of the rats (2ml per 100grams body weight), on the 20th day,all the rats were killed to test the lead level of blood, main organs like brain,liver,kidneys,spleen,lungs and bones and the contents of NO and the activity NOS andiNOS of serum and brain after the labyrinth experiment was conducted. The contentsof the nutrients are as followed: 1,000mg/kg ? bw in the high-calcium group and200mg/kg in the low-calcium group (according to the calcium contents of calciumelement), 400μg/kg in the high-selenium group and 80μg/kg in the low-seleniumgroup (according to the calcium contents of selenium element), according to therelated articles. The details are as followed:Lead-model group Pb²⁺+dehydronium waterNormal control group dehydronium waterEDTA control group Pb²⁺+EDTA 12.9mg/kgHigh-calcium group Pb²⁺+1000mg/kg Ca²⁺High-selenium group Pb²⁺+400μg/kg Se²⁺High-calcium-and-high-selenium group Pb²⁺+1000mg/kg Ca²⁺+400μg/kg Se²⁺High-calcium-and-low-selenium group Pb²⁺+1000mg/kgCa²⁺+80μg/kg Se²⁺High-selenium-and-low-calcium group Pb²⁺+400μg/kg Se²⁺+200mg/kg Ca²⁺2.Every week the weight of the rats are tested and recorded to observe thegrowth and development of the rats. The following indexes were tested on the 20daysafter the labyrinth-escaping experiment:1.the blood lead contents and weights of the rats before the experiment,2.the blood lead contents and weights of the rats on the 20th day,3.the lead contents of blood,brain,liver,kidneys,lungs and bones,4.the contents of NO and the activity NOS and iNOS of brain 5.the labyrinth-escaping times3.Analysis of the data: input, audit data through Epidata and analyze the data bySPSS 12.0.Results1.There were no difference between the mean weights of every groups before theexperiment (F=2.62, P＞0.05). On the 20th day, the mean weight of the lead-modelgroup was lower than that of the rest 7 groups, respectively(P＜0.01), the meanweights of the five nutrient groups, EDTA group were lower than that of the normalcontrol group(P＜0.05), the mean weights of the three joint nutrient groups werehigher than that of the calcium group (P＜0.05), the mean weight of the three jointnutrient groups were higher than that of the selenium group(P＜0.05), the meanweights of the calcium group,selenium group were lower than that of EDTAgroup(P＜0.05)2.There were no difference between the mean blood lead levels of every groupsbefore the experiment(F=1.54, P＞0.05). There was no change in the mean blood leadlevel of the normal control group after the experiment (t=0.38, P＞0.05). On the 20thday, the mean lead level of the lead-model group were higher than those of the rest 7groups(P＜0.01), the mean lead level of the nutrient groups,EDTA group were higherthan that of the normal control group(P＜0.05), the mean lead level of the three jointnutrient groups were lower than that of the calcium group(P＜0.05), the three jointnutrient groups were lower than that of the selenium group(P＜0.05), the mean bloodlead levels of the calcium group and selenium group were higher than that of EDTAgroup (P＜0.05).3. On the 20th day, the mean lead levels of the lead-model group were higherthan those of the rest 7 groups(P＜0.01), the mean lead levels brain,liver and kidneysof the 5 nutrient groups,EDTA group were higher than that of the normal controlgroup(P＜0.05), the mean lead level of brain and liver of the three joint nutrient groupswere lower than that of the calcium group(P＜0.05),the brain and kidneys of threejoint nutrient groups were lower than that of the selenium group(P＜0.05), the mean blood lead levels of brain,liver and kidneys of the calcium group and seleniumgroup were higher than that of EDTA group (P＜0.05).4. On the 20th day, the mean lead levels of spleen,lungs and bones of thelead-model group were higher than those of the rest 7 groups(P＜0.01), the mean leadlevels of spleen,lungs and bones of the 5 nutrient groups,EDTA group were higherthat of the normal control group(P＜0.05), the mean lead level of lungs and bones ofthe three joint nutrient groups were lower than that of the calcium group(P＜0.05),themean lead levels of spleen and bones of three joint nutrient groups were lower thanthat of the selenium group(P＜0.05), the mean blood lead levels of spleen,bones andlungs of the calcium group and selenium group were higher than that of EDTAgroup (P＜0.05).5. On the 20th day, the mean NO contents and activity of NOS and iNOS ofbrains of the lead-model group were lower than those of the rest 7 groups(P＜0.01),the mean NO contents and activity of NOS and iNOS of brains of the 5 nutrientgroups, EDTA group were lower than that of the normal control group(P＜0.05), themean NO contents of brains of the three joint nutrient groups were higher thanthat of the calcium group(P＜0.05),the mean NO contents of brains of three jointnutrient groups were higher than that of the selenium group(P＜0.05), the mean NOcontents of brains of the calcium group and selenium group were lower than that ofEDTA group (P＜0.05).6. On the 20th day, the mean labyrinth-escaping time of the lead-model groupwere longer than those of the rest 7 groups(P＜0.01), the mean labyrinth-escaping timeof the calcium group and selenium group were longer than that of the normalcontrol group(P＜0.05), the mean labyrinth-escaping times of the three joint nutrientgroups were shorter than that of the calcium group(P＜0.05),the meanlabyrinth-escaping time of three joint nutrient groups were shorter than that of theselenium group(P＜0.05), the mean labyrinth-escaping times of the calcium group andselenium group were longer than that of EDTA group (P＜0.05).Conclusions 1.A certain dose of calcium or selenium(the dose in this experiment) can helpexcrete lead in rats.2.The joint use of calcium or selenium can promote the weight and excretion oflead of the lead-model rats and the contents of NO and the activity of NOS and iNOSof brain and shorten the labyrinth-escaping time more effectively than the singlenutrient like calcium or selenium does.