Effect Of Drinking Strontium On Survival Period Of Daphnia And Antioxidant Mechanism In Mice

ObjectiveMinerals in drinking water is associated with human life.To understand mineral species,quantity and proportion in the drinking water for the human life cycle.To observe the effect of strontium in water on the survival period of Daphnia and study of the influence mechanism.To further clarify the regulate of mineral in drinking water on the survival of Daphnia.To provide scientific theoretical basis for human health and longevity.Methods1.By observing the survival period of Daphnia in five kinds of drinking water（pure water,tap water,hydrogen-rich water,filtered water,mineral water）,and measuring the water quality index of five kinds of drinking water and the content of common mineral elements in water,strontium,one of the mineral elements which has an effect on the survival period of Daphnia,was found.2.The effects of different concentrations of strontium on survival time were further observed in Daphnia pulex to verify the findings in the first part and explore the relevant mechanism from the perspective of antioxidant.The survival of one day old Daphnia pulex was observed in strontium concentration groups.The body length,heart rate of Daphnia pulex,the protein content,total antioxidant capacity（T-AOC）,the activity of peroxidase（POD）,catalase（CAT）,glutathione peroxidase（GSH-Px）,superoxide dismutase（SOD）,the content of malondialdehyde（MDA）and hydrogen peroxide（H₂O₂）at 7,14 and 21 days of age were recorded.3.The effect of drinking strontium on the antioxidant system in mice was investigated to further verify and study the possible mechanism of strontium on the survival period of Daphnia.Eighty 3-week-old clean-grade ICR mice were randomly assigned to the pure water group and three strontium concentration groups（0.5mg/L,2.5mg/L and 5.0mg/L）according to the national safe limit standard of natural mineral water.The strontium solution was prepared with pure water.Twenty mice in each group,half male and half female,were fed with the corresponding water as the only water source for 60 days.The daily water intake and body weight were recorded.After the experiment period,serum of mice were taken to determine the total antioxidant capacity（T-AOC）,hydroxyl radical inhibition rate,catalase（CAT）activity,superoxide dismutase（SOD）activity and malondialdehyde（MAD）content.Total antioxidant capacity（T-AOC）,hydroxyl radical inhibition rate,peroxidase（POD）activity,catalase（CAT）activity,glutathione peroxidase（GSH-Px）activity,superoxide dismutase（SOD）activity,malondialdehyde（MAD）content and hydrogen peroxide（H₂O₂）content were determined in liver,heart and kidney tissues.The RNA expression levels of catalase（CAT）,glutathione peroxidase 1（GSH-Px1）and manganese superoxide dismutase（Mn-SOD）genes in heart,liver and kidney tissues were determined by RT-PCR.The contents of nicotinamide phosphoribose transferase（NAMPT）and nicotinamide mononucleotide adenosine transferase（NMNAT1）in heart,liver and kidney tissues were determined by Elisa.Western blot was used to determine the levels of apoptosis regulatory proteins Bcl-2,Bax,Caspase-3 and Cleaved Caspase-3 in liver tissues.Results1.（1）The survival period of Daphnia pulex in the mineral water group was the longest among the five drinking water groups,including pure water,hydrogen-rich water,filtered water,tap water and mineral water.（2）The results of water quality analysis showed that the content of strontium in mineral water was much higher than the other four kinds of drinking water,suggesting that strontium might prolong the survival period of Daphnia pulex.（3）The concentration of 0.1mg/L,0.2mg/L and0.4mg/L strontium in water significantly prolonged the survival period of Daphnia japonica（P<0.05）,which confirmed that strontium in water can prolong the survival period of Daphnia pulex.2.At the age of 7 days of daphnia after intervention,the T-AOC in 0.1,0.2,0.4 and1.0mg/L strontium concentration group was significantly higher than that in PWC group（P<0.05）,the SOD enzyme activity in 0.4mg/L was significantly higher than that in PWC group（P<0.05）.POD activity in 0.2mg/L and 2.0mg/L groups was significantly higher than that in PWC（P<0.05）,POD activity in 0.4mg/L strontium concentration group was significantly lower than that in PWC group（P<0.05）.The MDA content in0.1mg/L,0.4mg/L,0.8mg/L,1.0mg/L and 2.0mg/L strontium concentration groups was significantly lower than that in PWC group（P<0.05）.At 14 days of age,the T-AOC in0.1mg/L,0.2mg/L and 0.4mg/L groups was significantly higher than that in PWC group（P<0.05）,and the SOD activity in 0.1mg/L-0.8mg/L strontium concentration groups was significantly higher than that in PWC group（P<0.05）.MDA content in strontium-containing groups was significantly lower than that in PWC group（P<0.05）.At 21 days of age,the T-AOC in 0.2mg/L,0.4mg/L and 0.8mg/L strontium concentration groups was significantly higher than that in PWC group（P<0.05）,and the SOD activity in 0.1mg/L,0.2mg/L and 0.8mg/L strontium concentration groups was significantly higher than that in PWC group（P<0.05）.The POD activity in 0.4mg/L and 2.0mg/L strontium concentration groups was significantly higher than that in PWC group（P<0.05）,MDA content in each strontium concentration group was significantly lower than that in PWC group（P<0.05）.In addition,the activities of CAT and GSH-Px in Daphna at 7,14 and 21 days of age were significantly enhanced by 0.1mg/L-0.8mg/L strontium concentration compared with those in PWC group（P<0.05）.3.The serum T-AOC in 2.5mg/L strontium concentration group was higher than that in PWC group（P<0.05）.（2）There were no differences in T-AOC,hydroxyl free radical inhibition rate and POD enzyme activity in heart,liver and kidney,SOD enzyme activity,GSH-Px enzyme activity in heart and kidney,CAT enzyme activity in heart and liver of mice among strontium concentration groups（P>0.05）.The activity of SOD in heart and liver of mice in 0.5,2.5 and 5.0mg/L strontium concentration groups were significantly higher than those in PWC group（P<0.05）.The CAT enzyme activity in kidney of mice in 2.5mg/L and 5.0mg/L strontium concentration groups was significantly higher than that in PWC group（P<0.05）.（3）The m RNA expression levels of CAT,Mn-SOD and GSH-Px1 in heart,kidney and liver of mice in 0.5mg/L strontium concentration group were not significantly different from those in PWC group（P>0.05）.2.5mg/L strontium concentration up-regulated the m RNA expression of Mn-SOD and GSH-Px1 gene in heart,and down-regulated the m RNA expression of GSH-Px1 gene in kidney（P<0.05）.5.0mg/L strontium concentration decreased the m RNA expression of Mn-SOD gene in heart and GSH-Px gene in kidney of mice（P<0.05）.（4）Compared with PWC group,the contents of NMNAT1 in heart,NAMPT and NMNAT1 in kidney of mice in 0.5mg/L strontium concentration group were significantly increased（P<0.05）;The contents of NMNAT1 in heart,NAMPT and NMNAT1 in liver of mice in 2.5mg/L strontium concentration group were significantly increased（P<0.05）;The contents of NAMPT and NMNAT1 in heart and liver and NMNAT1 in kidney of mice in 5.0mg/L strontium concentration group were significantly increased（P<0.05）.（5）In liver of mice,compared with PWC group:The protein expression levels of Bax and Cleaved caspase-3 in 2.5mg/L and 5.0mg/L strontium concentration groups were down-regulated（P<0.05）,and the protein expression levels of Bcl-2 in 0.5mg/L,2.5mg/L and 5.0mg/L strontium concentration groups were up-regulated（P<0.05）.The expression of Caspase protein in 0.5mg/L,2.5mg/L and 5.0mg/L strontium concentration groups was significantly down-regulated（P<0.05）.Conclusion1.0.1mg/L,0.2mg/L and 0.4mg/L strontium in water could prolong the survival period of Daphnia pulex,and 0.4mg/L strontium concentration group had the longest survival period.2.Strontium concentration of 0.1mg/L-0.8mg/L in water can significantly enhance the activities of CAT,GSH-Px of Daphnia at 7,14 and 21 days of age,and regulate the activity of SOD enzyme in different degrees,thus enhancing the antioxidant capacity,and thus delaying aging and prolonging life of Daphnia.3.Drinking strontium can enhance the activities of SOD enzyme in heart,CAT enzyme in kidney,SOD and GSH-Px enzyme in liver of mice.0.5mg/L drinking strontium can increase the contents of NAMPT and NMNAT1 in kidney at the same time,2.5mg/L drinking strontium can increase the contents of NAMPT and NMNAT1in liver at the same time,5.0mg/L drinking strontium can increase the contents of NAMPT and NMNAT1 in heart at the same time,which may increase the synthesis of NDA⁺in corresponding organs.Thus,the antioxidant capacity in mice is increased,which may reduce damage to cells caused by ROS accumulation.The Bcl-2/Bax ratio was kept high,and the activation of caspase-3 was reduced,thus the probability of cell apoptosis was reduced and the cell life was prolonged.4.These results suggest that strontium may be a longevity element.It may delay the occurrence of cell apoptosis by enhancing the antioxidant level in Daphnia,and then prolonging the survival period of Daphnia daphnia.