Effect And Its Mechanisms Of Paternal Cadmium Exposure On Hepatic Glucose And Lipid Metabolism In Offspring

Background:Early-life exposure to environmental makes more susceptible to offspring chronic diseases in later life.Previous studies found that maternal environmental cadmium exposure caused glucose and lipid metabolism disorders in offspring.However,the effect and its mechanism of paternal environmental cadmium exposure on glucose metabolism in offspring are still unclear.Objective:This study investigated the impacts and mechanisms of paternal cadmium exposure on hepatic glucose and lipid metabolism in offspring.Methods:In order to investigate the effects of different doses of paternal Cd exposure on hepatic glucose and lipid metabolism in offspring,C57BL/6N male mice at4-week-old were randomly divided into control group,low cadmium group and high cadmium group,and were respectively given 0,10 or 100 mg/L Cd Cl₂solution by drinking water.All male mice were bred until 15 weeks old and mated with unexposed female mice to obtain pregnant mice.Some pregnant mice were dissected on day 18 of pregnancy,and the fetal mice and fetal livers were collected.In the rest of the pregnant mice,natural delivery was allowed to take place until the postnatal day 1 for gender adjustment（3 males and 3 females each）,and were weaned at PND 28.In PND105,the glucose tolerance test was performed on male and female offspring to evaluate the glucose regulation ability,followed by the insulin tolerance test to evaluate the insulin sensitivity,and finally the energy metabolism was evaluated by indirect calorimetry.After all the tests were completed,the offspring mice were killed,and the livers and plasma were taken.The lipid metabolism level of the offspring mice was measured by lipomics;The expression level of mouse genome was detected by transcriptomics;The protein levels of related indicators of glucose and lipid metabolism in offspring mice were detected by Western blot;Real-time RT-PCR assay was used to detect the level of glucose and lipid metabolism-related m RNAs in offspring mice;The glycogen level of liver was detected by glycogen staining;The plasma insulin level was detected by enzyme-linked immunosorbent assay.Results:Daily growth and development evaluation and indirect calorimetry showed that paternal high cadmium exposure significantly decreased the body weight and increased the energy consumption in adult offspring mice,with no significant difference in food consumption.Meanwhile,we found that paternal high cadmium exposure resulted in decreased the liver weight in adult female offspring.The above results suggested that parental high cadmium exposure caused growth retardation and liver development impairment in offspring mice.Glucose metabolism-related experiments showed that paternal high cadmium exposure caused impaired glucose tolerance,insulin resistance and abnormal hepatic glycogen accumulation in adult female offspring,but not in males,suggesting that paternal high cadmium exposure caused hepatic glucose metabolism dysfunction in a sex-dependent manner.Lipidomic datas showed that parental high cadmium exposure increased hepatic multiple phospholipids content in adult female offspring,but not in males,suggesting that parental high cadmium exposure caused hepatic phospholipid accumulation in a sex-dependent manner.Further transcriptome analysis showed that the expression of insulin signaling and lipid transport-related m RNAs and proteins were significantly impaired in adult female offspring livers after paternal high cadmium exposure.Subsequently fetal livers and paternal sperm transcriptomics data were found that paternal high cadmium exposure increased multiple phospholipid components in the female fetal liver,and the three metabolites were also significantly increased in PC 38:2,PC-（O）-30:0,and PC-（P）-36:5,but not in male,were consistent with adult results.Finally,we crossed the differentially expressed m RNAs between paternal sperm and female fetal livers,and found that the overlapping DEm RNAs were enriched into phospholipid transport-related signaling pathways.Further RT-q PCR validation demonstrated that paternal high cadmium reduced the levels of Pipnb and Slc10a7 m RNAs,which are related to phospholipid transport in sperm and female fetal liver.Conclusion:Paternal high cadmium exposure causes phospholipid accumulation and insulin resistance in adult female offspring livers:may be the decreased expression of phospholipid transport-related m RNAs in fetal female livers and paternal sperm.