| Purpuses: By establishing a model of lactation overnutrition,the effects of overnutrition during lactation on glucose and lipid metabolism in rats and possible mechanisms of insulin resistance were explored.Method: To establish the model of lactation overnutrition,the three-day-old young rats were decapitated and randomly divided into two groups,3 in the small group(SL)and 10 in the standard group(NL),respectively as overnutrition group and control group.Mother rats are fed ordinary feed.Rats were monitored for their body weight during feeding.Fasting blood glucose was measured at 3 weeks and 9 weeks of age,respectively.The rats were sacrificed,and blood was taken from the eyelids.Liver and visceral adipose tissue were collected and the corresponding index was calculated.ELISA was used to detect serum lipids such as triglyceride(TG),cholesterol(TC),high-density lipoprotein(HDL)total free fatty acid(NEFA),and leptin(LEP)in rat serum.ELISA was used to detect serum glucose such as(INS),glucose transporter 4(GLUT4),insulin-like growth factor(IGF-1)and other glucose metabolism indicators and calculate the insulin sensitivity index(ISI),insulin resistance index(HOMA-IR),pancreatic ?-cell function evaluation index.The expression of peroxisome proliferator-activated receptor ?(PPAR?)and peroxisome proliferator-activated receptor ?(PPAR?)mRNA and protein were detected by real-time quantitative PCR and Western Blot.Microarray technology was used to detect microRNA(miRNA)profiles.The expression of miRNAs was detected by real-time quantitative PCR,and miRNAs that might regulate PPARs were screened.Results: 1.Compared with the NL group,the body weight of SL rats increased by 23.8% and 17.7% at 3 weeks and 9 weeks,respectively.Compared with the NL group,epididymal fat and perirenal fat content in the SL group were increased at the age of three weeks(P<0.05);epididymal/body weight,and perirenal/body weight index were increased.There was a statistically significant difference between the groups(P<0.05).At the age of nine weeks,the epididymal fat content,perirenal fat content,and epididymis/body weight index were all increased in the SL group.The difference was statistically significant(P<0.05);the perirenal circumference/body weight index increased,but between the two groups the difference was not statistically significant(P>0.05).At the age of three weeks,the visceral fat index of the SL group was higher than that of the NL group,and it was statistically significant,indicating that the model of the lactation overnutrition model was successful.2.Results of serum lipid metabolism in rats: Compared with NL group,the contents of TG and TC in SL group were increased at the age of three weeks,and the difference between the two groups was statistically significant(P<0.05);NEFA,HDL content decreased,but the difference between the two groups was not statistically significant(P> 0.05);LEP content increased,but the difference between the two groups was not statistically significant(P> 0.05).At the age of nine weeks,the contents of TG,TC and NEFA in the SL group were increased,and the difference between the two groups was statistically significant(P<0.05);the HDL content was decreased,but there was no significant difference between the two groups(P> 0.05);LEP content decreased,the difference between the two groups was statistically significant(P <0.05).3.Results of serum glucose metabolism in rats: Compared with NL group,the fasting blood glucose level in SL group was increased at the age of three weeks,and the difference between the two groups was statistically significant(P<0.05);IGF-1 The content increased,the difference between the two groups was statistically significant(P <0.05);INS content increased,but the difference between the two groups was not statistically significant(P> 0.05);GLUT4 content decreased,but the difference between the two groups There was no statistical significance(P>0.05).At the age of nine weeks,fasting blood glucose and INS content increased in the SL group,and the difference between the two groups was statistically significant(P<0.05);GLUT4 and IGF-1 levels decreased,and there was a statistically significant difference between the two groups(P<0.05).4.Rat insulin resistance evaluation index results: Compared with NL group,at the age of three weeks,the ISI and HOMA-IR of SL group increased,but there was no significant difference between the two groups(P > 0.05);HOMA-? The index decreased,and the difference between the two groups was statistically significant(P<0.05).At 9 weeks of age,the ISI of the SL group decreased,and the difference between the two groups was statistically significant(P < 0.05).The HOMA-IR was elevated and the difference between the two groups was statistically significant(P <0.05).High,but the difference between the two groups was not statistically significant(P>0.05).5.RT-PCR results showed that compared with the NL group,the expression of the liver tissue PPAR? mRNA and adipose tissue PPAR? mRNA in the SL group was decreased at the age of three weeks,but there was no significant difference between the two groups(P>0.05).At the age of nine weeks,the mRNA expression of PPAR? mRNA and adipose tissue PPAR? increased in the SL group,and the difference between the two groups was statistically significant(P<0.05).Western Blot results showed that compared with NL group,the expression of PPAR? protein in liver tissue and the expression of PPAR? protein in liver tissue of SL group at the age of three weeks decreased at the age of three weeks,and there was a statistically significant difference between the two groups(P <0.05).According to the results of microarray expression analysis of microarrays,miRNAs that may regulate PPARs were screened: miRNA221-3P and miRNA192-3P.Compared with NL group,RT-PCR results showed that the expression of miRNA221-3P increased in three-week-old SL group.The difference between the two groups was statistically significant(P<0.05);the expression of miRNA192-3P was decreased,but there was no statistical difference between the two groups(P>0.05).At the age of nine weeks,the expression of miRNA221-3P in SL group was increased,and the difference between the two groups was statistically significant(P<0.05).The expression of miRNA192-3P was decreased and the difference between the two groups was statistically significant(P<0.05).Conclusions:This study demonstrates that early postnatal overnutrition may have along-term effect on body weight and serum fatty acids,leading to changes in the body's glucose and lipid metabolism,making the rat insulin signaling pathway impaired and increasing the risk of IR.Through the detection of PPAR? and PPAR?,and the study on the expression of miRNA221-3p and miRNA192-3p,the mechanism of miRNA regulation on PPAR? and PPAR? was preliminarily explored. |
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