Study On Changes Of CTRP3,Placental INS/IGF-1 Signaling Pathway-Related Factors And GLUT-1 Expression And Relationship With Fetal Birth Weight In Pregnant Women With GDM

Background:Gestational Diabetes Mellitus（GDM）is a common disease of abnormal glucose metabolism during pregnancy.GLUT-1 is the most essential glucose transporter protein in placental tissues,and when the expression of GLUT-1is changed,it affects the transport of glucose from mother to fetus,which affects the fetal growth.However,the expression of GLUT-1 in placental tissues of pregnant women with GDM and its effect on fetal growth are not clear.Low levels of adiponectin（APN）in venous blood of GDM patients are not only associated with the development of GDM,but can also promote fetal overgrowth by decreasing the expression of peroxisome proliferator-activated receptors-α（PPAR-α）in placental tissue,reducing the inhibition of insulin（INS）/insulin-like growth factor-1（IGF-1）signaling pathway,and increasing the expression of GLUT-1.Complement C1q/tumor necrosis factor-related protein-3（CTRP3）,a novel adipokine with high homology to APN in structural composition and biochemical characteristics,was found to be low in GDM patients in early,second and third trimesters,and it is suggested that CTRP3 has a similar role to APN in the development of GDM.Whether CTRP3 in maternal blood,cord blood and placental tissue is associated with fetal growth in pregnant women with GDM,and whether maternal blood CTRP3 may be involved in the regulation of FBW PPAR-α-mediated regulation of the INS/IGF-1 signaling pathway have not been reported.Objective:1 To investigate the clinical and prenatal glycolipid metabolic characteristics of pregnant women with diet-treated GDM and their relationship with FBW.2 To reveal the changes of serum INS and IGF-1 and placental tissue INS/IGF-1 signaling pathway correlated factors and GLUT-1 expression in GDM pregnant women and their relationship with FBW,by measuring the contents of INS and IGF-1 in maternal blood and the protein expression levels of INS/IGF-1 signaling pathway-related factors IRS-1 and Akt and their phosphorylation products p-IRS-1 and p-Akt,and the expression levels of GLUT-1 m RNA and protein in placental tissue,3 By measuring the levels of CTRP3 in maternal blood and cord blood,as well as the levels of CTRP3 m RNA and protein expression,PPAR-αand its phosphorylation products in placental tissues,explored whether CTRP3might affect GLUT-1 expression through PPAR-α-mediated regulation of the INS/IGF-1 signaling pathway in placental tissues.Methods:Pregnant women with GDM who received dietary control alone and pregnant women with NGT who delivered during the same period in the obstetrics department of the Affiliated Hospital of Chengde Medical College were selected for the study from December 2021 to December 2022.A total of 30 cases in the GDM group and 56 cases in the NGT group were included according to the diagnostic criteria,inclusion criteria and exclusion criteria.General demographic characteristics,height and pre-pregnancy weight,prenatal weight,presence of comorbidities and complications during pregnancy,history of common chronic diseases,gestational age at delivery,mode of delivery and presence of delivery complications,sex,birth weight,growth and development of the newborn were collected through physical examination,questionnaires and recording of delivery information.Fasting venous blood before delivery,fetal umbilical vein blood after delivery and placental tissue were collected from pregnant women.ELISA was performed to detect CTRP3 in maternal fasting venous serum and umbilical vein serum and IGF-1 in pregnant women’s venous serum.q RT-PCR was performed to detect CTRP3 and GLUT-1 m RNA gene expression in placental tissues;Western blot was performed to detect PPAR-α,IRS-1,Akt protein and p-PPAR-α,p-IRS-1,p-Akt protein as well as CTRP3 and GLUT-1 protein expression in placental tissues.Serum CTRP3 and IGF-1 levels were expressed as mean±standard deviation（?x±s）or median（lower quartile,upper quartile）[M(P₂₅to P₇₅)],and two independent samples t-test or Wilcoxon rank sum test were used for comparison between groups;correlation between two variables was performed by Pearson or Spearman correlation analysis.All two-sided tests were used,and differences or correlations were considered statistically significant at P<0.05.Results:1 Maternal and neonatal clinical characteristics and their correlation with FBW:There were no statistically significant differences in gestational weight gain,fetal birth weight,gestational age at delivery and the proportion of macrosomic between the GDM and NGT groups（P>0.05）.Pre-pregnancy BMI（kg/m²）（23.32±0.46 vs 22.10±0.36）and neonatal sex composition（male/female:73.3%/26.7%vs 44.6%/55.4%）of pregnant women in the GDM and NGT groups,and the differences were statistically significant（P<0.05）.The correlation between gestational weight gain and FBW was positive in both the GDM（r=0.381,P=0.038）and NGT（r=0.289,P=0.031）groups;the correlation between maternal age,gestational age at delivery,and pre-pregnancy BMI and FBW were not statistically significant（P>0.05）.2 The prenatal glucose and lipid metabolism indexes of pregnant women and their correlation with FBW:the prenatal venous blood FINS（pmmol/L）[128.05（89.33,172.23）vs 96.90（72.04,118.35）],IGF-1（ng/L）[421.97±8.10 vs 366.41±8.93],FBG（mmol/L）[4.15（3.83,4.32）vs 3.97（3.64,4.13）]and HOMA-IR[3.41（2.32,4.70）vs 2.50（1.76,2.85）]levels of pregnant women in the GDM were higher than those in the NGT group,and the differences were statistically significant（P<0.05）;however,the differences in HOMA-βbetween the two groups were not statistically significant（P>0.05）.The differences in prenatal venous blood TC,TG,HDLc,LDLc,APOA1,APOB and LP（a）between the GDM and NGT groups were not statistically significant（P>0.05）.Except for the level of IGF-1 in venous blood of pregnant women in the GDM group,which was positively correlated with FBW（r=0.392,P=0.036）,the correlation between all other glycolipid metabolic indexes and FBW was not statistically significant（P>0.05）.3 Serum CTRP3 levels,CTRP3 protein and m RNA expression in placental tissues and their correlation with FBW:In the GDM and NGT groups,the prenatal venous serum CTRP3 levels[0.20±0.01 vs 0.24±0.01]and umbilical vein serum CTRP3 levels[0.35±0.02 vs 0.43±0.02]were both lower in the GDM group than in the NGT group,and all differences were statistically significant（P<0.05）.The correlations between maternal venous serum and umbilical vein serum CTRP3 levels and FBW were not statistically significant（P>0.05）.The differences in CTRP3 protein expression（0.83±0.08 vs 0.91±0.11）and CTRP3 m RNA expression[0.80（0.54,1.29）vs 0.93（0.66,1.42）]in placental tissues between the GDM and NGT groups were not statistically significant（P>0.05）;In the GDM group,the differences in CTRP3 protein and m RNA expression in placental tissues were not statistically significant in correlation with FBW（P>0.05）.4 Protein expression of INS/IGF-1 signaling pathway-related factors in placental tissues:the differences in protein expression of IRS-1（1.26±0.09vs 1.13±0.07）and Akt protein（0.82±0.04 vs 0.84±0.04）in placental tissue between the GDM and NGT groups were not statistically significant（P>0.05）;The expression of p-IRS-1 protein（2.66±0.21 vs 2.07±0.17）and p-Akt protein（1.54±0.09 vs 1.30±0.08）were higher in the GDM group than in the NGT group,and the differences were statistically significant（P<0.05）;PPAR-αprotein expression（1.11±0.04 vs 1.24±0.04）was lower in the GDM group than in the NGT group,and the difference was statistically significant（P<0.05）;The difference in p-PPAR-αprotein expression（0.53±0.07 vs0.54±0.07）was not statistically significant in the two groups（P>0.05）.5 GLUT-1 protein and m RNA expression in placental tissues and their correlation with FBW:The level of GLUT-1 protein expression in the placental tissue of pregnant women in the GDM group was higher than that in the NGT group（1.37±0.08 vs 1.15±0.05）,with statistically significant differences（P<0.05）.The difference in GLUT-1 m RNA expression[0.85（0.53,1.46）vs 0.89（0.74,1.43）]was not statistically significant in the GDM and NGT groups（P>0.05）.The correlation between GLUT-1 protein and m RNA expression and FBW in placental tissues of pregnant women in both groups was not statistically significant（P>0.05）.6 Association of serum CTRP3 with GLUT-1 and PPAR-αprotein expression:The correlation between maternal venous serum CTRP3 levels and the protein expression of GLUT-1 and PPAR-αin placental tissue was not statistically significant in the GDM group（P>0.05）.Conclusions:1 Pregnant women with GDM on dietary treatment had elevated pre-pregnancy BMI and abnormal prenatal glucose metabolism,but none correlated with FBW.2 Elevated IGF-1 levels in venous serum of pregnant women with GDM may increase GLUT-1 protein expression in placental tissue by upregulating the activity of the INS/IGF-1 signaling pathway in placental tissue,but GLUT-1 protein expression lacks correlation with FBW.3 CTRP3 levels in maternal venous serum and umbilical vein serum of pregnant women with GDM decreased compared with those in NGT group.But CTRP3 levels in maternal venous serum and umbilical vein serum and the expression levels of CTRP3 m RNA and protein in placental tissue of pregnant women with GDM did not correlate with FBW;CTRP3 in venous blood of pregnant women with GDM may not affect GLUT-1 expression through PPAR-α-mediated regulation of the INS/IGF-1 signaling pathway in placental tissue.