Correlation Between Serum Asprosin And Insulin Levels

Objective This study analyzed the relationship between serum asprosin and insulin by measuring serum asprosin levels at different insulin levels.Methods1.A cross-sectional study was used to recruit 131 subjects who underwent oral glucose tolerance test?OGTT?in Endocrinology Laboratory of the First Affiliated Hospital of University of South China from August 2019 to March 2020,all subjects met the inclusion criteria and exclusion criteria.Hyperinsulinemia?HIns?was determined by fasting insulin?15 uIU/ml or 2h-PIns?80 uIU/ml.A total of 57 subjects were included in the HIns group and 74 subjects were included in the control group.Basic data of all subjects were collected,including age,sex,past medical history,family history and recent status of medication.Fasting plasma glucose,30min-PG,1h-PG,2h-PG,fasting insulin,30min-PIns,1h-PIns,2h-PIns,total cholesterol,triglyceride,low density lipoprotein cholesterol,high density lipoprotein cholesterol,glycosylated hemoglobin,creatinine,uric acid,alanine aminotransferase and alanine aminotransferase and other biochemical indices were determined for all subjects.Body mass index,area under the curve of insulin secretion and steady state model to evaluate insulin resistance index were calculated.Serum asprosin of fasting and time of insulin's peak level in OGTT were determined by double antibody sandwich enzyme-linked immunosorbent assay?ELISA?.2.36 male SD rats were randomly divided into the chow diet group?n=10?and the high-fat diet group?HFD,n=26?,they were fed on rat maintenance feed or high fat diet separately.Nine weeks later,those modeled obese SD rats?n=20?in the HFD group were randomly divided into HFD group?n=10?and the high-fat diet+metformin group?HFD+Met,n=10?,the dose of metformin hydrochloride tablets was 300 mg/?kg·d?.The chow diet group continued to be fed on rat maintenance feed,and the HFD group and HFD+Met group continued to be fed on high-fat diet.Three weeks later,five rats randomly selected of each group were dissected after twelve hours of fasting,and the intravenous blood,liver,abdominal subcutaneous adipose tissue?ASAT?and visceral adipose tissue?VAT?were obtained.VAT includes epididymal adipose tissue?EAT?,perirenal adipose tissue?PRAT?and mesenteric adipose tissue?MAT?.Intraperitoneal glucose tolerance test?IPGTT?was performed on the remaining 5 rats after fasting for 12 hours,intravenous blood,liver,ASAT and VAT were obtained 2 hours later.The serum insulin and asprosin levels of fasting and 2 hours after IPGTT were measured by ELISA method.Results1.Compared to the control group,fasting serum asprosin levels were significantly increased in HIns group?19.08±6.33 vs.25.46±7.88 ng/ml,P<0.001?.2.In all individuals,fasting serum asprosin was positively correlated with TG,FPG,HbA1c,FIns,AUC_insulinnsulin and HOMA-IR?P<0.01?.3.Multivariate logistic regression analysis demonstrated that fasting serum asprosin levels were independently associated with the occurrence of HIns.ROC curve analysis showed that the optimal cut-off value of fasting serum asprosin?sex and age adjusted?for predicting the prsence of HIns was 26.15 ng/ml?AUC=0.679[0.590,0.769],P<0.001?.4.OGTT results showed,compared to the fasting serum asprosin concentrations,serum asprosin concentrations of OGTT insulin peak time decreased significantly in the control group?23.56±9.52 vs.18.50±9.41 ng/ml,P<0.001?.Compared to the fasting serum asprosin concentrations,the decrease in serum asprosin levels of OGTT insulin peak time was attenuated in the HIns group,the difference was not statistically significant?28.28±10.68 vs.25.10±8.79 ng/ml,P>0.05?.5.Body weight,the weight of ASAT and VAT?including EAT,PRAT and MAT?of rats in HFD group were significantly higher than those in chow diet group after 12 weeks of feeding separately.After 3 weeks treatment of metformin,body weight,the weight of ASAT and VAT?including EAT,PRAT and MAT?of rats in HFD+Met group were significantly lower than those in HFD group,the differences were statistically significant?P<0.05?.6.Compared to fasting serum asprosin concentrations,asprosin concentrations of 2 hours after IPGTT decreased significantly in the chow diet group group?P<0.05?.whereas,compared to fasting serum asprosin concentrations,the decrease in serum asprosin concentrations of 2 hours after IPGTT was attenuated in the HFD group,the difference was not statistically significant?P>0.05?.After treatment of metformin in HFD+Met,asprosin concentrations of 2 hours after IPGTT decreased significantly comparing with fasting serum asprosin concentrations?P<0.05?.Conclusion1.Fasting serum asprosin concentrations are significantly increased in HIns patients,and the regulatory function are impaired after glucose stimulation.The results suggest that high levels of insulin may be associated with regulatory dysfunction of asprosin secretion.2.Serum insulin and asprosin concentrations are significantly increased in obesity SD rats induced by high fat diet,while metformin can reduce their serum insulin and asprosin concentrations significantly,and improved the regulatory function of asprosin secretion.