| Objectives:Polycystic ovarian syndrome (PCOS) is universally recognised as the commonest endocrinopathy of women, it affects about 6% to 8% of reproductive-aged women worldwidely. Its basic features include chronic oligo and/or anovulation, polycystic ovaries, and clinical and/or biochemical signs of hyperandrogenism.PCOS has various of clinical manifestation,whose pathogenesy is not identified clearly yet. Meanwhile,it is accompanied by some abnormal metabolisms frequently,such as obesity and insulin resistance. Clinically, diagnosing a woman as having PCOS implies an increased risk for type 2 diabetes mellitus, dyslipidemia, hypertension, and possibly cardiovascular disease in the future. Apelin was identified firstly by a Japanese scientist as the endogenous ligand of the orphan G protein-coupled receptor APJ,and in 2005 it was confirmed as a novel cytokine.Apelin has been shown to be widely expressed in humans,it may have different biological activities including regulating insulin secretion. Many studies showed that the level of blood apelin was increased in obese cases with hyperinsulinism,so the researchers presumed that apelin might be involved in the pathogenesis of obese and insulin resistance.There were so many researches on the apelin level of cases with type 2 diabetes, howerver,nobody investigates the apelin level of PCOS,which are another important objects with insulin resistance.Thus, the aim of this study is to investigate①the levels of blood apelin in women with PCOS and the health control;②the correlation between level of blood apelin and fast insulin, homeostasis model assessment-insulin resistance (HOMA-IR) index and body weight index (BMI) et al in women with PCOS.Methods:69 patients with PCOS and 31 controls were selected and each group was divided into overweight/obese and non-obese subgroups according to body mass index(BMI)≥25 kg/m2 or<25 kg/m2. The level of fasting serum apelin was assayed by radioimmunoassay. Meanwhile, fasting plasma glucose(FPG), fasting insulin level(FINS),E2,FSH,LH,T levels were also measured. BMI and waist-to-hip ratio(WHR) were evaluated and insulin sensitivity was assessed by HOMA-IR.In addition, the difference of serum apelin levels and other indexes were compared between PCOS and controls as well as among each subgroups, The relationship between serum apelin levels and BMI, WHR, FINS,HOMA-IR were analyzed by statistical simply correlation and step regression analysis.Results:(1)PCOS and control group had same age construction. BMI,waist circle,T,LH and LH/FSH were higher in PCOS group than controls,whereas WHR was similar between these two groups and between overweight/obese subgroups.(2)FPG were similar between two groups and between each subgroups;FINS,HOMA-IR and serum apelin levels were significantly increased in PCOS compared with controls (45.12±55.59 vs 7.31±5.72mIU/l;10.19±12.63 vs 1.62±1.23;229.37±19.38 vs 218.58±15.95pg/ml,all P<0.01);in addition,both PCOS subgroups had higher FINS and HOMA-IR than correspoding control subgroups,but the difference of serum apelin levels only existed in BMI≥25 overweight/obese subgroups.(3) Fasting serum apelin levels correlated positively withBMI,waist circle,FINS and HOMA-IR(the value of r was respectively 0.705,0.558,0.435,0.429,P<0.001);there was no relation of apelin with age,WHR,T,LH,FSH,LH/FSH and FPG(P>0.05).(4)Multiple stepwise regression analysis showed that BMI was the independent factor related to the level of serum apelin.Conclusion:We assayed the apelin level in patients with PCOS and analyzed the correlation of apelin and obesity,insulin resistance.Our results showed that obese(especially abdominal obesity)and insulin resistance leaded to the higher apelin level of PCOS than controls,which was also associated with BMI,waist circle,FINS and HOMA-IR.More delicate and deeper researches should be wanted to determine the clear mechanism of how to regulate the apelin gene expression in different insulin-sentive tissues and to study the role of apelin playing in obese women and the pathogenesis of PCOS.
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