In Vivo Autophosphorylation Of Erythrocyte Insulin Receptors Of Polycystic Ovary Syndrome

Objective: To investigate tyrosine autophosphorylation of the insulin receptor in vivo in subjects with polycystic ovary syndrome(PCOS). Method: Case-control study. Sixteen PCOS and eight age- and body mass index matched control subjects were included in the study .Women with PCOS were classified as HI (n=8)or non-HI(n=8) on the basis of fasting insulin levels. (1) Serum levels of gonadotropins and ovarian steroids were determined. Oral glucose tolerance test(OGTT) and insulin releasing test were performed and insulin resistance index(HOMA-IR) was calculated. (2) Blood sample were obtained at five time-points during OGTT(Fasting and 30min, 60min, 120min ,180min after intaking 75g glucose orally ). Erythrocytes were isolated. Autophosphorylation insulin receptor (APIR) and total insulin receptor(TIR) content were analysed by enzymatic immunoassay . (3) The in vivo autophosphorylation degree of insulin receptors under different insulin concentrations was expressed as APIR/TIR ratios .Result: (1) HOMA-IR and LH/FSH were positively correlated with serum T level in HI-PCOS patients(r=0.708 P<0.05 and r=0.721 P<0.05 respectively); LH/FSH was positively correlated with serum T level in non-HI-PCOS patients(r=0.831, P<0.05), HOMA-IR was not correlated with serum T level in non-HI-PCOS patients; Both HOMA-IR and LH/FSH were not correlated with serum T level in either HI-PCOS or non-HI-PCOS patients. (2) No difference was found in erythrocyte TIR among HI-PCOS ,non-HI-PCOS and controls. (3) Mean APIR/TIR ratios in HI-PCOS patients were lower than that in non-HI-PCOS patients and controls at 60 minute after OGTT (P<0.05), whereas mean APIR/TIR ratios in non-HI-PCOS patients did not differ from controls significantly.Conclusion: HI-PCOS patients' autophosphorylation of the insulin receptor in vivo decreased and might be a mechanism for IR in PCOS.