Skeletal Muscle Phosphatidylinositol 3-kinase Expression Relationship Study, And Gestational Diabetes Mellitus Insulin Resistance

Objective To investigate the relationship between the expression of Phosphatidylinositol 3-kinase(PI-3K) in skeletal muscle and insulin resistance from women with gestational diabetes mellitus(GDM).Methods The expression of PI-3K regulative subunit p85a mRNA and protein in skeletal muscle were determined by RT-PCR and western blot from patients with GDM (GDM group,n=30), normal pregnant women (normal pregnancy group, n=30) and nonpregnant women (control group, n=20). Fasting plasma glucose (FPG),fasting insulin (FINS) and growth hormone(GH) were measured by oxidized assay and immunoradioassay. Insulin resistant index (HOMA-IR) was calculated according FPG and FINS.Results 1. The levels of FPG, FINS , and HOMA-IR [(5.61±0.78) mmol/L,(15.12±5.31) mU/L, and 1.21±0.52] in GDM group were significantly higher than those in normal pregnancy group[(4.43±0.46) mmol/L,(10.56±3.07) mU/L, and 0.80±0.31; P<0.01]. The levels of GH in GDM(10.45±2.54ng/ml) and normal pregnancy group (10.20±3.17) were significantly higher than that in control group (2.25±1.42, P<0.001) . 2. The levels of P85amRNA(1.08±0.23) and protein(0.81±0.32) expression in GDM group were significantly higher than those in normal pregnancy group (0.88±0.29, 0.55±0.27; P<0.01) and control group(0.63±0.26, 0.28±0.20; P<0.01). 3. Expression of P85amRNA and protein was positively correlated with HOMA-IR (r=0.625,0.759; P<0.01) in GDM group. 4. The levels of GH was positively correlated with the expression of P85amRNA and protein in normal pregnancy group(r=0.382,0.369, p<0.05).Conclusion 1.Upregulative P85amRNA and high expression of P85a protein in skeletal muscle may be one of the molecular mechanisms leading to insulin resisitance in patients with GDM. 2. GH induced insulin resistance in pregnancy maybe caused by a mechanism involving the P85a overexpression.