Ghrelin in Gestational Diabetes: Serum Level and mRNA Expression in Fat and Placental Tissue

Objectives: We studied the effect of an oral glucose load on circulating ghrelin, as well as ghrelin and ghrelin receptor (GHS-R1a) mRNA expression in subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT) and placental tissue from pregnant women with gestational diabetes (GDM) and normal glucose tolerance (NGT). Methods: Plasma total ghrelin levels were measured in 58 patients with GDM and 61 women with NGT by radioimmunoassay. Ghrelin and GHS-R1a mRNA expression was studied in 16 subjects with GDM and 20 healthy pregnant women at term, using RT-PCR. Results: Basal ghrelin concentrations and the maximal decrease in ghrelin levels after glucose load did not differ in the women with GDM and NGT (399.1 [299.6-563.3] pg/ml vs. 400.9 [302.3 475.8] pg/ml and 127.6 [23.1-213.1] pg/ml vs. 101.7 [44.0-217.6] pg/ml, respectively). Ghrelin mRNA expression in placental tissue was significantly higher in the subjects with GDM than in the healthy pregnant women (0.06 [0.03-0.07] AU vs. 0.02 [0.015-0.03 AU], p = 0.02), whereas GHS-R1a mRNA expression in all three tissues studied did not differ between the two groups. Multiple regression analysis revealed that ghrelin mRNA expression in SAT was significantly predicted by serum insulin (beta = 0.62, p = 0.01), explaining 42 % of its variability. Conclusions: Ghrelin mRNA expression in placental tissue was higher in the GDM than in NGT subjects, whereas no association between circulating ghrelin and GDM was observed.