Correlations between the expression of the insulin sensitizing hormones, adiponectin, visfatin, and omentin, and the appetite regulatory hormone, neuropeptide Y and its receptors in subcutaneous and visceral adipose tissues

Adiponectin, visfatin, and omentin are adipokines involved in insulin sensitivity. Neuropeptide Y (NPY) and its receptors, Y1R, Y2R, and Y5R, are involved in appetite regulation. Here we examined the correlations between these two hormones groups in subcutaneous and visceral adipose tissues. We demonstrated that in subcutaneous adipose tissue, the adiponectin, visfatin and omentin expression positively correlated with that of subcutaneous NPY. Subcutaneous adiponectin expression positively correlated with subcutaneous Y1R and Y5R. Subcutaneous visfatin expression positively correlated with subcutaneous Y1R, Y2R, and Y5R. Subcutaneous omentin expression positively correlated with subcutaneous Y5R. In visceral adipose tissue, adiponectin, visfatin and omentin expression positively correlated with visceral NPY. Visceral visfatin expression positively correlated with visceral Y1R, Y2R and Y5R. There was no correlation between the subcutaneous and visceral expression of these adipokines and receptors. BMI correlated better with visceral adipocyte characteristics including width, height, perimeter, and area than with those of subcutaneous adipocyte. Visceral, but not subcutaneous, adipocyte parameters positively correlated with insulin and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), but negatively associated with Quantitative Insulin Sensitivity Check Index (QUICKI). These results suggest that adiponectin, omentin, and visfatin expression correlated with NPY expression in either type of adipose tissue, with no evidence of cross-linking between adipose tissue depots, suggesting that there might be (a) different regulation mechanism(s) between subcutaneous and visceral adipose tissues with regard to expressions of these two hormone groups. Further studies are required to identify factors that regulate the linkage between these hormones in each adipose tissue type.