Adipose Y5R mRNA is higher in obese than non-obese humans and is correlated with obesity parameters

Neuropeptide Y is mainly expressed in the central nervous system to regulate food intake via its receptors, Y receptors, and in various peripheral tissues including adipose tissue. The objectives of this study were to compare Y5R mRNA and adipocyte parameters consisting of area, width, height, and perimeter either between obese and non-obese subjects or between subcutaneous and visceral fat as well as to compare between NPY, Y1R, Y2R, and Y5R mRNA expressions in subcutaneous and visceral adipose tissues. In subcutaneous and visceral adipose tissues, Y5R was greater in obese than in non-obese humans (both P 0.05). Y1R mRNA expression was highest followed by Y5R, Y2R, and NPY mRNA expressions, respectively, in subcutaneous and visceral adipose tissues. Visceral Y5R mRNA had positive correlations with body weight, body mass index, waist circumference, hip circumference (R asymptotic to 0.4), and visceral Y1R mRNA (R = 0.773), but had a negative correlation with the quantitative insulin sensitivity check index (R=0.421) (all P < 0.05). Subcutaneous and visceral adipocyte parameters were positively correlated with body weight, waist circumference, hip circumference, and waist-to-hip ratio, with greater values of correlation coefficient shown in visceral (R asymptotic to 0.5-0.8) than in subcutaneous adipocytes (R asymptotic to 0.4-0.6, all P < 0.05). The parameters of visceral adipocytes had positive correlations with serum NPY levels (R asymptotic to 0.4, all P 0.05). Y5R mRNA in visceral adipose tissue is related to increased obesity and reduced insulin sensitivity. The dominant Y receptors in subcutaneous and visceral adipose tissue might be the Y1 R and Y5R. Visceral adipocytes show higher correlations with obesity parameters than subcutaneous adipocytes, suggestive of an increased risk of metabolic syndrome in visceral obesity. Y1 R and Y5R in visceral adipose tissue might be targets of drug development in prevention or treatment of adiposity.