Expressions of neuropeptide Y and Y1 receptor in subcutaneous and visceral fat tissues in normal weight and obese humans and their correlations with clinical parameters and peripheral metabolic factors.

Recently, neuropeptide Y (NPY) and Y1 receptor (Y1R) were found to be expressed and synthesized in adipose tissue. This study aimed to compare NPY and Y1R mRNA expressions in subcutaneous and visceral fat tissues as well as serum NPY in normal weight and obese humans and their correlations with clinical parameters and peripheral metabolic factors. We demonstrated that NPY mRNA expression was higher in obese than in normal weight humans (p<0.05) in both subcutaneous and visceral adipose tissues and was significantly greater in visceral when compared with subcutaneous fat in overall (p<0.01), obese (p<0.05) and normal weight humans (p<0.05). Y1R mRNA expression was higher in obese than normal weight subjects in visceral (p<0.01) but not in subcutaneous adipose tissue and was statistically greater in subcutaneous when compared to visceral adipose tissue in obese (p<0.05) and overall subjects (p<0.05). Serum NPY was higher in obese than normal weight groups (p<0.05). Obese subjects showed significantly greater levels of systolic blood pressure (SBP) (p<0.01), diastolic blood pressure (DBP) (p<0.05), plasma insulin (p<0.05), and HOMA-IR (p<0.05) when compared with normal weight subjects. Additionally, Y1R mRNA expression in visceral adipose tissue was positively correlated with body weight (R=0.586), BMI (R=0.611), waist (R=0.474) and hip (R=0.483) circumferences, insulin levels (R=0.539), and HOMA-IR (R=0.480). As the result, Y1R expression in visceral adipose tissue might be an indicator of increased risk of metabolic syndrome. Further studies about blocking specific Y1R may propose strategies for risk reduction in metabolic syndrome and prevention or treatment of obesity.