Karastergiou, Kalypso, Bredella, Miriam A., Lee, Mi-Jeong, Smith, Steven R., Fried, Susan K., Miller, Karen K.
funding text
NIH P30DK46200, R24DK087669, R01 HL077674, K24 HL092902, and K23 RR23090.
abstract
Objective: Growth hormone (GH) administration reduces abdominal, but not lower body, fat mass. To gain insight into the underlying mechanisms, this study examined the expression of the GH receptor (GHR) and some of its targets in abdominal and gluteal adipose tissue. Methods: GHR and GH targets in the lipolytic pathway were assessed (quantitative PCR/Western blotting) in adipose aspirates from premenopausal women [n = 15, age 26.9 +/- 6.1 years, body mass index (BMI) 28.0 +/- 6.8 kg/m(2)] and men (n=28, age 29.2 +/- 7.0 years, BMI 26.9 +/- 3.7 kg/m(2)). Results: GHR mRNA expression was lower in the gluteal depot when compared with the abdominal depot (P=0.01). Abdominal GHR correlated negatively with age and BMI, whereas gluteal GHR was associated with lower waist-to-hip ratio (WHR), that is, pear shape. In both sites, GHR mRNA correlated strongly with genes important for the regulation of lipolysis: adipose tissue triglyceride lipase (ATGL), hormone-sensitive lipase, perilipin, and CIDEA (all P<0.001), independently of BMI, WHR, age, and sex. GHR protein was lower in the gluteal fat when compared with the abdominal fat (P=0.03) and correlated with ATGL protein in the gluteal depot (P<0.001). Conclusions: GHR levels correlate with levels of lipases and lipid droplet-associated proteins crucial for lipolysis. Thus, higher GHR expression in the abdominal depot when compared with the gluteal depot may underlie the in vivo effect of GH to specifically reduce abdominal adipose tissue mass.