Abstract
Differences in fat cell size and function among adipose tissue depots are welt known
and may be important in the pathophysiology of the metabolic and cardiovascular complications
of obesity. Since the newly discovered adipocyte hormone leptin is thought to be a
central factor in the regulation of energy homeostasis, it may be interesting to know
if there are regional differences in leptin production. The aim of this study was
to compare the level of leptin expression in the omental and subcutaneous abdominal
adipose tissue from obese humans. Adipose tissue samples were collected from 25 severely
obese adults (mean BMI: 48.9 ± 9.7 kg/m2) undergoing vertical gastric banding. Semi-quantitative determination of leptin mRNA
by the RT-PCR technique showed significantly lower leptin expression in omental compared
to subcutaneous abdominal adipose tissue (leptin/Sp 1 ratio in omental vs. subcutaneous
fat: 1.53 ± 0.89 vs. 3.02 ± 1.58, p <0.01). Identical results were obtained when Northern
blotting was applied in a subgroup. Leptin expression increased with age in omental
adipose tissue (r = 0.42, p < 0.05), but not in subcutaneous tissue. No correlation
was found between BMI or waist/hip ratio (WHR) and leptin expression in omental or
subcutaneous adipose tissue. The regional difference in leptin expression was similar
in the patients with impaired glucose tolerance/type-2 diabetes and those with normal
glucose tolerance. In conclusion, the results of this study indicate that leptin expression
is lower in omental than subcutaneous adipose tissue, possibly due to differences
in fat cell size and/or sympathetic innervation.
Key words
Human Adipose Tissue - Leptin - Obesity - Regional Difference
