The expression of leptin receptor (OB-R) is downregulated by leptin in some cell lines.
This study investigated the expressions of leptin receptors at central nerve system
and peripheral site in a dietary model of obesity. Rats in the 8 week high-diet and
control group were classified based on body weight gain into obese and control groups.
Serum leptin and insulin concentrations were measured and gene expressions of short
form of leptin receptor (OB-Ra) and long form (OB-Rb) in hypothalamus and liver were
detected by RT-PCR. The levels of serum leptin in obese rats were increased compared
with control rats (p<0.05). The levels of OB-Ra and OB-Rb gene expressions in both
hypothalamus and liver in obese rats were reduced significantly (p<0.01). Serum leptin
concentrations of obese rats had a significant negative relationship with both of
OB-Ra or OB-Rb gene expression levels in hypothalamus and liver (p<0.01). On the other
hand, serum insulin levels had no relationship with OB-Ra or OB-Rb gene expression
levels in neither liver nor hypothalamus. Rats with diet-induced obesity have hyperleptinemia
and reduced expressions of leptin receptors in hypothalamus and liver. The results
suggest that a leptin downregulated OB-R expression is one of leptin resistant mechanisms
for maintaining obesity.
Leptin resistance - high-fat diet - rat - insulin
