Adiponectin is an adipocyte-derived
hormone that can improve insulin sensitivity. Its functions
in regulating glucose utilization and fatty acid
metabolism in mammals are mediated by 2 subtypes
of adiponectin receptors (AdipoR1 and AdipoR2). This
study was conducted to determine the effect of fasting
on the expression of adiponectin and its receptors.
The expression of adiponectin was not affected in s.c.
adipose tissue, but adiponectin expression increased in
visceral adipose tissue after fasting. In contrast, expression
of both AdipoR mRNA was increased in the liver
and s.c. adipose tissue of 24-h-fasted pigs compared
with fed pigs, but the mRNA in muscle and visceral
adipose tissue was not affected by fasting. A third putative
adiponectin receptor, T-cadherin, was cloned and
the mRNA expression was determined. T-Cadherin has
been recognized to act as a vascular adiponectin receptor
in vascular endothelial and smooth muscle cells. Our
data showed that the expression of T-cadherin was decreased
in the muscle of fasted pigs, suggesting that the
expression of T-cadherin can be regulated by feeding
status. In summary, in young pigs, adiponectin mRNA
was up-regulated by fasting in visceral, but not s.c.,
adipose tissue, whereas AdipoR1 and AdipoR2 mRNA
were increased in s.c., but not visceral, adipose tissue.
The adiponectin receptor, T-cadherin, was expressed in
s.c. and visceral adipose tissue and in muscle, but only
muscle mRNA expression was decreased by fasting.