Non-alcoholic fatty liver disease (
NAFLD) is considered to be associated with
metabolic syndrome; however, a number of
NAFLD patients are not obese. To explore any differences in lipid metabolism between obese and non-obese patients, we determined the expression of
fatty acid metabolism-related genes. Expression levels of target genes were quantified by real-time PCR using liver biopsy samples from
NAFLD patients and normal controls. Serum
adipocytokine levels were also determined. The expression of genes related to
fatty acid synthesis and uptake was generally up-regulated in
NAFLD patients; however, no significant difference was seen between obese and non-obese groups. Most of the genes tested related to
fatty acid and
reactive oxygen species (ROS) elimination, were overexpressed in
NAFLD and the levels were significantly higher in non-obese patients. As an exception,
peroxisome proliferator-activated receptor alpha expression was suppressed in
NAFLD and the levels were lower in the obese group.
Triglyceride synthesis-related genes were up-regulated and lipolytic
enzymes were decreased in
NAFLD, but there was no significant difference between the obese and non-obese groups. In
NAFLD, increased de novo synthesis and uptake of
fatty acids led to further hepatocyte accumulation of
fatty acids. The up-regulation of
fatty acid oxidation and the
antioxidant pathway and the suppression of lipolysis seemed to be involved in this process. Expression of genes related to
fatty acid oxidation and ROS elimination were higher in the non-obese group than in the obese group, which contributes to the trend of more severe liver injury,
insulin resistance and steatosis in obese patients.