Objectives: This study investigated the effect of starvation on mRNA levels of hepatic acyl coenzyme A synthetase (ACS), carnitine palmitoyltransferase-I (CPT-I), and acetyl coenzyme A carboxylase (ACC) and on serum concentrations of leptin, insulin, and glucose in male Sprague-Dawley rats.
Methods: Rats were fed an AIN-76 diet for 5 wk and then assigned to a normal group (NG) and a starvation group (SG). The SG was starved for 48 h and the NG was fasted for 12 h before being killed. Serum and hepatic lipids and serum levels of leptin, insulin, and glucose were determined. Expressions of ACS, CPT-1, and ACC mRNA were assessed in liver.
Results: Serum concentrations of triacylglycerol and high-density lipoprotein cholesterol in the SG were lower than those in the NG. Serum concentrations of low-density lipoprotein cholesterol in the SG were significantly higher than in the NG. Hepatic concentrations of total lipid in the SG were significantly higher than those in the NG, and triacylglycerol concentrations in the SG were significantly lower than those in the NG. Serum concentrations of leptin and glucose in the SG were significantly lower than those in the NG. The ratio of abdominal fat to total body weight in the SG was lower than that in the NG. Hepatic ACS and CPT-I mRNA levels in the SG were significantly higher than those in the NG, but hepatic ACC mRNA levels were lower in the SG than in the NG.
Conclusions: We demonstrated that starvation increases hepatic levels of ACS and CPT-I and decreases transcription levels of ACC, implicating increases in fatty acid oxidation. This research demonstrates a coordinated regulation of ACS, CPT-I, and ACC mRNA levels and serves to enhance our understanding of the molecular mechanisms underlying fatty acid metabolism during starvation.