Modulation of apolipoprotein gene expression in fatty liver of obese rats: Enhanced APOA-IV, but no APOB expression by a high sucrose diet

OBJECTIVE: Hepatic lipoprotein production is important to the understanding of mechanisms involved in the development of fatty liver and hyperlipidemia. Previously, we have reported that hepatic fatty acid synthesis and apolipoproteinB transcription are increased in obese rats. Here, we describe the effects of a high sucrose diet on hepatic fatty acid synthesis and apolipoprotein gene expression in obese rats. DESIGN: Obese rats with ventromedial hypothalamic lesions were fed on a high sucrose diet (30.3% of cal) or lab chow for 11 weeks. RESULTS: Serum triglycerides and plasma immune-reactive insulin concentrations were further increased in the obese rats fed a high sucrose diet. The experimental diet increased the activity of hepatic acetyl-CoA carboxylase, the rate limiting enzyme for hepatic fatty acid synthesis, and triglycerides content, concurrent with an increase abundance of apolipoproteinA-IC mRNA in the obese rats. Despite further accumulation of hepatic triglycerides there was no further increase in hepatic apolipoproteinB mRNA abundance in the obese rats fed the high sucrose diet. CONCLUSION: These data suggest that the synthesis of hepatic fatty acids but not of apolipoproteinB is further increased in obese rats fed the high sucrose diet, and that apolipoproteinA-IV gene expression may be modulated in response to alterations in hepatic triglycerides flux.