Increases in hepatic fructose-2,6-bisphosphate level and fructose-6-phosphate,2-kinase activity in rats with ventromedial lesions of the hypothalamus.

Abstract

To investigate altered fructose-2,6-bisphosphate (fructose-2,6-P2) metabolism, we measured fructose-2,6-P2 levels and fructose-6-phosphate,2-kinase (fructose-6-P,2-kinase) activities in various tissues, including liver, kidney, heart, and skeletal muscle, of ventromedial hypothalamus (VMH)-lesioned rats during feeding and starvation. The plasma insulin level was 6 times or more higher in these rats than in the controls. The fructose-2,6-P2 level in liver was much greater in VMH-lesioned rats than in the controls: 15.1 +/- 2.2 nmol/g tissue versus 7.7 +/- 0.7 in the fed state, 5.3 +/- 1.1 versus 1.6 +/- 0.4 in the starved state. In kidney, heart, and skeletal muscle, fructose-2,6-P2 levels were not different between the two animal groups. The activity of hepatic fructose-6-P,2-kinase remained high after 20 h of starvation in VMH-lesioned rats, whereas it was decreased markedly in the controls. The hepatic concentration of fructose-6-phosphate was also high in VMH-lesioned rats. Both fructose-6-P,2-kinase activity and fructose-6-phosphate concentration in the liver of starved VMH-lesioned rats were comparable to those of control rats in fed conditions. These results indicate that the alteration of fructose-2,6-P2 metabolism is characteristic of liver in VMH-lesioned rats, and that the increase in hepatic fructose-2,6-P2 may activate hepatic glycolysis not only during feeding but also during starvation, leading to the enhanced lipogenesis in these obese rats.

• Authors: Y Yamada, T Shimizu, N Hara, I Mineo, M Kawachi, H Kiyokawa, K Yamada, S Fujioka, Y Matsuzawa, N Kono
• Journal: Journal of biochemistry (J Biochem) Vol. 104 Issue 4 Pg. 576-9 (Oct 1988) ISSN: 0021-924X [Print] England
• PMID: 2853707 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Fructosediphosphates
• Fructosephosphates
• Hexosediphosphates
• Lipids
• fructose-6-phosphate
• fructose 2,6-diphosphate
• Phosphotransferases
• Phosphofructokinase-2

Topics

• Animals
• Fructosediphosphates (metabolism)
• Fructosephosphates (metabolism)
• Hexosediphosphates (metabolism)
• Hypothalamus, Middle (physiology)
• Lipids (biosynthesis)
• Liver (metabolism)
• Male
• Muscles (metabolism)
• Myocardium (metabolism)
• Obesity (metabolism)
• Phosphofructokinase-2
• Phosphotransferases (metabolism)
• Rats
• Rats, Inbred Strains