Effects of progesterone on some enzymes of fat and carbohydrate metabolism in rat liver

Abstract

The known effect of progesterone on carbohydrate metabolism prompted a study of some of the hepatic "lipogenic" and "gluconeogenic" enzymes in rats treated with progesterone. Several enzymes providing lipid precursors (phosphofructokinase, malic enzyme, glucose-6-phosphate dehydrogenase, and citrate cleavage enzyme) showed increased specific activity. These changes may represent insulin effects. Specific activity of phosphoenolpyruvate carboxykinase, usually associated with control of gluconeogenesis, was also increased. The latter is compatible with increased capability for glycogenesis, which is recognized as a progesterone effect.

PIP: The effects of progesterone on some of the hepatic enzymes associated with lipogenesis and gluconeogenesis in rats is presented. Progesterone was given, 1.25 mg, twice daily, for 14 days followed by 2.5 mg twice daily for 7 days. Animals were killed after 21 days of treatment. Enzymes studied included phosphofructokinase (PFK) malic enzyme (ME), glucose-6-phosphate dehydrogenase (G-6-PD), citrate cleavage enzyme (CCE), glycerol-3-phosphatee dehydrogenase (g-3-PD), fatty acid synthetase (FAS), pyruvate carboxylase (PC), phosphenolpyruvate carboxykinase (PEPCK), fructose-1,6-diphosphatase (FDPase), and lactate dehydrogenase (LDH). PFK, ME, G-6-PD, and CCE were elevated significantly after progesterone administration, while FAS and G-3-PD were unchanged. These changes may represent insulin effects. Progesterone treatment also results in increased PEPCK. This enzyme is associated with control of gluconeogenesis. PEPCK is considered to be a key rat-limiting enzyme in the "dicarboxylic acid shuttle." This finding may indicate an increased capability for glycogen formation.