Stimulation of the activities of phosphatidate phosphohydrolase and tyrosine aminotransferase in rat hepatocytes by glucocorticoids

Modeling of Corticosteroid Effects on Hepatic Low-Density Lipoprotein Receptors and Plasma Lipid Dynamics in Rats

“…The concentrations of TG in naïve, untreated animals showed an obvious circadian rhythm, the exact regulation of which is unclear. One of the rate limiting enzymes for hepatic biosynthesis of TG is phosphatidate phosphohydrolase (PAP 2), which shows a circadian rhythm quite similar to TAT activity and is also known to be regulated by CS treatment (42). Besides possible regulation by PAP 2, these rats were fed ad libitum and therefore these circadian changes in TG may have been a result of their food intake.…”

Effects of corticosterone and insulin on enzymes of triacylglycerol synthesis in isolated rat hepatocytes

“…Most of the materials have been described in [7][8][9]11] except for bis-(p-nitrophenyl)phosphate which was obtained from Sigma Chemicals. The sample of partially purified phosphatidate phosphohydrotase was a gift from R. Hopewell and S. Butterwith.…”

“…Insulin has been suggested to stimulate triacylglycerol synthesis in the liver by increasing the supply of substrates for esterification, redirecting palmitoyl-CoA esters from oxidation to esterification [1], and by increasing glycerol 3-phosphate acyltransferase (EC 2.3.1.15) activity [2][3][4]. Stimulation of hepatic triacylglycerol synthesis by glucocorticoids has been mainly attributed to increases in phosphatidate phosphohydrolase (EC 3.1.3.4) activity [5], which has been demonstrated with isolated perfused livers [6] and hepatocytes [7]. The corticosterone-induced stimulation of phosphatidate phosphohydrolase activity has been shown to be inhibited by insulin [8].…”

Effects of glucocorticoid hormones on lipid-synthetic enzymes from different adipose tissue regions and from liver

“…Steroid hormones act at the level of nuclear chromatin, as described elsewhere (23,24). Hence, it is not surprising that inhibitors of protein synthesis abolish glucocorticoid-stimulated cytosolic phosphatidate phosphohydrolase activity in isolated rat hepatocytes (25). Even more specific for glucocorticoid-induced new protein synthesis in rat liver and epididymal adipose tissue were earlier studies with antibodies against fatty acid synthetase (4).…”