A high-sucrose diet increases gluconeogenic capacity in isolated periportal and perivenous rat hepatocytes

A high-sucrose (SU) diet increases gluconeogenesis (GNG) in the Liver. The present study was conducted to determine the contribution of periportal (PP ) and perivenous (PV) cell populations to this SU-induced increase in GNG. Male Sprague-Dawley rats were fed an SU (68% sucrose) or starch (ST, 68% st arch) diet for 1 wk, and hepatocytes were isolated from the PP or PV region of the liver acinus. Hepatocytes were incubated for 1 h in the presence of various gluconeogenic substrates, and glucose release into the medium was used to estimate GNG. When incubated in the presence of 5 mM lactate, which enters GNG at the level of pyruvate, glucose release (nmol . h(-1) . mg(-1 )) was significantly increased by the SU diet in both PP (84.8 +/- 3.4 vs. 70.4 +/- 2.6) and PV(64.3 +/- 2.5 vs. 38.2 +/- 2.1) cells. Addition of palm itate (0.5 mM) increased glucose release from lactate in PP cells by 11.6 /- 0.5 and 20.6 +/- 1.5% and in PV cells by 11.0 +/- 4.4 and 51.1 +/- 9.1% in SU and ST, respectively. When cells were incubated with 5 mM dihydroxyac etone (DHA), which enters GNG at the triosephosphate level, glucose release was significantly increased by the SU diet in both cell types. In contrast , glucose release from fructose (0.5 mM) was significantly increased by the SU diet in PV cells only. These changes in glucose release were accompanie d by significant increases in the maximal specific activities of glucose-g- phosphatase (G-6-Pase) and phosphoenol pyruvate carboxykinase (PEPCK) in bo th PP and PV cells. These data suggest that the SU diet influences GNG in b oth PP and PV cell populations. It appears that SU feeding produces changes in GNG via alterations in at least two critical enzymes, G-6-Pase and PEPC K.