A high-sucrose diet increases gluconeogenic capacity in isolated periportal and
perivenous rat hepatocytes.
Bizeau, Michael E., Jeffrey S. Thresher, and Michael J. Pagliassotti.
Exercise Science Research Institute, Arizona State University, Tempe, Arizona
APStracts 8:0017E, 2001.
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 a SU (68% sucrose) or starch (ST, 68% starch) 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«minus»1•mg«minus»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 palmitate (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
dihydroxyacetone (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 accompanied by significant increases in the
maximal specific activities of glucose-6-phosphatase (G-6-Pase) and
phosphoenolpyruvate carboxykinase (PEPCK) in both PP and PV cells. These data
suggest that the SU diet influences GNG in both 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 PEPCK.
Received 26 September 2000; accepted in final form 15 January 2001
APS Manuscript Number E446-0.
Article publication pending Am J Physiol Endocrinol Metab
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 27 February 2001