Contribution of energy intake and tissue enzymatic profile to body
weight gain in high fat fed rats.
Gayles, Ellis C., Michael J. Pagliassotti, Piper A. Prach, Thad A.
Koppenhafer, James O. Hill.
SECTION OF PEDIATRIC NUTRITION, AND CENTER FOR HUMAN NUTRITION,
UNIVERSITY OF COLORADO HEALTH SCIENCES CENTER, DENVER, CO. 80262.
APStracts 3:0300R, 1996.
The purpose of the current study was to examine the enzymatic profile
(phosphofructokinase [PFK], [beta]-Hydroxyacyl-CoA dehydrogenase
[HADH], and citrate synthase [CS]) in gastrocnemius muscle, heart and
liver in rats allowed ad libitum access to a high-fat diet (HFD, 45%
of kcal from corn oil). Male Wistar rats were fed a low-fat diet
(LFD, 12% of kcal from corn oil) for a 2 week baseline period after
which some continued on the LFD and others were placed on the HFD.
After 1 week on the HFD, rats were categorized as obesity-resistant
(OR), -intermediate (OI), or -prone (OP) based on body weight gain
(OR, lower tertile; OI middle tertile; OP upper tertile). At 1, 2 and
5 weeks rats from each group were sacrificed (n=9-14/group/time
point) following a 24hr fast. At the end of the 5 week dietary period
weight gain was 114.8+/-4.3 g in LFD, 125.2+/-3.7 g in OR, 147.1+/
-4.1 g in OI and 173.7+/-3.5 g in OP rats (OP>OI>OR, LFD,
p<0.001). Energy intake was highly correlated with weight gain
on the high fat diet at each time point (r>/=0.72, p<0.001).
After 1 week on the high fat diet significant correlations between
the ratio of PFK/HADH (an indication of the relative capacity for
glycolysis vs. [beta]-oxidation, r=0.4, p=0.03) and HADH/CS (an
indication of the capacity for [beta]-oxidation relative to total
oxidative capacity, r=-0.56, p=0.001) in the gastrocnemius muscle and
weight gain were observed. At week 2, significant correlations
between these ratios and weight gain were observed in the
gastrocnemius, liver and heart. In contrast, these ratios were not
significantly correlated with weight gain at 5 weeks. These results
suggest that rats most susceptible to weight gain on a high-fat diet
are characterized by a continuous increase in energy intake
(explaining 50% of the variance in weight gain), and an early tissue
enzymatic profile that favors carbohydrate over fat utilization.
Received 8 April 1996; accepted in final form 15 July 1996.
APS Manuscript Number R198-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996