 |
|
15th
World Congress Clinical Nutrition
19th
– 22nd September 2010 El Sokhna Resort - Egypt
|
 |
|
|
| |
 |
Copyright © 2010.
WCCN2010.COM
All rights reserved |
|
 |
 |
Colonic luminal content and epithelial cell phenotype are markedly modified by a high protein diet
Francois Blachier, M Andriamihaja, AM Davila, M Eklou-Lawson, N Petit, S Delpal, F Allek, A Blais, C Delteil, D Tomé
AgroParisTech/INRA, Nutrition Physiology & Ingestive Behavior Laboratory Paris, France.
|
Objective/Aim of the
study/Project: Hyperproteic diets
are used in human nutrition in order
to obtain body weight reduction.
Although increased protein ingestion
results in increased transfer of
undigested alimentary and endogenous
proteins from the small to the large
intestine, there is little
information on the consequences of
the use of such diets on the
composition of the large intestine
content and on the epithelial cell
phenotype.
Methods: Rats were
fed for 15 days either a
normoproteic diet (NP, 14% protein
in weight) or a hyperproteic
isocaloric diet (HP, 53% protein) .
Absorptive colonic epithelial cells
were observed by electron microscopy
and the luminal colonic content was
analyzed.
Results: The
absorbing colonocytes were
characterized by a 1.7 fold
reduction in the height of the
brush-border membranes (p<0.001)
after HP diet consumption when
compared with NP animals. This
coincided in the whole colon content
of HP animals with a 1.8 fold higher
mass content (p<0.01), a 2.2 fold
higher water content (p<0.025), a
5.2 fold higher protease activities
(p<0;05), a 5.5 fold higher ammonia
content (p<0.001) and a more than
twofold higher propionate, valerate,
isobutyrate and isovalerate content
(p<0.05) when compared with NP
animals. The basal oxygen
consumption of colonocytes was
similar in the NP and HP groups but
ammonia was found to provoke a
dose-dependent decrease of oxygen
consumption in the absorbing
colonocytes. Glutamine synthetase
activity which condenses ammonia and
L-glutamate was ten fold higher in
colonocytes than in small intestine
enterocytes and was 1.6 fold higher
in colonocytes recovered from HP
than NP animals indicating a likely
role of this enzymatic activity for
L-glutamine production in
colonocytes.
Conclusions: Our
data indicate that medium-term high
protein diet ingestion causes
spectacular changes on both the
colonic luminal environment of
colonocytes and on the phenotypic
characteristics of these cells. For
these reasons, they should be
considered with some caution in
humans since the maximal non
deleterious level of protein
ingestion is not known
|
|
| |
|
 |
|
:: :: :: :: |
|
