الفهرس 
Introduction and Literature SurveyOnly 14 pages are availabe for public view
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Abstract
Summary & Conclusion
The present study was planned to investigate the
changes in gastric emptying and motility in aged rats and
their contribution to changes in food intake in addition to
the role of NO in gastric emptying.
The present study was performed on 42 male Sprague
Dawley rats (10 adults, B.W. 160-210 g) and (32 aged,
B.W. 300-475 g). The rats were randomly allocated into the
following two main groups;
1. Group I; 10 adult rats (9-12 months old).
2. Group II; comprised of 32 aged rats (18-30 months
old) randomized into the following 3 subgroups.
a) Aged untreated rats: 10 aged rats. These rats
were given normal saline daily by gavage in a
dose of 1ml/Kg B.W. for 14 days, used as control
group for L-arginine and L-NAME treated
groups.
b) Aged L-arginine treated rats: 11 aged rats
treated with the nitric oxide precursor; L-arginine
for two weeks. L-arginine was freshly dissolved
in normal saline prior to injection (300 mg/1 ml),
and then injected intraperitoneally in a dose of
300 mg/Kg B.W.
c) Aged L-NAME treated rats: 11 aged rats treated
with the NO synthase inhibitor; N omega-nitro-Larginine
methyl ester (L-NAME) for two weeks.
L-NAME was freshly dissolved in normal saline
prior to injection (100 mg/ 1 ml) and injected
intraperitoneally in a dose of 10 mg /Kg B.W.
Throughout the study period, the rats were examined
for body weight as well as daily food intake and at the end
of the study; the rats were studied for gastric emptying of
non digestible solid particles and gastric motility.
Results of the present study revealed that Gastric
emptying was not significantly different in aged untreated
rat group compared to the adult rat group as well as in the
L-NAME treated and L-arginine treated aged rat groups
compared to their untreated aged counterparts. Isolated
strips of gastric antrum were observed to exhibit periodic
activity during the recording time, the analysis of which
revealed significant increase in frequency of gastric
contraction waves in untreated aged rat group compared to
adult rat group, while no significant difference was
observed in wave frequency between both L-NAME and Larginine
treated aged rat groups and their untreated aged
counterparts. On the other hand, wave duration,
developed tension (mg/mg tissue) as well as motility
index / second were found to be insignificantly different in
untreated aged rat group from adult rat group as well as in
both L-NAME treated and L-arginine treated aged rat
groups from their untreated aged counterparts.
Final body weight of adult rats showed significant
increase than their initial body weight, while all aged rat
groups exhibited significant decrease in their final body
weight compared to their initial values. However,
compared to adult rats, initial and final body weights of
untreated aged rat group was significantly increased, but
when initial and final body weights of L-NAME and Larginine
treated aged rats were compared to their untreated
aged counterparts , no significant difference was observed.
Daily food intake at the fourteenth day was found to
be not significantly changed in all the studied rat groups
from their initial food intake. Average food intake
increased significantly in untreated aged rats compared to
adult rats and decreased significantly in L-NAME treated
aged rat group compared to untreated aged rat group.
However, L-arginine treated aged rat group exhibited
insignificant change in their average food intake compared
to their untreated aged counterpart.
Conclusion
The present study showed that healthy aging was not
associated with changes in gastric emptying or motility.
Stimulation or inhibition of NO synthesis exerted no
significant effect on gastric emptying or motility but
inhibition of NO synthesis diminished food intake and
enhanced weight loss in aged rats. Thus, delayed gastric
emptying or dysmotility should not be interpreted as
physiological changes with healthy aging and a search for a
pathological cause for these changes should be considered.