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taurine has been added to many supplemented diets and energy drinks, the advantage
of taurine to treat diabetic patients has not been conclusively demonstrated.
Our previous experiments indicate that perinatal taurine depletion induces mild
hyperinsulinemia without hyperglycemia or glucose intolerance in adult female
Sprague-Dawley (SD) rats (Thaeomor et al.
2010
), and this hyperinsulinemia is
exacerbated by an acute inhibition of renin-angiotensin system (RAS). In these ani-
mals, a blunted baroreceptor reflex does not underlie these changes since the
baroreflex effect is abolished by an angiotensin-converting enzyme inhibitor capto-
pril. Some experiments suggest that the perinatal taurine supplementation induces
obesity and insulin resistance in adult rats (Hultman et al.
2007
) . Whether perinatal
taurine supplementation influences the insulin-glucose regulation through the RAS
has not been tested. In addition, many lines of evidence indicate that perinatal tau-
rine exposure programs adult function and disease in a sex-dependent manner
(Roysommuti et al.
2009b
). Thus, estrogen may contribute significantly in this phe-
nomenon. This study tests the hypothesis that in adult female rats, the RAS and
estrogen contribute to insulin resistance resulting from perinatal taurine imbalance.
8.2
Methods
8.2.1
Animal Preparation
SD rats were bred at the animal unit of Faculty of Medicine, Khon Kaen University
and maintained at constant humidity (60 ± 5%), temperature (24 ± 1°C), and light
cycle (06.00-18.00 h). Female SD rats were fed normal rat chow with 3% beta-
alanine (taurine depletion, TD), 3% taurine (taurine supplementation, TS), or water
alone (control, C) from conception to weaning (Fig.
8.1
). Their female offspring
were fed with the normal rat chow with either 5% glucose in tap water (TD with
glucose, TDG; TS with glucose, TSG; C with glucose, CG) or tap water alone
(TDW, TSW, CW) throughout the experiment.
To test the possible role of RAS, another six separated groups were treated with
captopril in drinking water (an angiotensin-converting enzyme inhibitor, 400 mg/l)
from 7 days before parameter measurements until the end of experiment (CW + Cap,
CG + Cap, TDW + Cap, TDG + Cap, TSW + Cap, TSG + Cap). In addition to test the
possible role of estrogen, six separated groups were treated with an estrogen recep-
tor antagonist (tamoxifen, 10 mg/kg/day, oral) since 7 days before the study
(CW + Tam, CG + Tam, TDW + Tam, TDG + Tam, TSW + Tam, TSG + Tam). Blood
chemistry and cardiovascular parameters were studied between 7 and 8 weeks of
age in conscious rats.
All experimental procedures were approved by the Animal Ethics Committee of
Khon Kaen University (Khon Kaen, Thailand) and were conducted in accordance
with the US National Institutes of Health guidelines.
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