Biology Reference
In-Depth Information
5.2.6
Biochemical Analysis
Fasting plasma insulin concentrations were measured using the ultrasensitive rat
insulin ELISA kit as described by the manufacturer (Mercodia, Uppsala, Sweden).
Tissue insulin sensitivity was evaluated by the previously validated (Bonora et al.
2000
) homeostasis model assessment (HOMA) using the HOMA index of insulin
resistance (HOMA-IR) = fasting insulin (mU/L) × fasting glucose (mM)/22.5
(Matthews et al.
1985
) .
Plasma nonesterified fatty acids (NEFA) were measured at 546 nm using
NEFA-HR (2) Kit according to instructions from the manufacturer (WAKO,
Richmond, VA, USA) at 37°C.
Triglycerides were measured in 10 ml plasma or 50 mg liver tissue, hydrolyzed in
0.5 M KOH/85% ethanol at 60°C for 30 min (Kates
1986
) . After cooling, MgSO
4
was added to 0.1 M and samples were vortexed and centrifuged at 16,000 ×
g
for
20 min at 4°C. Glycerol was measured spectrophotometrically at 340 nm as described
(Wieland
1984
) .
High-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL)
cholesterol in rat plasma were measured at 450 nm using an ELISA Kit according
to instructions from the manufacturer (Novatein Biosciences, Cambridge, MA,
USA) at 37°C. Total cholesterol was calculated as HDL + LDL.
5.2.7
Statistical Analysis
Data are presented as means ± standard error of the mean (SEM). Statistical analy-
ses were carried out using Bonferroni corrected student's
t
-tests. The mRNA data
were log-transformed before statistical analysis in order to obtain a normal distribu-
tion. All statistical analyses were performed using SAS 9.2 (The SAS Institute,
Cary, NC, USA). A p value less than 0.05 was considered significant.
5.3
Results
5.3.1
Body Weight, Body Fat, Food Intake, and Water Intake
All animal groups demonstrated a steady weight gain rate (data not shown). No
significant differences in weight gain or total body fat were observed (Table
5.1
).
Interestingly, the fructose-fed groups had a decreased food intake, but also an
increase in water intake, making the total calorie intake equal due to the 10% fruc-
tose in the water (Table
5.1
). Due to the difference in water intake, the fructose-fed
animals obtained double the amount of taurine throughout the 26-week study period
compared to control. No effect of taurine upon food intake, weight gain, or body fat
was observed in either study.
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