Glucose =
Tolerance
test (GTT) and fasting insulin
FAST
Mice are fasted for 16 ho=
urs
overnight
Tag the cage cards indica=
ting the
start and end times of the fast.
Fasting insulin and GT=
T
<=
/p>
Prepare the animals and c=
ollect
blood for fasting insulin
- Label mice in the cages using a marker on their t=
ails
to quickly tell them apart.
- Weigh each mouse and use a razor blade nick the t=
ail.
- Collect blood in a heparaniz=
ed
capillary tube for the fasting insulin. You will need 35-50 mL
(approximately 1/2-3/4 of the way up the tube). Use a pipette to force=
the
blood from the capillary tube into a microfuge
tube. Keep tubes on ice.
- Take a blood glucose measurement using the glucometer. Record this measurement as time 0.
- Prepare glucose injections in insulin syringes. M=
ice
receive one unit (0.01cc) of a 20% dextrose solution per gram of body
weight.
Begin the GTT
- Inject glucose into IP cavity. Animals should be
injected approximately 30 seconds apart.
- Sample blood glucose at 15, 30, 60 and 120 minutes
using the glucometer. Mice should be sampl=
ed
approximately 30 seconds apart so that the sample times are accurate f=
or
each animal.
- Return mice to cages with food.
Measuring fasted insulin<=
/p>
- Spin down the whole blood samples at 14,000 rpm f=
or
10 minutes (4°C).
- Transfer serum to a fresh tube.
- You will need 12 m<=
/span>L
of serum to use with the ELISA insulin assay. (Use mouse insulin as a
standard and follow the protocol that comes with the kit)
- Tubes can be stored at -80°C
and processed later with other samples.