Biology Reference
In-Depth Information
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FIGURE 9.4
Postprandial triglyceridemic response and TAG secretion rate. (A) Postprandial
triglyceridemic response in mice gavaged with 200 ml of olive oil. (B) TG secretion rate in mice
gavaged with 200
m
l of olive oil.
an emerging imaging method, CARS microscopy, which allows direct visuali-
zation of CLDs in cells and tissues without fixation or staining (
Cheng, 2007
).
This chapter also includes biochemical and physiological methods for assessing
dietary fat absorption as these methods are needed in combination with the images.
Moreover, another objective of this chapter was to emphasize the dynamics dietary
fat absorption and the importance in capturing the progression using different
methods.
The first section of this chapter highlights methods for collecting intestine tissue
from mice for assessing CLD biology and dietary fat absorption. Because the small
intestine contains specific regions, with distinct purposes in dietary fat absorption,
clearly defining the region of the small intestine being studies is important. In addi-
tion, because the process of dietary fat absorption and the presence of CLDs within
enterocytes is part of a dynamic process that is dependent on diet composition, the
timing post meal and composition of the diet are essential in interpreting and com-
paring results from mouse to mouse and study to study (
Zhu et al., 2009
). Often stud-
ies are completed in animals in the fasting state or intestine tissue collected from
humans after fasting due to surgical procedures involved. Significant CLD accumu-
lation in enterocytes during fasting is likely only present when a significant block
in chylomicron synthesis or secretion is present such as in chylomicron retention
disease (
Peretti et al., 2010
).
CARS microscopy has several benefits over traditional imaging (
Cheng, 2007;
Evans & Xie, 2008
). One benefit is being able to detect molecular structures without
the need for labels or fixation of the sample. This is particularly beneficial for
imaging CLDs in cells and tissues because fixation procedures often result in lipid
extraction. In addition, labels for lipids are often not specific. A second benefit is that
CARS microscopy can be combined with fluorescence imaging for the investigation
