AJP - Endocrinology and Metabolism, Vol 238, Issue 4 364-E370, Copyright © 1980 by American Physiological Society
Effect of insulin on in vitro intestinal fatty acid esterification in the rat
Y. F. Shiau and P. G. Holtzapple
We have previously shown that glucose metabolism plays an important role in
modifying intestinal fatty acid esterification. Because it is well known
that glucose metabolism is under insulin regulation, we examined the effect
of insulin on intestinal fatty acid esterification. Insulin pretreatment
led to a marked decrease in in vitro intestinal fatty acid esterification,
but this decrease was abolished by maintaining blood glucose above 80
mg/dl. Addition of insulin to the incubation medium failed to produce any
effect on intestinal fatty acid esterification. The decreased fatty acid
esterification on hypoglycemic rats was not associated with changes in
fatty acid uptake or lipid esterifying enzyme activities. However, there
was a significant increase in the production of volatile metabolites of
fatty acid. We conclude that 1) insulin itself has no effect on intestinal
fatty acid esterification, 2) the effects observed in this study are due to
insulin-induced hypoglycemia, 3) hypoglycemia does not alter intestinal
fatty acid uptake or intrinsic esterification activity, but leads to
preferential oxidation rather than esterification of fatty acid by the
small intestine, and 4) the critical blood glucose concentration needed to
maintain normal esterification in the rat was approximately at 80 mg/dl.
