AJP - Gastrointestinal and Liver Physiology, Vol 273, Issue 1 62-G67, Copyright © 1997 by American Physiological Society
Ontogeny and location of HMG-CoA reductase, ACAT, and MGAT in human small intestine
N. Loirdighi, D. Menard, E. Delvin and E. Levy
Department of Nutrition, Hopital Sainte-Justine, Universite de Montreal, Quebec, Canada.
Because a few enzymes are in most tissues, enabling them to produce lipids
necessary for growth and differentiation, the development of their activity
in the intestine, an important organ of fat transport and metabolism, is of
great interest. In this investigation, the ontogeny and location of
3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase (the key regulatory
enzyme in the cholesterol pathway), acyl-CoA:cholesterol acyltransferase
(ACAT; responsible for cholesterol esterification), and monoacylglycerol
acyltransferase (MGAT; the more representative enzyme of the neutral lipid
pathway) were examined in the human fetal small intestine. The developing
gut exhibited high levels (pmol.mg-1.min-1) of HMG-CoA reductase (7.65 +/-
0.35), ACAT (16.98 +/- 1.12), and MGAT (689.74 +/- 37.54). Significant
positive correlations were recorded between fetal age (8-22 wk) and the
enzyme activities of HMG-CoA reductase in the proximal (P < 0.005) and
middle (P < 0.01) segments, ACAT in the distal segment (P < 0.03),
and MGAT in the proximal segment (P < 0.03) of the gut. Age-specific
changes were found in the location of the three enzymes in the contiguous
intestinal segments that were investigated. We concluded that the fetal
small intestine has substantial HMG-CoA reductase, ACAT, and MGAT activity,
which displays specific patterns during development.
