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Dietary cholesterol modulates Δ6 and Δ9 desaturase mRNAs and enzymatic activity in rats fed a low‐EFA diet
Author(s) -
Brenner Rodolfo R.,
Bernasconi Ana M.,
González María S.,
Rimoldi Omar J.
Publication year - 2002
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s1145-002-0905-3
Subject(s) - cholesterol , medicine , endocrinology , enzyme , sterol o acyltransferase , microsome , biology , campesterol , enzyme assay , linoleic acid , biochemistry , chemistry , fatty acid , sterol , lipoprotein
The effects of a 1% addition of cholesterol to a diet low in EFA on FA desaturases were examined. The administration of cholesterol markedly increased the esterified cholesterol content in microsomes and total liver lipids from the first day, whereas the proportion of free cholesterol remained unaltered throughout the treatment. An excellent homeostasis in the free cholesterol content was apparently evoked by the acyl‐CoA cholesterol acyltransferase. The cholesterol esters were mainly oleate, palmitate, and stearate, and the addition of cholesterol increased the relative proportions of cholesterol palmitoleate and oleate. The addition of cholesterol to a low‐EFA diet induced, as in animals fed a high‐FFA diet, a marked increase in liver stearoyl‐CoA desaturase‐1 mRNA and enzyme activity. This increased activity apparently evoked a similar enhancement of palmitoleic and oleic acids in total and microsomal liver lipids. The cholesterol‐rich diet depressed the liver Δ6 and Δ5 desaturase activity. However, the abundance of Δ6 desaturase mRNA was not modified throughout the treatment. This indicates that the depressive effect is evoked at a step beyond that controlled by the mRNA level. The depression of both enzymatic activities was consistent with the decrease in the percentages of arachidonic acid and DHA in total and microsomal liver lipids. Taken together, these results indicate that through its modulating effect on the desaturases, dietary cholesterol may lead an animal or humaan fed low‐EFA diet to a true deficiency by the decreased synthesis of the highly polyunsaturated acids derived from linoleic and α‐linolenic acids.