Response of rat adrenal cholesteryl esters to cold stress

Abstract

Male rats were maintained on diets containing corn oil or hydrogenated coconut oil. The compositions of the adrenal cholesteryl esters were determined in control animals and in those subjected to cold stress (4 C for 30 min). Total sterol ester content was lower in the stressed rats. In those receiving corn oil there were selective decreases in 16∶1, 18∶2 and 20∶4(n−6) esters but not in 22∶4(n−6). In the coconut oil fed, essential fatty acid (EFA) deficient animals, the decreases in 20∶4(n−6) and 22∶4(n−6) were quite selective, but the concentrations of the cholesteryl esters of 20∶3(n−9) and 22∶3(n−9) were also selectively reduced in the stressed animals. Olive oil and corn oilethyl erucate were employed as dietary fats in a second experiment. Plasma corticosterone was lower in animal fed ethyl erucate and subjected to cold stress. Cholesteryl erucate was the major adrenal ester in animals receiving dietary erucate but it was not well utilized in animals subjected to stress. The cholesteryl esters of linoleate and arachidonate were preferentially utilized in both of these dietary groups. Cholesteryl arachidonate was selectively utilized in all four dietary groups studied and may constitute the preferred substrate for rat adrenal cholesteryl ester hydrolase.

Modification of in vitro rat adrenal corticosteroidogenesis by dietary fat

“…The fatty acid composition of the adrenal cholesteryl esters from the animals fed the different fat diets is shown in Table IV. The wide range of cholesteryl esters is obvious and is consistent with published work (1,8,11). The fatty acid compositions of the dietary fats (Table I) seemed to be reflected, to some extent, in the levels of the different cholesteryl esters, especially up to cholesteryl linoleate.…”

“…Cholesterol and cholesteryl ester contents of the adrenals were determined routinely by the colorimetric method of Sobez and Fernandez (7). Quantification of the cholesteryl esters was done by gas liquid chromatography, as described by Walker and Carney (8). Corticosterone and lipid materials recovered from the two plain Rf regions were determined colorimetrically after reaction with 2,5-diphenyl-3-(4-styrlphenyl)-tetrazolium-chloride (K & K Laboratories, Plainview, N.Y.)-an approach commonly referred to as the blue tetrazolium (BT) procedure, first described by Elliott and coworkers (9).…”

Cholesteryl ester hydrolase activity in adrenal homogenates from normal and essential fatty acid‐deficient female rats

“…Studies involving the direct measurement of adrenal cholesteryl ester hydrolase activity are few in number. Beckett and Boyd (20) did observe that cholesteryl erucate (22:1) was less readily hydrolyzed than cholesteryl oleate by rat adrenal homogenates, confirming earlier in vivo observations in cold-stressed rats (7). Much of the current information concerning the specificity of the adrenal enzyme has been obtained indirectly from measurements of net changes in cholesteryl ester concentration in vivo (6)(7)(8).…”

“…Beckett and Boyd (20) did observe that cholesteryl erucate (22:1) was less readily hydrolyzed than cholesteryl oleate by rat adrenal homogenates, confirming earlier in vivo observations in cold-stressed rats (7). Much of the current information concerning the specificity of the adrenal enzyme has been obtained indirectly from measurements of net changes in cholesteryl ester concentration in vivo (6)(7)(8). The present investigation is consistent with the earlier studies with esters of oleic, linoleic and arachidonic acids being pref-erenfially hydrolyzed (in relation to tissue concentration) by rat adrenal homogenates.…”

“…Hydrolysis of cholesteryl esters to free cholesterol occurs in response to ACTH as a result of increased cholesteryl ester hydrolase activity (4). Specific cholesteryl esters may be preferred substrates for this hydrolytic process (5)(6)(7)(8).…”