Cholesterol metabolism in rat adrenal gland during reversible endotoxic shock

The adrenal glands have a crucial role for survival during endotoxic shock. Cholesterol is the obligatory intermediary in corticosteroid biosynthesis; thus any alteration in either the availability of cholesterol or in the ability of the adrenal gland to use cholesterol would have a profound effect on corticosteroid production. We have studied the effect of Escherichia coli endotoxin on cholesterol metabolism, injecting lipopolysaccharide (1.6 mg/100 g body) from E. coli 0111:B4 into the tail vein of male Wistar rat. Previous studies from this laboratory have shown that this dose of lipopolysaccharide induces a reversible endotoxic shock. During reversible endotoxic shock there is an alteration in plasma cholesterol; plasma total-cholesterol levels increase mainly at 6-24 h post-lipopolysaccharide injection, whereas cholesterol in high-density lipoproteins shows no significant variations, except a slight but significant decrease at 24 h. The cholesterol content in adrenal gland is diminished in endotoxemic rat, this decrease is more important at 6-24 h after endotoxin injection. We have also measured the acyl-CoA:cholesterol O-acyltransferase (ACAT) and cholesterol-esterase (CEH) activity during endotoxic shock. ACAT activity decreases after lipopolysaccharide injection. ACAT activity in endotoxemic rats is approximately 35-40% of the activity in control rats. This decrease is due to a defect in the functional capacity of the enzyme, since with exogenous cholesterol there is no significant variation in the ACAT activity. CEH activity, in contrast, increases during endotoxic shock; it shows a maximum (twofold the activity seen in control rats) at 6 h after lipopolysaccharide injection. These results show that lipopolysaccharide injection modifies cholesterol metabolism in plasma and in the adrenal gland, either directly or by mediators.