Methods
Adult rats received Escherichia coli lipopolysaccharide (LPS) (7.5 mg/kg intraperitoneally), RU 38486 (a glucocorticoid antagonist; 10 mg/kg by gavage) 2 hours prior to LPS administration, antibody to tumor necrosis factor (TNF) (4 mg/kg intraperitoneally) prior to LPS administration, or ketorolac tromethamine (a prostaglandin synthesis inhibitor; 1 mg/kg intraperitoneally) followed by LPS administration. Mucosal GS activity was assayed 12 hours after LPS administration. In a separate set of studies, cultured intestinal mucosal cells (Caco-2) were exposed to LPS, interleukin 1 (IL-1), IL-6, TNF-, interferon-, prostaglandin E₂, or dexamethasone. Twelve hours later, GS activity was assayed and messenger RNA was extracted. The GS transcripts were labeled with a GS complementary DNA probe radiolabeled with phosphorus 32, were quantitated by phosphoimaging, and were normalized to β-actin.

Results
In vivo LPS treatment increased mucosal GS activity by 250%. Pretreatment with antibody to TNF or ketorolac did not inhibit the LPS-induced increase in mucosal GS, whereas pretreatment with RU 38486 attenuated the increase in gut GS activity by 60%. Lipopolysaccharide, IL-1, IL-6, TNF-, -interferon, and prostaglandin E2 did not increase GS activity in Caco-2 cells, whereas dexamethasone increased GS activity and messenger RNA 2.5-fold and threefold, respectively. These data indicate that cytokines and prostaglandins (prostaglandin E₂) do not regulate mucosal GS expression during endotoxemia. Glucocorticoids, however, stimulate GS gene expression directly.

Conclusions
This hormonally mediated response may support de novo mucosal GS during septic states when uptake of glutamine from the lumen and blood is decreased.

(Arch Surg. 1994;129:59-65)