Nitric oxide involved in the IL-1β-induced inhibition of fructose intestinal transport.

Interleukin-1β (IL-1β) is a pleiotropic cytokine produced by cells of the immune system and a large variety of other cell types including endothelial cells. It is released during inflammatory and infectious diseases, and possesses a wide spectrum of autocrine, paracrine and endocrine activities. The aim of this work was to examine the IL-1β effect on D-fructose transport across rabbit jejunum and try to identify the mediators implicated in this process. A sepsis condition was induced for 90 min after intravenous (iv) administration of IL-1β and body temperature was recorded. Studies on cellular intestinal integrity have not shown modifications of the epithelium and the basement membrane. D-fructose intestinal transport was studied in rabbit jejunum from control and treated animals and it was reduced in the latter ones. This cytokine decreased both the mucosal to serosal transepithelial flux and the transport across brush-border membrane vesicles of D-fructose. The inhibition was reversed by L-NAME (nitric oxide [NO] synthase inhibitor), but not by indomethacin (cyclooxygenase 1 and 2 inhibitor). Both inhibitors were administered iv 15 min before the IL-1β. The protein levels of GLUT5 were not changed in all animal groups and those of mRNA were even increased. In summary, these findings indicate that IL-1β, at the time assayed, induced a significant reduction in the relative intrinsic activity of GLUT5 and in this decrease are involved NO signalling pathways. In this way, blockage of D-fructose intestinal uptake by IL-1β may be playing an essential role in the pathophysiology of septic shock.