NF-κB activation mediates LPS-or zymosan-induced hypotension and inflammation reversed by BAY61-3606, a selective Syk inhibitor, in rat models of septic and non-septic shock.

We have previously demonstrated that the activation of the spleen tyrosine kinase (Syk)/inhibitory-κB (IκB)-α/nuclear factor-κB (NF-κB) p65 signalling pathway contributes to hypotension and inflammatory response in a rat models of zymosan (ZYM)-induced non-septic shock. The purpose of this study was to further examine the possible mechanism underlying the effect of inhibition of Syk by BAY61-3606 via NF-κB activity at the level of nuclear translocation regarding the production of vasodilator and proinflammatory mediators in lipopolysaccharide (LPS) (septic)- and ZYM (non-septic)-induced shock. Administration of LPS (10 mg/kg, ip) or ZYM (500 mg/kg, ip) to male Wistar rats decreased mean arterial pressure and increased heart rate that was associated with an increase in the activities of cyclooxygenase and nitric oxide synthase, tumour necrosis factor-α, and interleukin-8 levels, and NF-κB activation and nuclear translocation in sera and/or cardiovascular and renal tissues. BAY61-3606 (3 mg/kg, ip), the selective Syk inhibitor, given 1 hour after LPS- or ZYM injection reversed all the above-mentioned effects. These results suggest that Syk contributes to the LPS- or ZYM-induced hypotension and inflammation associated with transactivation of NF-κB in septic and non-septic shock.