Effects of ketamine on proinflammatory cytokines and nuclear factor kappaB in polymicrobial sepsis rats

To explore the effects of ketamine on hemo-dynamics, plasma proinflammatory cytokine (TNF-alpha and IL-6) levels and nuclear factor kappa B (NF-kappaB) activation during polymicrobial sepsis.

Male Sprague-Dawley rats were subjected to cecal ligation and puncture (CLP) or sham operation. The rats were randomly assigned into four equal groups: sham CLP group, CLP group, ketamine (KT) I group and KT II group. Thirty minutes before CLP, ketamine (5 mg/kg per hour and 10 mg/kg per hour, respectively) was infused continuously through the left femoral vein cannula in KT I group or KT II group. Sham CLP group and CLP group received 0.9% saline only (5 mL/kg per hour). The right femoral artery was cannulated to monitor mean arterial pressure (MAP) and heart rates (HR),and draw blood samples. The proinflammatory cytokine (TNF-alpha and IL-6) levels of plasma were measured using enzyme-linked immunosorbent assays (ELISA). The hepatic NF-kappaB activation was determined by Western blot and HPIAS 2000 image analysis system. Twenty hours after CLP, the rats were killed by right femoral artery phlebotomization.

CLP produced progressive hypotension, and a first increase followed by a decrease in HR. The hypotension was prevented, and the HR was slightly steady in ketamine treated rats. TNF-alpha levels of plasma reached a peak value at 2 h after CLP. Ketamine (KT I group or KT II group) caused a significant decrease compared with CLP group at 2, 5 and 9 h time points after CLP (14.3 +/- 1.9 vs 4.3 +/- 0.9, 9.7 +/- 1.4 vs 4.3 +/- 0.9; 9.3 +/- 1.5 vs 4.3 +/- 0.9, 8.7 +/- 1.4 vs 4.3 +/- 0.9; 6.0 +/- 1.5 vs 5.0 +/- 1.7, 5.3 +/- 0.8 vs 5.0 +/- 1.7; P < 0.01, respectively). The IL-6 levels of plasma firstly ascended and then descended in CLP group, and reached a peak value at 9 h after CLP. Ketamine (KT I group or KT II group) caused a significant decrease compared with CLP group at 5, 9 or 20 h after CLP (135.0 +/- 52.6 vs 60.0 +/- 16.3, 112.5 +/- 52.6 vs 60.0 +/- 16.3; 410.0 +/- 68.7 vs 62.5 +/- 12.5, 250.0 +/- 28.0 vs 62.5 +/- 12.5; 320.0 +/- 25.9 vs 52.5 +/- 10.1, 215.0 +/- 44.6 vs 52.5 +/- 10.1; P < 0.05, respectively). The IL-6 levels of plasma in KT II group were lower than those of KT I group at 9 h after CLP (250.0 +/- 28.0 vs 410.0 +/- 68.7; P < 0.05). In addition, CLP increased hepatic NF-kappaB expression compared with sham CLP. Ketamine suppressed NF-kappaB activation in a dose-dependent manner at 4 h after CLP (237.7 +/- 3.5 vs 246.9 +/- 3.1; P < 0.05).

Ketamine stabilizes the hemodynamics, attenuates the proinflammatory cytokine responses, and inhibits hepatic NF-kappaB activation. These findings suggest that ketamine has protective effects against polymicrobial sepsis in rats.