Endotoxin-induced gene expression differences in the brain and effects of iNOS inhibition and norepinephrine

Purpose We studied gene expression differences in brain homogenate, hippocampus, somatosensory cortex and cerebellum of rats suffering from sepsis-associated delirium and analyzed the effects of norepinephrine and 1,400 W (specific inhibitor of the inducible nitric-oxide synthase). Methods We applied microarray screenings to rat brain homogenate 1, 3 and 4.5 h after lipopolysaccharide (LPS, 5 mg/kg) or 0.9% NaCl treatment. Therapy groups were analyzed after 4.5 h. Validations and compartment specific investigations were carried out by real-time PCR. Results Most striking gene expression differences were seen 4.5 h after LPS administration, especially within the hippocampus (chemokines and endothelial cell-specific molecule 1). Norepinephrine resulted in a discrete chemokine up-regulation, while 1,400 W had hardly any effect. Conclusion Strongest gene regulations were found within the hippocampus. Norepinephrine showed a tendency of having a proinflammatory influence, while 1,400 W had no clear-cut effect onto the gene expression level.