Genes regulated by NF-kappaB play an important role on secondary damage and repair after spinal cord injury (SCI). To assess the early effects of the pharmacological inhibition and overactivation of NF-kappaB, pyrrolidine dithiocarbamate (PDTC) or lipopolysaccharide were given to rats before or after SC contusion. The amount of spared SC tissue was higher (P < 0.05) at 24 h postinjury in rats post-treated with PDTC; both PDTC-treated rats showed no significant trend to decrease polymorphonuclear infiltrate. p65 subunit was present in inflammatory cells, neurons, and astrocytes at the injury site. These data support further investigation on functional effects of NF-kappaB inhibition in acute SCI.