P1 versus P12 ELISA titrations and immunostaining intensities of cerebral pro-inflammatory cytokines, IL-1β and TNF-α. TNF-α was not detected by ELISA at P1 but an up-regulation - weaker than the one observed for IL-1β - was detected at P12 after HI and LPS+HI exposures by ELISA (A) and IHC in both white and gray matters (E). No modulation of combined pro- and active forms of IL-1β was detected by ELISA between the different experimental conditions at P1 (B), whereas the active form (17 kDa) of IL-1β as detected by western blot was increased in LPS+HI condition (C, D). Some foci of increased IL-1 immunostaining were detected by IHC in brain exposed to HI or LPS+HI, at 48 h post-HI (F). At P12, IHC results confirmed an increased IL-1β expression localized especially in gray, and in a lesser extent in white matter, of brains exposed to HI and LPS+HI (F) and a TNF-α increase was detected only in the LPS+HI brains (E) at P1. Protein detection was performed by ELISA on 3 to 4 brains assayed in duplicate, at each time point under each experimental condition. IHC and western blot were performed at 48 h post-HI, in 3 to 4 brains in each experimental condition. *p < 0.05, **p < 0.01, ***p < 0.001, one-way ANOVA with Newman-Keuls post test, except for LPS versus control at P1 in gray matter using t test with Welch correction.