Burlingame, CA) with 0.02% 3,3-diaminobenzidine (DAB) tetrahydrochloride and 0.003% hydrogen peroxide. The other hemisphere received 5 μl pyrogen-free saline in the same manner, as a sham injection. Five nanograms LPS did not show positive cells (data not shown) as seen after saline injection (Fig. 1A). Twenty nanograms showed positive cells in only one animal (Fig. 1B). All animals that received 50 ng survived 3 days and they showed consistent Isolectin B4 staining localized in the somatosensory cortex with a minor involvement in the corpus callosum (Fig. 1C). Animals receiving 100 ng showed a mortality rate of 66% before 3 days and the surviving animal showed strong staining in the cortex and corpus callosum with a partial involvement of the striatum (Fig. 1D). Thus, we selected 50 ng for the subsequent experiments.
