Neonatal versus weanling expression of neuroinflammatory genes in myeloid cells isolated from the CNS. At six hours after ic inoculation with PBS or LPS, brain homogenates from neonatal and weanling mice were fractionated on Percoll gradients, and mRNA expression levels were analyzed by qRT-PCR. mRNA expression of neuroinflammatory markers Ccl2 (A), Nos2 (B) and Slamf7 (C) were elevated in the myeloid fraction from LPS-inoculated neonatal mice. Il6 (D) and Tlr4 (E) mRNA were not significantly different between age groups, while Tlr9 (F) mRNA levels were increased in myeloid cells from weanling mice. n = 4 to 5 mice per group from combined experiments. Data are presented as mean ± SEM. Statistical analysis was completed by two-way analysis of variance with Tukey’s multiple comparisons test. Significant age-specific-differences in the response to LPS are shown: ***P < 0.001.