Tlr4 and Tlr9 mRNA expression is influenced by age. Tlr4 (A) and Tlr9 (B) mRNA levels were measured in the brains from untreated neonatal and weanling mice. Housekeeping gene expression was averaged using Gusb, Actb and Rpl32. Data are presented as mean ± SEM (n = 5 to 6 per group). Statistical analysis was completed by an unpaired t-test. **P < 0.01, ***P < 0.001.