Electrophoretic determination of the expressions of NOD1 and NOD2 mRNAs (A and C). Vehicle (0) or S. pneumoniae (1 × 106 bacteria) was administered to the rats via intracisternal injection. At days 1 (D1), D2, and D3 postinfection, brain tissue homogenates were isolated for measurements of NOD1 (Panel A) and NOD2 (Panel C). The expressions of NOD1 and NOD2 mRNAs were quantified by densitometric analyses and normalized to β-actin expression (Panels B and D). The asterisks indicate statistically significant differences compared to the corresponding uninfected animals (p < 0.05).