TH and infection: At 8 hpi, infection with Gr− bacteria increased the expression of phenylalanine hydroxylase (DN6080_c0_g2_i4 ) (log 2FC = 2.53) and reduced the levels of tyrosine hydroxylase (log 2FC = − 2.90) and aromatic amino acid decarboxylase (AAD 2 (DN2173_c1_g1_i9) (log 2FC = 6.50) compared with the PBS control.