Expression and cellular localization of PGRPs in the developing brain. Changes in striatal Pglyrp2 (a) and Pglyrp3 (b) protein levels during postnatal development. Protein levels were normalized to the Hsp90 protein levels and expressed relative to the adult group (that is, P60; n=4 per group). All data (a and b) are presented as means (±s.e.m.). *P<0.05, **P<0.01 and ***P<0.001 when compared with their respective adult groups (that is, P60). Distribution of Pglyrp2 in the cerebellum (c), frontal cortex (d–f) and hippocampus (g–i) at P3. Double immunofluorescence staining shows staining of Pglyrp2 (green) combined with either NeuN (a neuronal marker; red), Iba1 (a microglial marker; red), GFAP (an astrocyte marker; red) or calbindin (a marker for purkinje cells; red). The merged images show the colocalization of Pglyrp2 (green) and NeuN (red) in the frontal cortex (d) and hippocampus (g) and with calbindin (red) in the cerebellum (c). Note that Pglyrp2 is moderately colocalization with astrocytes (f and i), and with microglia to a lesser extend (e and h). Arrows indicate Pglyrp2-positive Purkinje cells (c), Pglyrp2-positive microglia (e and h) and Pglyrp2-positive astrocytes (f and i). The scale bars represent 50 μm. Hsp, heat shock protein; P, postnatal day; PGRP, peptidoglycan-recognition protein.