Immunostaining of NMDA receptors in PAG. Immunostaining was performed in the coronal midbrain slices containing the PAG. (A) Expression of NR2A in saline control, CFA, and CFA + Hyp treated mice. (B) Expression of NR2B in saline control, CFA, and CFA + Hyp treated mice. Scalebar (in B): A, B, 500 μM. DMPAG: Dorsomed periaqueductal gray; LPAG: Lateral periaqueductal gray.