Illustration of GAD67, VGAT, and CR immunostaining in substantia nigra (SN) and the surrounding regions in sham rat on coronal midbrain sections. Immunoreactivity (ir) of GAD and VGAT is high in substantia nigra par reticulata (SNR). The strong CR-ir displays in pars compacta (SNC) and lateralis (SNL) while weak CR-ir present in SNR.