The localization of glycine (GR) and adrenergic receptors (AdR) was examined in the rat brain using a monoclonal antibody against the affinity purified glycine receptor and a polyclonal antibody against purified beta2-AdR. GR were concentrated in the lower brainstem, whereas no immunoreactivity was observed in the diencephalon and forebrain except in a few diencephalic nuclei. The highest density was found in the cranial motor nuclei, reticular formation, parabrachial area, dorsal and ventral cochlear nuclei, and dorsal and ventral tegmental nuclei. On the other hand, AdR were widely but unevenly distributed in the rat brain. The present study further showed the presence of AdR in catecholaminergic terminals in the hypothalamus.