Two populations of somatostatin-immunoreactive neurons in the guinea pig striatum

Two populations of neurons displaying somatostatin-like immunoreactivity were detected immunohistochemically in the guinea pig striatum using a monoclonal antibody. Sparse, well-stained neurons similar to those described in other species were observed throughout the guinea pig caudate-putamen. These neurons contained both neuropeptide Y and NADPH-diaphorase in addition to somatostatin. A second large population of somatostatin immunoreactive neurons in which these other substances did not coexist was found within the putamen.