The localization and origin of somatostatin-containing fibers in an auditory brainstem nucleus

Immunoreactive perikarya and terminals have been visualized in the rat brainstem using antibodies raised against somatostatin 14 and somatostatin 28 (4-14) in a peroxidase antiperoxidase procedure. Labeling was observed in several areas of the brainstem, including the solitary nucleus, the dorsal lateral lemniscus, the ventral cochlear nucleus, several areas of the reticular formation, the nucleus of the spinal trigeminal tract, and the locus ceruleus. There was no obvious difference obtained with antisera against SS 14 and SS 28 (4-14). Several auditory areas were found to contain SS in discrete sub-groups of perikarya and terminals, suggesting the existence of one or more specific SS-containing auditory pathways. The origin of the SS-positive terminals in the medial nucleus of the trapezoid body was investigated using thermal and chemical lesions. It was concluded that these terminals originate from a specific SS-positive group of perikarya located either in or adjacent to the medial portion of the nucleus of the dorsal lateral lemniscus.