Distribution of cholecystokinin octapeptide in the cat brainstem: an immunocytochemical study.

Using an indirect immunoperoxidase technique, the cell bodies and fibers containing cholecystokinin octapeptide in the brainstem of the cat were located. A high density of immunoreactive perikarya was observed in the lateral tegmental field and retrorubral nucleus, whereas a moderate density was found in the nucleus incertus, periaqueductal gray and dorsal tegmental nucleus. The nuclei coeruleus, sagulum, interpeduncular, motor dorsal nucleus of the vagus and nucleus of the solitary tract had a low density of immunoreactive cell bodies. The densest network of immunoreactive fibers was observed in the interpeduncular nucleus. The nuclei coeruleus, sagulum, praepositus hypoglossi, cuneiform, dorsal and ventral nuclei of the lateral lemniscus, marginal nucleus of the brachium conjunctivum, dorsal motor nucleus of the vagus, lateral tegmental field, inferior colliculus, periaqueductal gray and nucleus of the solitary tract had a moderate density of immunoreactive fibers. Finally, scarce immunoreactive fibers were found in the nucleus of the brachium of the inferior colliculus, inferior central nucleus, nucleus incertus, retrorubral nucleus and dorsal tegmental nucleus.