Immunocytochemical localization on neuropeptides in the fornix of rat, monkey and man.

Using specific antisera and immunocytochemical methods VIP, CCK, substance P, methionine-enkephalin, neurotensin and somatostatin-like immunoreactive fibers were found within the fornix and fimbria in 3 species (rat, monkey and human). Neither methionine-enkephalin- nor substance P-containing cell bodies were located within the hippocampus and so fibers containing these peptides are presumably hippocampal afferents, probably arising in the septum or caudal hypothalamus. VIP, CCK, neurotensin and somatostatin fibers may be hippocampal efferents arising from cell bodies within the subiculum.