Neuropeptides in the amygdala of controls, schizophrenics and patients suffering from Huntington's chorea: an immunohistochemical study.

The location of the neuropeptides methionine-enkephalin (ME), neurotensin (NT), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) within the amygdaloid complex of healthy human individuals, schizophrenics and patients suffering from Huntington's chorea was studied qualitatively by means of immunohistochemistry. VIP-like immunoreactivity (IR) was present predominantly in a dense cluster of fibers and terminals in the central amygdaloid nucleus. ME-IR was observed in fibers, terminals and cell bodies in the same subnucleus, exhibiting a characteristical distribution pattern. NT-positive cell bodies were situated within the center of the central amygdaloid nucleus, fibers and terminals being encountered mainly at the periphery. NPY-IR was found to be evenly distributed throughout the amygdala. Distribution and staining intensity of ME, NPY and NT in the amygdala showed no qualitatively recognizable difference between the normal and schizophrenic specimens, whereas VIP-IR appeared to be slightly increased in the central amygdaloid nucleus of schizophrenics. In the choreic cases, the considerably shrunken amygdala exhibited only very low staining intensity of the four investigated neuropeptides.