This ChAc patient showed faint immunoreactivity in the caudate nucleus and globus pallidus with antibodies against the striatal neurotransmitters, methionine-enkephalin, leucine-enkephalin and substance P. The difference in patterns of neuronal vulnerability could reflect those in the mechanisms of neurodegeneration between ChAc and HD.
We report on an HD phenocopy with selective loss of preprotachykinin (PPT) neurons, dysfunction of surviving PPT neurons, preservation of preproenkephalin (PPE) neurons within the striatum, and greater loss of immunohistochemical staining for substance P in terminals of striatal neurons projecting to the substantia nigra, than in those projecting to the internal pallidal segment.
A marked reduction in both enkephalin and substance P messenger RNAs was detected in all regions of the caudate nucleus and putamen in Huntington's disease grades 2/3 when compared to controls; in the dorsal caudate few enkephalin or substance P messenger RNA-positive cells were detected.