Human brainstem catecholamine neuronal anatomy as indicated by immunocytochemistry with antibodies to tyrosine hydroxylase

Abstract

Immunocytochemistry based on antibodies to tyrosine hydroxylase is used to identify catecholaminergic neurons in the human brain stem. An atlas is provided and the distribution of structures compared with that in other animals and with biochemical and catecholamine fluorescent data from humans. Broad agreement of results increases the confidence with which tyrosine hydroxylase-like immunoreactivity can be used to trace catecholaminergic pathways in human postmortem material. As compared to most studies of other animals there are striking increases in populations of upper pontine and mesencephalic catecholaminergic neurons in the human. Distinct cytoarchitectonic features, consistent differences in tyrosine hydroxylase immunoreactive staining intensity and regional variations in substance P innervation indicate complexity within the substantia nigra. Human catecholaminergic neurons are prominent in the midline of the ventral tegmentum and the upper parts of the central tegmental tracts. A bundle of tyrosine hydroxylase-immunoreactive axons runs between the latter regions and a cluster of smaller catecholaminergic neurons which lie in the oblique band of axons joining ventrolateral and dorsomedial medullary catecholaminergic groups. There are more catecholaminergic neurons within and closely related to the superior cerebellar peduncles than have been described in other species. Anatomically, the central compact nucleus of the locus coeruleus appears to be related to several nearby catecholaminergic cell groups. The data provided are being used as a basis for neuropathologic studies of human neurological diseases.