Aromatic L-amino acid decarboxylase-immunoreactive structures in human midbrain, pons, and medulla.
Level 5 - mechanism / opinion, no new human data
Laboratory immunohistochemical study on post-mortem human brain tissue
PubMed 19589383 · doi:10.1016/j.jchemneu.2009.06.010
What was done
Authors used immunohistochemistry to determine the localization of aromatic L-amino acid decarboxylase (AADC)-immunoreactive neurons and fibers in the adult human midbrain, pons, and medulla oblongata.
What was found
No quantitative numbers are reported in the abstract. Intense AADC immunoreactivity was found in presumptive serotonin cell bodies throughout all raphe nuclei and in ventral pontine and medullary areas. Moderate to strong staining was seen in presumptive dopamine cells in the mesencephalic reticular formation, substantia nigra, and ventral tegmental area, as well as presumptive noradrenergic cells in the locus coeruleus and subcoeruleus. Moderate staining was observed in A1/C1 presumptive adrenergic/noradrenergic areas in the medulla. Dorsal vagal AADC-positive neurons were fewer and stained more weakly than tyrosine hydroxylase (TH)-positive cells, while TH-positive neurons in the gelatinous subnucleus of the solitary nucleus lacked AADC immunoreactivity. Nonaminergic AADC-positive (D) neurons were barely detectable in the human brainstem.
Why it matters
This study provides an anatomical map of AADC localization in the human brainstem, establishing baseline distributions for monoamine synthesis and identifying species-specific differences regarding nonaminergic D neurons.
Limits
The abstract does not state the sample size (number of human brains examined), donor characteristics, post-mortem intervals, or tissue quality. Observations are purely qualitative without cell counts or statistical comparisons.
Cited by
- supports Dopamine- and serotonin-producing neurons are few in number and localized to discrete regions of the brainstem.