Distribution of catecholamine-containing neurons in the normal human hypothalamus.
We have studied the distribution of catecholamine-containing neurons in the hypothalamus of 8 normal adult human brains, using Schmorl's stain for melanin and immunohistochemical staining for tyrosine hydroxylase (TH). TH immunoreactive perikarya were found in the wall of the third ventricle, in the areas in which dopaminergic neuroendocrine neurons are found in other primate species. Many of these neurons contained melanin pigment, and the percentage increased with age. Other melanin-pigmented neurons in the same distribution did not stain for TH, suggesting that postmortem TH immunostaining may not be sufficiently sensitive to visualize all catecholaminergic neurons. A separate group of larger TH-positive perikarya was seen in the lateral hypothalamic area. These may correspond to the incerto-hypothalamic dopamine neurons in other primate species. Only rare melanin-pigmented neurons were seen in this cell group, even at 66 years of age. Our data indicate that the hypothalamic neuroendocrine dopamine neurons in the human brain are distributed in a pattern similar to that in other primate species, and that both postmortem tyrosine hydroxylase and melanin staining provide an incomplete but representative sampling of the periventricular-arcuate cell group.