Aromatic L-amino acid decarboxylase- and tyrosine hydroxylase-immunohistochemistry in the adult human hypothalamus

The distribution of cell bodies immunoreactive for tyrosine hydroxylase and aromatic L-amino acid decarboxylase was studied in the adult human hypotha lamus. Many neurons in the posterior (A11) and caudal dorsal hypothalamic a reas (A13) as well as in the arcuate (A12) and periventricular (A14) zone w ere immunoreactive for the two enzymes, suggesting that they were dopaminer gic. Numerous tyrosine hydroxylase-immunoreactive neurons, which were not i mmunoreactive for aromatic L-amino acid decarboxylase, could be seen in the paraventricular, supraoptic and accessory nuclei (A15) as well as in the r ostral dorsal hypothalamic area. These were considered to be non-dopaminerg ic. Conversely, large numbers of small neurons immunoreactive for aromatic L-amino acid decarboxylase but not for tyrosine hydroxylase, were identifie d in the premammillary nucleus (Ds), zona incerta (D10), lateral hypothalam ic area (D11), anterior portion of the dorsomedial nucleus (D12), suprachia smatic nucleus (D13), medial preoptic area and bed nucleus of the stria ter minalis (D14). In the human hypothalamus, besides dopaminergic cell bodies, there exists a large number of tyrosine hydroxylase-only and aromatic L-am ino acid decarboxylase-only neurons, whose physiological roles remain to be determined. (C) 1998 Elsevier Science B.V. All rights reserved.