The teleostean (zebrafish) dopaminergic system ascending to the subpallium(shiatum) is located in the basal diencephalon (posterior tuberculum)

Tyrosine hydroxylase immunohistochemistry is used to demonstrate catecholam inergic neuronal populations in the fore- and midbrain of adult zebrafish ( Danio rerio). While no catecholaminergic neurons are found in the midbrain, various immunoreactive populations were found in the diencephalon (hypotha lamus, posterior tuberculum, ventral thalamus, pretectum) and telencephalon (preoptic region, subpallium, olfactory bulb). The posterior tubercular ca techolaminergic cells include three cytological types (small round, large p ear-shaped, and bipolar liquor-contacting cells). Furthermore, the retrogra de neuronal tracers Dil or biocytin were applied to demonstrate ascending p rojections to the basal telencephalon (incl. the striatum). A double-label approach was used - together with tyrosine hydroxylase immunohistochemistry - in order to visualize neurons positive for tyrosine hydroxylase and a re trograde tracer. Double-labeled cells were identified in two locations in t he posterior tuberculum (i.e, small round neurons in the periventricular nu cleus of the posterior tuberculum and large pear-shaped cells adjacent to i t). They are interpreted as the teleostean dopaminergic system ascending to the striatum, since previous work [16] established that no noradrenergic n eurons exist in the forebrain of the adult zebrafish. (C) 2001 Elsevier Sci ence B.V. All rights reserved.