vglut2 and gad expression reveal distinct patterns of dual GABAergic versus glutamatergic cotransmitter phenotypes of dopaminergic and noradrenergic neurons in the zebrafish brain.
Bottom Line: Our results show that most dopaminergic neurons also express GABAergic markers, including the dopaminergic groups of the olfactory bulb (homologous to mammalian A16) and the subpallium, the hypothalamic groups (A12, A14), the prethalamic zona incerta group (A13), the preoptic groups (A15), and the pretectal group.All together, our results demonstrate that all catecholaminergic groups in zebrafish are either GABAergic or glutamatergic.We compare our results with those that have been described for mammalian systems, discuss the phenomenon of transmitter dualism in the context of developmental specification of GABAergic and glutamatergic regions in the brain, and put this phenomenon in an evolutionary perspective.
Affiliation: Developmental Biology, Institute of Biology I, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104, Freiburg, Germany.Show MeSH
Mentions: The most rostral Otp-dependent DA neurons (larval group 2; Fig. 5B) expressed vglut2 (Fig. 5D–D3). These neurons, furthermore, did not express gad despite their proximity to gad-expressing cells (Fig. 5C, see also Fig. 6C). The more caudally located Otp-dependent DA groups in the posterior part of the PT and posterior tuberal nucleus (PTN) also expressed vglut2b during larval stages (larval groups 4–6; Fig. 5E,H) and in the mature brain (Fig. 5G–G3,J–J3). None of these groups expressed gad, whose expression domains were restricted to more ventral regions, namely, the dorsal and caudal zones of the periventricular hypothalamus (Fig. 5F,I).
Affiliation: Developmental Biology, Institute of Biology I, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104, Freiburg, Germany.