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: For microscopic observation, larvae were mounted in 80% glycerol/PBS containing 1% agarose. Confocal z-stacks of whole-mount larvae and sectioned brains were recorded by using a Zeiss LSM 5 DUO laser scanning confocal microscope. Then z-projections from subsets of focal planes were generated with the Zeiss LSM software and exported as image format files. The images were assembled into figures and processed with the Adobe (San Jose, CA) Photoshop CS2 9.0 software. Adjustments to contrast and brightness were made by using the Photoshop Levels functions. All adjustments were made to whole images including the enlarged sections, except for Figures 1I1–I3, 3C1–C3, 3F1–F3, and 4F1–F3, for which in the whole enlarged section red and green levels were adjusted to better visualize red and green channel colocalization.
Affiliation: Developmental Biology, Institute of Biology I, Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104, Freiburg, Germany.