The distribution of GAD67-mRNA in the adult zebrafish (teleost) forebrain reveals a prosomeric pattern and suggests previously unidentified homologies to tetrapods.
We used in situ hybridization on sections to examine the distribution of GAD67-expressing cell populations in the entire forebrain of the adult zebrafish. GAD67 is predominantly expressed in the olfactory bulb (OB), all regions of the subpallium (including the dorsal, ventral, central, and lateral nucleus of the area ventralis [Vd, Vv, Vc, and Vl, respectively]), as well as preoptic (PPa, PPp, and PM), pretectal (PPd, PPv, PCN, PSp, and PSm), ventral (= pre-) thalamic (I, VM, and VL), hypothalamic (Hr, Hi, and Hc), preglomerular (P, PGa, PGl, PGm, and RT), and posterior tubercular (TPp and TPm) nuclei. Only scattered GAD67-expressing cells are seen in all pallial zones (Dm, Dd, Dc, Dl, and Dp) and in the previously unidentified bed nucleus of the stria medullaris (BNSM). The BNSM appears to be the adult teleostean derivative of the larval eminentia thalami (EmT). We identify the GAD67-positive entopeduncular nucleus proper (EN) as being homologous to the entopeduncular nucleus of nonprimate mammals. GAD67 is strongly expressed in the anterior thalamic nucleus (A). The anterior thalamic nucleus is laterally bordered by a distinct GAD67-expressing cell population, which we interpret as the previously unidentified reticular thalamic nucleus (RTN) of teleosts. Furthermore, we identified a GAD67-positive thalamic nucleus, the intercalated nucleus (IC), which is sandwiched between the GAD67-negative dorsal (DP) and central posterior (CP) thalamic nuclei. Overall, the distribution of GAD67-expressing cells highly resembles the distribution of gamma-aminobutyric acid (GABA)/GAD67-expressing cells found in the early zebrafish (teleost) forebrain and thus allows us to propose a prosomeric fate map of GABAergic cell populations.
Mueller
Thomas
T
Department of Biopharmaceutical Sciences, Programs in Human Genetics and Biological Sciences, School of Pharmacy, University of California, San Francisco, California 94143-2811, USA. MuellerT@pharmacy.ucsf.edu
Guo
Su
S
D000818:Animals; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D017403:In Situ Hybridization; D010784:Photomicrography; D016548:Prosencephalon / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013045:Species Specificity; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D012333:RNA, Messenger; D029961:Zebrafish Proteins; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1