GABAergic Neurons and Their Modulatory Effects on GnRH3 in Zebrafish.
γ-Aminobutyric acid (GABA) is a major amino acid neurotransmitter in the vertebrate brain. To provide detailed information on the distribution of the GABA in zebrafish (Danio rerio), neurons were labeled with mCherry driven by the glutamic acid decarboxylase 67 (gad67) promoter. In the transgenic line Tg(gad67:mCherry), mCherry-positive gad67 cell bodies were predominantly localized to the olfactory bulb, pallial zones, subpallium zones, parvocellular preoptic nucleus, periventricular gray zone of optic tectum, torus semicircularis, posterior tuberculum, medial longitudinal fascicle, caudal zone of periventricular hypothalamus, and oculomotor nucleus. mCherry-positive fibers were widely distributed in the olfactory bulbs, subpallium, thalamus, ventral hypothalamic zone, tectum opticum, mesencephalon, and rhombencephalon. mCherry-positive neurons were also observed in the retina and the spinal cord. The anatomical relationships between GABAergic and gonadotrophin-releasing hormone 3 (GnRH3) neurons were investigated by crossing Tg(gad67:mCherry) fish with the previously established Tg(gnrh3:EGFP) transgenic line. GnRH3 cell bodies and fibers were contacted by GABAergic fibers directly in the ventral telencephalon and anterior tuberal nucleus. A subpopulation of GnRH3 neurons in the ventral telencephalic area was also labeled with mCherry, so some GnRH3 neurons are also GABAergic. GABAB receptor agonist (baclofen) and antagonist (CGP55845) treatments indicated that GABAB receptor signaling inhibited gnrh3 expression in larval fish but was stimulatory in adult fish. The expression of pituitary lhβ and fshβ was stimulated by intraperitoneal injection of baclofen in adult fish. We conclude that GABA via GABAB receptors regulates GnRH3 neurons in a developmentally dependent manner in zebrafish.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Yanlong
Y
Song
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Binbin
B
Tao
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Ji
J
Chen
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Shaoting
S
Jia
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Zuoyan
Z
Zhu
Department of Biology, University of Ottawa, Ottawa, Canada.
Vance L
VL
Trudeau
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Wei
W
Hu
D000818:Animals; D030801:Animals, Genetically Modified; D001418:Baclofen / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism; D058786:GABA-B Receptor Agonists / Q000494:pharmacology; D059330:GABAergic Neurons / Q000187:drug effects / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000187:drug effects; D015027:Zebrafish / Q000378:metabolism*
D037201:Follicle Stimulating Hormone, beta Subunit; D058786:GABA-B Receptor Agonists; D037101:Luteinizing Hormone, beta Subunit; D050794:STAT1 Transcription Factor; C448022:gonadotropin-releasing hormone-III; D007987:Gonadotropin-Releasing Hormone; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D001418:Baclofen; D011761:Pyrrolidonecarboxylic Acid