ZFIN ID: ZDB-PUB-980624-10
Sequence and expression of glutamic acid decarboxylase isoforms in the developing zebrafish
Martin, S.C., Heinrich, G., and Sandell, J.H.
Date: 1998
Source: The Journal of comparative neurology   396: 253-266 (Journal)
Registered Authors: Heinrich, Gerhard, Martin, Stella C., Sandell, Julie H.
Keywords: glutamic acid decaroxylase; gamma-aminobuyric acid; in situ hybridization; Danio rerio; hindbrain
MeSH Terms:
  • Amino Acid Sequence
  • Animals
  • Axons/physiology
  • Base Sequence
  • Central Nervous System/embryology
  • Central Nervous System/metabolism
  • DNA, Complementary/metabolism
  • Embryo, Nonmammalian/metabolism
  • Embryonic Development
  • Gene Expression Regulation, Developmental/physiology*
  • Glutamate Decarboxylase/genetics*
  • Humans
  • In Situ Hybridization
  • Isoenzymes/genetics*
  • Mice
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Rats
  • Sequence Homology, Amino Acid
  • Zebrafish/embryology*
  • Zebrafish/metabolism
  • gamma-Aminobutyric Acid/metabolism
PubMed: 9634146 Full text @ J. Comp. Neurol.
We describe the isolation two glutamic acid decarboxylase (GAD) cDNAs from zebrafish with over 84% identity to human GAD65 and GAD67. In situ hybridization studies revealed that both GAD65 and GAD67 were expressed in the early zebrafish embryo during the period of axonogenesis, suggesting a role for GABA prior to synapse formation. Both GAD genes were detected in the telencephalon, in the nucleus of the medial longitudinal fasciculus in the midbrain, and at the border regions of the rhombomeres in the rostral hindbrain. In the caudal hindbrain, only GAD67 was detected (in neurons with large-caliber axons). In the spinal cord, both GAD genes were detected in dorsal longitudinal neurons, commissural secondary ascending neurons, ventral longitudinal neurons, and Kolmer-Agduhr neurons. Immunohistochemistry for gamma-aminobutyric acid (GABA) revealed that GABA is produced at all sites of GAD expression, including the novel cells in the caudal hindbrain. These results are discussed in the context of the hindbrain circuitry that supports the escape response. We conclude that fish, like mammals, have two GAD genes. The zebrafish GAD65 and GAD67 are present in identified neurons in the forebrain, midbrain, hindbrain, and spinal cord, and they catalyze the production of GABA in the developing embryo.