ZFIN ID: ZDB-PUB-151007-11
Intraspinal serotonergic neurons consist of two, temporally distinct populations in developing zebrafish
Montgomery, J.E., Wiggin, T.D., Rivera-Perez, L.M., Lillesaar, C., Masino, M.A.
Date: 2016
Source: Developmental Neurobiology   76(6): 673-87 (Journal)
Registered Authors: Lillesaar, Christina, Montgomery, Jacob
Keywords: Kolmer-Agduhr, pet1, serotonin, spinal cord, tryptophan hydroxylase
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Embryo, Nonmammalian
  • Gene Expression Regulation, Developmental/physiology*
  • Green Fluorescent Proteins/genetics
  • Green Fluorescent Proteins/metabolism
  • Larva
  • Neurons/metabolism*
  • Serotonin/metabolism*
  • Spinal Cord/cytology*
  • Spinal Cord/growth & development
  • Transcription Factors/genetics
  • Transcription Factors/metabolism
  • Tryptophan Hydroxylase/genetics
  • Tryptophan Hydroxylase/metabolism
  • Zebrafish/anatomy & histology*
  • Zebrafish/growth & development*
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism
  • gamma-Aminobutyric Acid/metabolism
PubMed: 26437856 Full text @ Dev. Neurobiol.
Zebrafish intraspinal serotonergic neuron (ISN) morphology and distribution have been examined in detail at different ages; however, some aspects of the development of these cells remain unclear. Although antibodies to serotonin (5-HT) have detected ISNs in the ventral spinal cord of embryos, larvae, and adults, the only tryptophan hydroxylase (tph) transcript that has been described in the spinal cord is tph1a. Paradoxically, spinal tph1a is expressed transiently in embryos, which brings the source of 5-HT in the ISNs of larvae and adults into question. Because the pet1 and tph2 promoters drive transgene expression in the spinal cord, we hypothesized that tph2 is expressed in spinal cords of zebrafish larvae. We confirmed this hypothesis through in situ hybridization. Next, we used 5-HT antibody labeling and transgenic markers of tph2-expressing neurons to identify a transient population of ISNs in embryos that was distinct from ISNs that appeared later in development. The existence of separate ISN populations may not have been recognized previously due to their shared location in the ventral spinal cord. Finally, we used transgenic markers and immunohistochemical labeling to identify the transient ISN population as GABAergic Kolmer-Agduhr double-prime (KA") neurons. Altogether, this study revealed a novel developmental paradigm in which KA" neurons are transiently serotonergic before the appearance of a stable population of tph2-expressing ISNs. This article is protected by copyright. All rights reserved.