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Growth hormone and its receptor in projection neurons of the chick visual system: retinofugal and tectobulbar tracts

M-L Baudet1, D Rattray, S Harvey

  • 1Department of Physiology, 7-55 Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.

Neuroscience
|July 10, 2007
PubMed

Insights

Growth hormone (GH) is present in the developing chick embryo visual system, including retinal ganglion cells and optic nerve pathways. This suggests GH acts as a local growth factor during early visual system development.

Area of Science:

  • Neuroscience
  • Developmental Biology
  • Endocrinology

Background:

  • Recent studies detected growth hormone (GH) in retinal ganglion cells (RGCs) of chick embryos.
  • The embryonic visual system's development is a complex process influenced by various signaling molecules.

Purpose of the Study:

  • To investigate the presence and distribution of GH within the developing chick embryo visual system.
  • To explore the potential role of GH as a local growth factor in the visual pathway.

Main Methods:

  • Immunohistochemistry was used to trace GH immunoreactivity.
  • Localization of GH mRNA and GH receptor (GHR) was examined.
  • Analysis included the optic fiber layer, optic nerve, optic chiasm, optic tract, and optic tectum.

Main Results:

  • GH immunoreactivity was identified throughout the visual pathway, from RGCs to the optic tectum.
  • GH and its mRNA were found in the optic tectum before synaptogenesis.
  • GH receptor (GHR) and a GH-responsive gene (GHRG-1) were also detected in these tissues.

Conclusions:

  • GH is produced and present within the embryonic chick visual system.
  • The co-localization of GH, GHR, and GH-responsive genes suggests GH acts locally as a growth factor.
  • GH may play a crucial role in the early embryonic development of the visual system.

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