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Gen Comp Endocrinol. 2010 Sep 15;168(3):401-7. doi: 10.1016/j.ygcen.2010.05.009. Epub 2010 May 31.

Acquisition of spontaneous electrical activity during embryonic development of gonadotropin-releasing hormone-3 neurons located in the terminal nerve of transgenic zebrafish (Danio rerio).

Author information

1
Department of Physiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA 90095, United States.

Abstract

There are multiple populations of gonadotropin-releasing hormone (GnRH) neurons that have distinct physiological and behavioral functions. Teleost fish have a population of GnRH3 neurons located in the terminal nerve (TN) associated with the olfactory bulb that is thought to play a neuromodulatory role in multiple physiological systems, including olfactory, visual, and reproductive. We used transgenic zebrafish in which the GnRH3 promoter drives expression of a green fluorescent protein to identify GnRH3 neurons during development in live embryos. Unlike with hypophysiotropic GnRH neurons of zebrafish, TN-GnRH3 neurons are of neural crest origin and are one of the first populations of GnRH neurons to develop in the early embryo. Using a combination of optical imaging and electrophysiology, we showed that during the first 3 days post-fertilization, TN-GnRH3 neurons increase in number, extend neural projections, move in association with tissue expansion, and acquire an adult-pattern of spontaneous action potential firing. Early during development, about half of the neurons were quiescent/non-firing. Later, at 3 days post-fertilization, there was an increase in the proportion of neurons showing action potential firing and an increase in the number of neurons that showed an adult-like tonic or beating pattern of action potential firing with a firing frequency similar to that seen in adult TN-GnRH3 neurons. This study represents the first neurophysiological investigation of developing GnRH neurons in live embryos--an important advancement in understanding their potential non-reproductive roles during embryogenesis.

PMID:
20515692
PMCID:
PMC2922451
DOI:
10.1016/j.ygcen.2010.05.009
[Indexed for MEDLINE]
Free PMC Article

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