ZFIN ID: ZDB-PUB-080218-18
Early Development of Gonadotrophin-Releasing Hormone-I Neurones and the Role of GnRH-I as an Autocrine Migration Factor
Abraham, E., Palevitch, O., Ijiri, S., Du, S.J., Gothilf, Y., and Zohar, Y.
Date: 2008
Source: Journal of neuroendocrinology 20(3): 394-405 (Journal)
Registered Authors: Du, Shao Jun (Jim), Gothilf, Yoav, Zohar, Yonathan
Keywords: GnRH, Zebrafish, transgenic, neurone, migration
MeSH Terms: Animals; Animals, Genetically Modified; Autocrine Communication/physiology*; Axons/metabolism; Cell Movement/genetics* (all 24) expand
PubMed: 18208553 Full text @ J. Neuroendocrinol.
FIGURES   (current status)
Normal migration of the GnRH-I neurones during early development, from the olfactory region to the hypothalamus, is crucial for reproductive development in all vertebrates. The establishment of the GnRH-I system includes tangential migration of GnRH-I perikarya as well as extension of GnRH-I fibres to various areas of the CNS. The exact spatio-temporal nature of this process, as well as the factors governing it, are not fully understood. We studied the development of the GnRH-I system and the effects of GnRH-I knockdown using a newly developed GnRH-I:EGFP transgenic zebrafish line. We found that EGFP is specifically and robustly expressed in GnRH-I neurones and fibres. GnRH-I fibres in zebrafish began to extend as early as 26 hours post-fertilisation and by 4-5 days post-fertilisation (dpf) had developed into an extensive network reaching the optic tract, telencephalon, hypothalamus, midbrain tegmentum and hindbrain. GnRH-I fibres also innervated the retina and projected into the trunk via the spinal cord. GnRH-I perikarya were observed migrating along their own fibres from the olfactory region to the preoptic area (POA) via the terminal nerve ganglion (TNg) and the ventral telencephalon. GnRH-I cells were also observed in the trigeminal ganglion. The establishment of the GnRH-I fibre network was disrupted by morpholino-modified antisense oligonucleotides (MO) directed against GnRH-I causing abnormal fibre development and pathfinding, as well as anomalous GnRH-I perikarya localisation. These findings support the hypothesis that GnRH-I neurones migrate from the olfactory region to the POA and caudal hypothalamus. Novel data regarding the early development of the GnRH-I fibre network in the CNS and beyond is described. Moreover we show, in vivo, that GnRH-I is an important factor regulating GnRH-I fibre pathfinding and neurone localisation in an autocrine fashion.