Differentiation and maturation of zebrafish dorsal root and sympathetic ganglion neurons

Abstract

The trunk neural crest of vertebrate embryos gives rise to dorsal root ganglion (DRG) sensory neurons and autonomic sympathetic neurons, among other derivatives. We have examined the development of DRG and sympathetic neurons during development in the zebrafish. We found that sensory neurons differentiate rapidly and that their overt neuronal differentiation significantly precedes that of sympathetic neurons in the trunk. Sympathetic neurons in different regions differentiate at different times. The most rostral population, which we call the cervical ganglion, differentiates several days before trunk sympathetic neurons. After undergoing overt neuronal differentiation, sympathetic neurons subsequently express the adrenergic differentiation markers dopamine beta-hydroxylase and tyrosine hydroxylase. A second population of adrenergic nonneuronal cells initially localized with cervical sympathetic neurons appears to represent adrenal chromaffin cells. In more mature fish, these cells were present in clusters within the kidneys. Individual DRG and sympathetic ganglia initially contain few neurons. However, the number of neurons in DRG and sympathetic ganglia increases continuously at least up to 4 weeks of age. Analysis of phosphohistone H3 expression and bromodeoxyuridine incorporation studies suggests that the increases in DRG and sympathetic ganglion neuronal cell number are due wholly or in part to the division of neuronal cells within the ganglia.

The bHLH transcription factorhand2is essential for noradrenergic differentiation of sympathetic neurons

“…1A,B, arrowheads) in wild-type embryos (Guo et al, 1999;Holzschuh et al, 2001;An et al, 2002) and a massive reduction of dbh-expressing cells in hands off mutant embryos (Fig. 1C,D,arrowheads).…”

“…As sympathetic ganglion development in the rostral trunk is initiated just before 2 dpf, the hands off mutation provided the opportunity to investigate the role of hand2 in sympathetic ganglion development. We focus mainly on the initial stages of ganglion development in 2 and 3 dpf embryos, involving the specification and differentiation of sympathetic neurons (Guo et al, 1999;Holzschuh et al, 2001;An et al, 2002;Stewart et al, 2004).…”

The Chemokine Stromal Cell-Derived Factor-1 Regulates the Migration of Sensory Neuron Progenitors

“…It is known that the size of the DRGs continues to increase after their initial formation, even continuing postnatally to some extent (Namaka et al, 2001;An et al, 2002;Le Dourain et al, 2004). We identified a population of dividing cells from embryonic DRGS and observed that, as with trunk MNCs, they could differentiate into a population of neurons with properties similar to those of polymodal nociceptors.…”

“…It is known that after formation of the DRGs, these ganglia contain a population of dividing cells that continues to contribute to their maturation (Namaka et al, 2001;An et al, 2002). We therefore attempted to culture such a population from the DRGs of E14 mice, a time at which ganglion formation is nearly complete.…”

Interrenal Organogenesis in the Zebrafish Model

“…16,39 Similar to the mammalian adrenal medulla, the chromaffin component of the interrenal organ is originated from the neural crest through sequential steps of differentiation. 45 In the zebrafish embryo, the trunk neural crest gives rise to dorsal root ganglion sensory neurons and autonomic sympathetic neurons. Sympathetic neurons from cervical ganglion subsequently express adrenergic differentiation markers dbh and tyrosine hydroxylase, and some migrate to the interrenal region to become endocrine chromaffin cells.…”