Messenger NJ et al. (1999), The neurotransmitter noradrenaline drives noggi...

XB-ART-13620

Dev Biol 1999 Jan 15;2052:224-32. doi: 10.1006/dbio.1998.9125.

Show Gene links Show Anatomy links

The neurotransmitter noradrenaline drives noggin-expressing ectoderm cells to activate N-tubulin and become neurons.

Messenger NJ , Rowe SJ , Warner AE .

???displayArticle.abstract???
Neurotransmitters regulate neuronal function in the nervous system and modulation of their synthesis, release, and binding by immature neurons and their targets is a major part of nervous system development. We propose that the neurotransmitter noradrenaline regulates neuronal fate during neurulation, before neurons have differentiated. The ability of noradrenaline to induce a neural fate was tested in naive ectoderm caps cut from late blastula stage Xenopus embryos. Noradrenaline (10(-6) M) did not switch on otx-2 or NCAM and did not induce the formation of cement glands. We conclude that noradrenaline cannot induce a neural fate. By contrast, 10(-8) M noradrenaline activated N-tubulin in ectoderm caps expressing the neural inducing molecule noggin by the time intact siblings had become mid-neurulae. Methoxamine, a specific alpha-adrenergic receptor agonist, also activated N-tubulin in noggin-expressing caps. The alpha-adrenergic receptor blocker prazosin inhibited both noradrenaline- and methoxamine-induced activation of N-tubulin. The neurotransmitters dopamine and 5-HT did not activate expression of N-tubulin. XA-1, Otx-2, X-Delta, and Xotch transcripts were not sensitive to noradrenaline. HoxB9, which indicates posteriorization, was not activated by noradrenaline. When intact siblings were at stage 27, many cells in noggin-expressing, noradrenaline-treated caps were stained by the neuron-specific mcAb3A10. We propose that noradrenaline is an important endogenous modulator of neuronal fate, driving noggin-expressing cells to become neurons by binding to alpha-adrenergic receptors and activating a cascade that culminates in the expression of the neuronal markers N-tubulin and 3A10.

???displayArticle.pubmedLink??? 9917358
???displayArticle.link??? Dev Biol

Species referenced: Xenopus laevis
Genes referenced: dll1 hoxb9 ncam1 nog notch1 otx2 tubb2b xa-1
???displayArticle.antibodies??? Neuronal Ab4

???attribute.lit??? ???displayArticles.show???

	FIG. 1. Noradrenaline is not a primary neural inducer. Ectoderm caps from late blastula stage embryos treated with noradrenaline and assayed at stage 17 (A) or stage 12/13 (B, C). E, intact embryos. C, ectoderm caps. NA, ectoderm caps treated with noradrenaline. n, noggin-expressing caps. n/NA, noggin caps treated with noradrenaline. (A) Noradrenaline does not induce expression of NCAM in naive ectoderm caps. (B) NA induces XA-1, but this is not prevented by prazosin. (C) NA does not induce Otx-2.
	FIG. 2. Noradrenaline induction of N-tubulin in noggin-expressing caps is prevented by the a-adrenergic receptor blocker prazosin. NA (102 6 M): (A) stage 30, (B) stage 17. (C) NA (1027 M), stage 17. (D) Dose–response relationship for induction of N-tubulin by noradrenaline. Note that 1028 MNA is sufficient.
	FIG. 3. 5-HT (A) and dopamine (B) do not induce N- tubulin. The a-adrenergic agonist methoxamine (M) induces N-tubulin and this induction is blocked by prazosin (C).
	FIG. 4. Noradrenaline does not influence expression of Xotch (A), X-Delta (B), or HoxB9 (C).
	FIG. 5. At stage 17, N-tubulin-expressing cells are not uniformly distributed in noggin-expressing, noradrenaline-treated ectoderm caps. (A) noggin-expressing ectoderm caps do not express N-tubulin. (B, C) Noradrenaline (1026 M) induces expression of N-tubulin. Cells in the outer layer do not express N-tubulin and N-tubulin-expressing cells are not distributed uniformly. The high-power image in C shows that N-tubulin-expressing cells are interspersed with nonexpressing cells. Bar 5 160 mm for A and B and 480 mm for C.
	FIG. 6. At stage 27, noradrenaline-treated noggin caps contain many N-tubulin-expressing cells. (A–C) noggin caps treated with 1026 M noradrenaline. (A) Low-power image to show typical internal organization of Na-treated caps. The N-tubulin-expressing cells are concentrated in one region of the cap. The cement gland (arrowed) lies to one side, in a region where the majority of cells do not express N-tubulin. (B, C) Sections through two other 1026 MNa-treated noggin caps photographed at higher power to show the organization of N-tubulin-expressing cells. Note that even in regions where N-tubulin-expressing cells are at high density, not all cells express N-tubulin. (D) noggin cap treated with 1026 MNA and prazosin. This is an example of a cap where prazosin abolished completely the ability ofNAto induce N-tubulin expression. (E) noggin cap that had not been treated with NA. Untreated noggin caps never contained N-tubulin-positive cells. The scattered dark cells apparent in D and E are pigmented. (F) High-power image to show the stellate shape of N-tubulin-expressing cells (arrow) within the noradrenaline-treated cap. Bar 5 200 mm for A, D, and E, 125 mm for B and C, and 40 mm for F.
	FIG. 7. mcAb3A10 staining reveals that by stage 27 noradrenalinetreated, noggin-expressing caps contain neurons. (A, B, C) noggin caps treated with 1026 M noradrenaline. 3A10-positive cells are present at high density with many short neurites. In A and C the region containing most neurites lies between the arrows. (D) noggin cap treated with 1027 Mnoradrenaline. The density of 3A10-positive cells is reduced, although neurites are clearly visible (arrow). A substantial proportion of the cap does not contain 3A10-positive cells. (E) Part of noggin cap treated with 1026 M noradrenaline and prazosin. The only 3A10-positive cells are present in a small part of the cap (arrows). (F) A noggin-expressing cap that had not been treated with noradrenaline. 3A10-positive cells are absent. Each image shows a projection through the frozen section constructed from six stacked 2-mmoptical sections. Bar 5 100 mm. (G) Neural tube marginal zone in an intact Xenopus embryo stained with 3A10. Note dense neurite staining with some neurites coursing into surrounding tissues (e.g., arrows). Single 4-mm optical section. Bar 5 50 mm.