Gonadotropin Releasing Hormone (GnRH) Triggers Neurogenesis in the Hypothalamus of Adult Zebrafish

Abstract

Recently, it has been shown in adult mammals that the hypothalamus can generate new cells in response to metabolic changes, and tanycytes, putative descendants of radial glia, can give rise to neurons. Previously we have shown in vitro that neurospheres generated from the hypothalamus of adult zebrafish show increased neurogenesis in response to exogenously applied hormones. To determine whether adult zebrafish have a hormone-responsive tanycyte-like population in the hypothalamus, we characterized proliferative domains within this region. Here we show that the parvocellular nucleus of the preoptic region (POA) labels with neurogenic/tanycyte markers vimentin, GFAP/Zrf1, and Sox2, but these cells are generally non-proliferative. In contrast, Sox2+ proliferative cells in the ventral POA did not express vimentin and GFAP/Zrf1. A subset of the Sox2+ cells co-localized with Fezf2:GFP, a transcription factor important for neuroendocrine cell specification. Exogenous treatments of GnRH and testosterone were assayed in vivo. While the testosterone-treated animals showed no significant changes in proliferation, the GnRH-treated animals showed significant increases in the number of BrdU-labeled cells and Sox2+ cells. Thus, cells in the proliferative domains of the zebrafish POA do not express radial glia (tanycyte) markers vimentin and GFAP/Zrf1, and yet, are responsive to exogenously applied GnRH treatment.

Constitutive Neurogenesis and Neuronal Plasticity in the Adult Cerebellum and Brainstem of Rainbow Trout, Oncorhynchus mykiss

“…The decrease in mitotic activity coincides in time with the decrease in DC labeling [ 52 ]. A growing body of evidence suggests that aNSPCs are sensitive to endocrine signals [ 54 ], specific sensory modulation [ 55 ], social interactions [ 56 ], nutrient availability [ 57 ], and neurotrauma [ 8 , 9 , 13 , 20 , 22 , 58 ]. Depending on these factors, different populations of stem cells and progenitor cells can change their cycles of activity.…”

Shedding a Light on Dark Genes: A Comparative Expression Study of PRR12 Orthologues during Zebrafish Development

“…The same consideration can be extended to the several nuclei in the ventral diencephalon, where both prr12a and prr12b are expressed. These nuclei, including the anterior tuberal nucleus (ATN), periventricular nucleus of the posterior tuberculum (TPp), and the torus longitudinalis (TL), along with the Sox2+ anterior part of the parvocellular preoptic nucleus (Ppa), have recently been discovered to possess regenerative potential [30,31] (Figure 6C,H,L,N). Another unchanged aspect compared to developmental expression pattern is prr12 association with the visual system, winding among telencephalic and diencephalic nuclei in the adult brain, and also reinforced by transcripts presence in the optic (OT) and ventrolateral optic tracts (VOT) and the tectal torus longitudinalis (TL), which drives integration of visual information and spatial summation through a mechanism involving signals originated by retinal ganglion cells [32] (Figure 6G,H,L,M,N).…”

Uncovering the spectrum of adult zebrafish neural stem cell cycle regulators

“…Upon administration of estrogen to female zebrafish a reduction in cell proliferation in multiple brain regions has been reported, with the greatest impact in the dorsal/ventral telencephalon, preoptic area, hypothalamus, and cerebellum ( Makantasi and Dermon, 2014 ). Within the niche of the preoptic area, animals treated with gonadotropin releasing hormone, but not testosterone produce an increase in cell division in non-RGC stem cell populations ( Ceriani and Whitlock, 2021 ). Alternatively, inhibiting aNSPCs residing in the hypothalamus using the serotonin blocker tryptophan hydroxylase attenuates aNSPC proliferation, illustrating the dependency of stem cells in this domain on serotonin ( Pérez et al, 2013 ).…”