Identification of differentially expressed genes in the zebrafish hypothalamic–pituitary axis

Abstract

The vertebrate hypothalamic-pituitary axis (HP) is the main link between the central nervous system and endocrine system. Although several signal pathways and regulatory genes have been implicated in adenohypophysis ontogenesis, little is known about hypothalamic and neurohypophysial development or when the HP matures and becomes functional. To identify markers of the HP, we constructed subtractive cDNA libraries between adult zebrafish hypothalamus and pituitary. We identified previously published genes and ESTs and novel zebrafish genes, some of which were predicted by genomic database analysis. We also analyzed expression patterns of these genes and found that several are expressed in the embryonic and larval hypothalamus, neurohypophysis, and/ or adenohypophysis. Expression at these stages makes these genes useful markers to study HP maturation and function. KeywordsAdenohypophysis; cell differentiation; hormone; hypothalamic-pituitary axis; hypothalamus; neurohypophysis; organ maturation; pituitary; subtractive cDNA library Results and DiscussionThe hypothalamic-pituitary axis (HP) is the main link between the central nervous system and endocrine system. The HP regulates hormone secretion during homeostasis, growth, reproduction, and several other physiological functions. Under control of the hypothalamus, the adenohypophysis (anterior pituitary lobe) produces and secretes hormones involved in these functions. This control occurs through the production of hypothalamic hypophysiotropic hormones that stimulate or inhibit synthesis and release of adenohypophysial hormones. The hypothalamus also secretes hormones such as vasotocin and oxytocin (in mammals), and Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptGene Expr Patterns. Author manuscript; available in PMC 2010 April 1. isotocin and vasopressin (in fish) through its neuronal projections into the neurohypophysis (Bentley, 1998;Unger and Glasgow, 2003).Several genes regulate induction, specification, survival, patterning, and cell differentiation in the adenohypophysis (reviewed in (Dasen and Rosenfeld, 2001;Pogoda and Hammerschmidt, 2007;Zhu et al., 2005). However, little is known about the genetic regulation of later hypothalamic and neurohypophysial development or even when the HP matures and becomes physiologically functional.To identify developmental markers of the HP, we constructed subtractive cDNA libraries between adult hypothalamus and pituitary and examined expression of these genes in embryos and larvae. We report the construction of these subtractive libraries ...

Direct and indirect roles of Fgf3 and Fgf10 in innervation and vascularisation of the vertebrate hypothalamic neurohypophysis

“…fgf10 is not expressed in the developing hypothalamo-hypophyseal system of the zebrafish, but functions elsewhere (Nechiporuk and Raible, 2008). However, from 18 hours post-fertilisation (hpf), fgf3 is expressed in the ventral hypothalamic floor, extending anteriorly to the prosp-NH (Toro et al, 2009), directly dorsal to AH precursors (Herzog et al, 2004). At 32 and 33 hpf, fgf3 expression persists in posterior-most cells of the prosp-NH, characterised by co-expression of crabp1a (Liu et al, 2005), and in a stripe of ventral hypothalamic cells just posterior to the prosp-NH (Fig.…”

Zebrafish pituitary gene expression before and after sexual maturation

“…The pituitary gland is a key regulator of body homeostasis during development. A few studies have examined pituitary gene expression during early developmental stages (Brinkmeier et al 2009, Toro et al 2009). Highthroughput RNA-seq has enhanced our ability to perform transcriptome analyses at a far higher resolution than current Sanger sequencing-and microarray-based methods.…”

“…Under these conditions, most of the zebrafish reached sexual maturity in our laboratory. Approximately 300 pituitaries were obtained from juvenile zebrafish at 45 dpf, as described previously (Toro et al 2009). An additional 200 pituitaries were dissected from adult zebrafish at 90 dpf.…”

Zebrafish as an innovative model for neuroendocrine tumors

“…Orthologs for several mammalian neurohormones have been identified and localized in zebrafish (Toro et al 2009, Lohr & Hammerschmidt 2011. Therefore, the zebrafish is a relevant model for human endocrine system, providing important insights particularly into the development of endocrine glands (Porazzi et al 2009).…”