Acclimation to different environmental salinities induces molecular endocrine changes in the GH/IGF-I axis of juvenile gilthead sea bream (Sparus aurata L.)

Abstract

To assess the role of the GH/IGF-I axis in osmotic acclimation of the gilthead seabream Sparus aurata, juvenile specimens were acclimated to four environmental salinities: hyposmotic (5 ‰), isosmotic (12 ‰) and hyperosmotic (40 and 55 ‰). The full-length cDNAs for both pituitary adenylate cyclase-activating peptide (PACAP) and prepro-somatostatin-I (PSS-I), the precursor for mature somatostatin-I (SS-I), were cloned. Hypothalamic PACAP and PSS-I, hypophyseal growth hormone (GH) and prolactin (PRL), and hepatic insulin-like growth factor-I (IGF-I) mRNA expression levels were analyzed in the four rearing salinities tested. PACAP and IGF-I mRNA values increased significantly in response to both 5 and 55 ‰ salinities, showing a U-shaped curve relationship with the basal level in the 40 ‰ group. Hypothalamic PSS-I expression increased strongly in the 55 ‰ environment. GH mRNA levels did not change in any of the tested environmental salinities. PRL mRNA maximum levels were encountered in the 5 and 12 ‰ environments, but significantly down-regulated in the 40 ‰. Plasma cortisol levels significantly increased in the 40 ‰ environment. These results are discussed in relation to the well-known high adaptability of Sparus aurata to different environmental salinities and the role of the GH/IGF-I axis in this process.

The Bromodomain testis-specific gene (Brdt) characterization and expression in gilthead seabream, Sparus aurata, and European seabass, Dicentrarchus labrax

“…The real-time PCR efficiencies were calculated from the slope, according to the equation E=10 [-1/slope] . Relative gene quantification was performed using the method of Pfaffl, 29 using β-actin (primers from Mohammed-Geba et al 30 ) and 18S rRNA (Martos-Sitcha et al . 31 ) as the internal control genes for S. aurata or β-actin [GenBank: AJ537421.1] and L13a (Mitter et al .…”

Molecular performance of Prl and Gh/Igf1 axis in the Mediterranean meager, Argyrosomus regius, acclimated to different rearing salinities

“…Kültz, 2013. Minute changes in the extracellular osmolality, together with the presence of some autocrine modulator proteins like Prl177 and Prl188, directly triggered Prl production in the European eel, S. 351 aurata, and the tilapias (Suzuki et al 1991;Uchida et al 2004;Mohammed-Geba et al 2015;Yamaguchi et al 2016). Moreover, it is noteworthy to mention that both plasma Prl levels and pituitary prl expression patterns corresponded in their upregulation in response to hyposmotic salinity in different perciform species, like O. mossambicus and S. aurata (Riley et al 2003;Laiz-Carrión et al 2009;Vargas-Chacoff et al 2009).…”

“…For this reason, more research on both euryhaline and stenohaline species to determine the widespread osmoregulatory actions of the Gh/Igf1 axis is required (Sakamoto and McCormick 2006;Mancera and McCormick 2007;Mohammed-Geba et al 2015).…”

Insulin-like growth factor 1 (IGF-1) regulates prolactin, growth hormone, and IGF-1 receptor expression in the pituitary gland of the gilthead sea bream Sparus aurata

“…However, growth hormone role in osmoregulation in non-salmonid teleosts is still under debate, with some reports referring to more active IGF-1 stimulation upon fish movement to hypersaline waters and consequent activation of osmoregulatory processes (McCormick 2001;Mancera and McCormick,2007;Tipsmark et al 2008;Mohammed-Geba et al, 2015). Differential regulation of growth hormone and prolactin is very well known in migratory fish during their migration or spawning periods (Mancera and McCormick., 1998;Persson et al, 1998;Sakamoto and McCormick., 2006;Makino et al, 2007).…”

“…We aimed with this work to clone the tyrosine-kinase receptor of the IGF-1 and to study the transcriptional responses of this receptor and of major hormonal transcripts in pituitary, these of GH and the PRL, that represent key hormonal controllers of fish osmoregulatory systems in general (Mancera and McCormick, 2007) and S. aurata in particular (e.g., Pérez-Sánchez, et al, 1994;Mancera et al, 2002), to gradually increasing concentrations of IGF-1. Very few studies were carried out reporting this regulation especially at the molecular level of IGF-1, mainly Eppler et al, 2007;Fruchtman et al 2002a,b;and Mohammed-Geba et al, 2015. immediately rinsed in µL of the freshly prepared pre-incubation medium to clean out blood, then directly transferred to other new µL of pre-incubation medium at 21 ºC in a sterile, lowcoating capacity, cell culture-specific 96 well-plate (Costar, USA) for hours. Serial dilutions were also prepared, using the incubation medium, from rhIGF-1 (recombinant human IGF-1, Sigma-Aldrich, Cat.…”