Differential expression of two glucocorticoid receptors in seabass (teleost fish) head kidney after exogeneous cortisol inoculation

Abstract

Stressful conditions include a prompt release of corticosteroid hormones which can mediate gene expression through glucocorticoid receptors (GR). Since two seabass (Dicentrarchus labrax) GRs have been cloned and sequenced from peritoneal cavity cells (DlGR1) and liver (DlGR2), a comparative amino acid sequence analysis that included Haplochromis burtoni HbGRs, was carried out and homologies disclosed. The DlGR1 and DlGR2 deduced aminoacid sequences showed 61% identity (I) and 70% similarity (S). Moreover, DlGR2 was similar to HbGR2b (69% I, 73% S), and the DlGR1 to HbGR1 (72% I, 78% S). In addition, we examined the expression of the DlGRs after exogeneous cortisol inoculation into the peritoneal cavity, mimicking stress effects. At various times after the administration (3 h, 24 h, 1 week), gene expressions was evaluated in head kidney by real-time PCR. In addition, immunoblotting and densitometry analyses were performed with antiDlGR1 antibodies. Although sea bass head kidney expressed both DlGR1 and DlGR2 they were differentially modulated by intraperitoneal implant of exogeneous cortisol.

Transcriptional stress responses to environmental and husbandry stressors in aquaculture species

“…In accordance with this finding, there are several studies supporting down-regulation of GR by cortisol in fish (Pottinger 1990;Maule & Schreck 1991;Shrimpton & Randall 1994); also, GR concentration decreases inversely with blood cortisol levels in gills of coho salmon O. kisutch (Shrimpton 1996). On the other hand, GR induced by cortisol was up-regulated in vitro Vazzana et al 2010), but this result remains in vitro only and needs to be verified in vivo.…”

“…On the other hand, GR induced by cortisol was up‐regulated in vitro (Sathiyaa & Vijayan ; Vazzana et al . ), but this result remains in vitro only and needs to be verified in vivo .…”

Seabream (Sparus aurata) long-term dominant-subordinate interplay affects phagocytosis by peritoneal cavity cells

“…In fish, the primary response to stress involves the activation of the hypothalamic-pituitary-interrenal axis, which leads to increased levels of adrenocorticotropic hormone, cortisol, catecholamine and several plasmatic parameters and physiological activities, including the immune response (Fevolden et al, 2002;Vizzini et al, 2007;Vazzana et al, 2008Vazzana et al, , 2010. In aquaculture stress induced by confinement and by a high-density population increases blood plasma levels of cortisol, glucose, and osmolarity and affect innate immune responses.…”

Elevated cortisol modulates Hsp70 and Hsp90 gene expression and protein in sea bass head kidney and isolated leukocytes

“…This stress hormone, synthesized by the head kidney interrenal cells, regulates osmolarity, metabolism and modulates immune responses [25,40,44]. Injection with exogeneous cortisol mimics stress effects including cortisol-modulated responses such as enhanced serum levels of glucose, lactate and osmolarity [3,42], challenging a differential gene regulation [35]. Following cortisol binding, intracellular glucocorticoid receptors (GR) can exert their activity on the expression of the target genes by ligand-dependent transcription factor [33].…”