Different stressors induce differential responses of the CRH-stress system in the gilthead sea bream (Sparus aurata)

Abstract

The hypothalamus-pituitary-interrenal (HPI) axis, involved in the regulation of the neuroendocrine stress responses, presents important players such as corticotropin-releasing hormone (CRH, generally considered as the initiator of this pathway) and CRH-binding protein (CRH-BP, considered as an antagonist of CRH function). CRH and CRH-BP full-length cDNA sequences were obtained from Sparus aurata by screening a brain cDNA library, and their phylogenetic analysis as well as their roles during acute and chronic stress responses were assessed. mRNA expression levels and plasma cortisol concentrations were measured by RT qPCR and ELISA, respectively, in S. aurata juveniles submitted to: i) different environmental salinities in a short-time course response; and ii) food deprivation during 21 days. In addition, osmoregulatory and metabolic parameters in plasma corroborated a clear reorganization depending on the stress source/period. Salinity transfer induced stress as indicated by enhanced plasma cortisol levels, as well as by up-regulated CRH and down-regulated CRH-BP expression values. On the other hand, food deprivation did not affect both expression levels, although plasma cortisol concentrations were enhanced. These results suggest that different stressors are handled through different stress pathways in S. aurata.

Starving/re-feeding processes induce metabolic modifications in thick-lipped grey mullet (Chelon labrosus, Risso 1827)

“…This high plasma cortisol level is related to the redistribution of energy during a stress response. Similar results were found in S. senegalensis suggesting that cortisol may play a functional role in the energetic turnover (Polakof et al, 2006;Costas et al, 2011;Wunderink et al, 2012;Martos-Sitcha et al, 2014). HK and PK activities were maintained during 21 days of food deprivation.…”

“…Plasma cortisol levels were measured by Enzyme Immune-Assay (EIA) using microtiter plates (MaxiSorp™, Nunc, Roskilde, Denmark) as previously described for other teleost species (Martos-Sitcha et al, 2014). Steroids were extracted from 5 μL plasma in 100 μL RB (10% v/ v PPB (Potassium Phosphate Buffer) 1 M, 0.01% w/v NaN 3 , 2.34% w/v NaCl, 0.037% w/v EDTA, 0.1% w/v BSA (Bovine Serum Albumin)) and 1.2 mL methanol (Panreac), and evaporated during 48-72 h at 37°C.…”

Sedative effect of 2-phenoxyethanol and essential oil of Lippia alba on stress response in gilthead sea bream (Sparus aurata)

“…Plasma cortisol concentration (expressed in ng mL − 1 ) was measured by indirect enzyme immunoassay (EIA) adapted to a microplate, as previously described by Martos-Sitcha et al (2014) for this species. Steroids were extracted from 5 μL of plasma in 100 μL RB [10% v/v PPB (potassium phosphate buffer) 1 M, 0.01% w/v NaN 3 , 2.34% w/v NaCl, 0.037% w/v EDTA, 0.1% w/v BSA (bovine serum albumin)] and 1.2 mL methanol (Panreac), which were then evaporated for 48-72 h at 37°C.…”

Influence of stocking density on growth, metabolism and stress of thick- lipped grey mullet (Chelon labrosus) juveniles

“…Plasma cortisol levels were measured by Enzyme Immune-Assay (EIA) using microtiter plates (MaxiSorp™, Nunc, Roskilde, Denmark) as previously described by Martos-Sitcha et al (2014) for other teleost species. Steroids were directly extracted from 5 μL of the plasma in 100…”