Dynamics of liver GH/IGF axis and selected stress markers in juvenile gilthead sea bream (Sparus aurata) exposed to acute confinement: differential stress response of growth hormone receptors.
The time courses of liver GH/IGF axis and selected stress markers were analyzed in juvenile gilthead sea bream (Sparus aurata) sampled at zero time and at fixed intervals (1.5, 3, 6, 24, 72 and 120 h) after acute confinement (120 kg/m(3)). Fish remained unfed throughout the course of the confinement study, and the fasting-induced increases in plasma growth hormone (GH) levels were partially masked by the GH-stress inhibitory tone. Hepatic mRNA levels of growth hormone receptor-I (GHR-I) were not significantly altered by confinement, but a persistent 2-fold decrease in GHR-II transcripts was found at 24 and 120 h. A consistent decrease in circulating levels of insulin-like growth factor-I (IGF-I) was also found through most of the experimental period, and the down-regulated expression of GHR-II was positively correlated with changes in hepatic IGF-I and IGF-II transcripts. This stress-specific response was concurrent with plasma increases in cortisol and glucose levels, reflecting the cortisol peak (60-70 ng/mL), the intensity and duration of the stressor when data found in the literature were compared. Adaptive responses against oxidative damage were also found, and a rapid enhanced expression was reported in the liver tissue for mitochondrial heat-shock proteins (glucose regulated protein 75). At the same time, the down-regulated expression of proinflammatory cytokines (tumour necrosis factor-alpha) and detoxifying enzymes (cytochrome P450 1A1) might dictate the hepatic depletion of potential sources of reactive oxygen species. These results provide suitable evidence for a functional partitioning of hepatic GHRs under states of reduced IGF production and changing cellular environment resulting from acute confinement.
Saera-Vila
Alfonso
A
Nutrition and Fish Growth Endocrinology, Institute of Aquaculture Torre de la Sal (CSIC), 12595 Ribera de Cabanes, Castellón, Spain.
Calduch-Giner
Josep Alvar
JA
Prunet
Patrick
P
Pérez-Sánchez
Jaume
J
D000818:Animals; D015415:Biomarkers; D001786:Blood Glucose / Q000032:analysis; D020378:Confined Spaces; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D013006:Growth Hormone / Q000097:blood; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006854:Hydrocortisone / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011986:Receptors, Somatotropin / Q000235:genetics / Q000378:metabolism*; D021541:Sea Bream / Q000254:growth & development / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D001786:Blood Glucose; D029941:Fish Proteins; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D014409:Tumor Necrosis Factor-alpha; C018551:glucose-regulated proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; D019363:Cytochrome P-450 CYP1A1; D006854:Hydrocortisone