Chronic cortisol and the regulation of food intake and the endocrine growth axis in rainbow trout
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Figure 1
(A) Plasma cortisol (B) plasma ACTH and (C) pituitary pro-opiomelanocortin A2 (pomc-a2) mRNA expression in rainbow trout implanted intraperitoneally with a micro-osmotic pump containing either vehicle (Sham), 20 μg (Cort-I) or 40 μg cortisol/g BW (Cort-II). Cortisol treatments terminated at 34 days as indicated by the dashed line. The mRNA expression values are normalized with elongation factor 1α (ef1α) and the expression ratios are presented relative to the Sham 14-day treatment. Statistical differences between values were determined by a two factor ANOVA and Holm-Sidak post-hoc test: cortisol (treatment: P<0.001, time: P<0.001, treatment×time: P<0.001), ACTH (treatment: P<0.001, time: P<0.001, treatment×time: P<0.001) and pomc-a2 mRNA expression (treatment: P<0.001, time: P=0.001, treatment×time: P=0.322). Bars for a given parameter and treatment that do not share a common letter are different from one another. At a given time, a difference from the Sham treatment is indicated by * and a difference between the cortisol treatments is indicated by † (P<0.05). Values are means+s.e.m. (n=8).
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Figure 2
(A) Food intake, (B) mass gained and (C) specific growth rate in rainbow trout implanted intraperitoneally with a micro-osmotic pump containing either vehicle (Sham), 20 μg (Cort-I) or 40 μg cortisol/g BW (Cort-II). Cortisol treatments terminated at 34 days as indicated by the dashed line. Statistical differences between values were determined by a two factor ANOVA and Holm-Sidak post-hoc test: food intake (treatment: P<0.001, time: P=0.423, treatment×time: P=0.373), mass gained (treatment: P<0.001, time: P<0.001, treatment×time: P=0.007) and specific growth rate (treatment: P<0.001, time: P=0.103, treatment×time: P=0.802). Bars for a given parameter and treatment that do not share a common letter are different from one another. At a given time, a difference from the Sham treatment is indicated by * and a difference between the cortisol treatments is indicated by † (P<0.05). Values are means+s.e.m. (n=8).
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Figure 3
Brain hypothalamic area (A) neuropeptide Y (npy), (B) agouti-related protein (agrp), (C) pro-opiomelanocortin A2 (pomc-a2), (D) cocaine- and amphetamine-regulated transcript (cart), and (E) preoptic area corticotropin-releasing factor (crf), and (F) liver leptin-A1 (lep-a1) mRNA expression in rainbow trout implanted intraperitoneally with a micro-osmotic pump containing either vehicle (Sham), 20 μg (Cort-I) or 40 μg cortisol/g BW (Cort-II). Cortisol treatments terminated at 34 day as indicated by the dashed line. The mRNA expression values are normalized with elongation factor 1α (ef1α) and the expression ratios are presented relative to the Sham 14-day treatment. Statistical differences between values were determined by a two factor ANOVA and Holm-Sidak post-hoc test: npy (treatment: P<0.001, time: P<0.001, treatment×time: P=0.253), agrp (treatment: P=0.004, time: P=0.115, treatment×time: P=0.418), pomc-a2 (treatment: P=0.826, time: P=0.943, treatment×time: P=0.994), cart (treatment: P=0.319, time: P=0.875, treatment×time: P=0.441), crf (treatment: P<0.001, time: P=0.107, treatment×time: P=0.485) and lep-a1 (treatment: P<0.001, time: P=0.012, treatment×time: P=0.102) mRNA expression. Bars for a given parameter and treatment that do not share a common letter are different from one another. At a given time, a difference from the Sham treatment is indicated by * and a difference between the cortisol treatments is indicated by † (P<0.05). Values are means+s.e.m. (n=8).
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Figure 4
Effects of cortisol on leptin-A1 (lep-a1) mRNA expression in primary culture of rainbow trout hepatocytes. Hepatocytes were exposed to either control (containing 0.01% ethanol as vehicle), cortisol (100 ng/ml), or a combination of cortisol (100 ng/ml) and RU486 (1,000 ng/ml) and sampled 24 h after treatment. Statistical differences between values were determined by a one way ANOVA and Holm-Sidak post-hoc test. Bars that do not share a common letter are different from one another. Values are means+s.e.m. (n=6 independent fish).
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Figure 5
(A) Pituitary growth hormone 1 (gh1) and (B) gh2 mRNA expression, (C) plasma GH, and (D) liver GH receptor type 2 (ghr2) mRNA expression in rainbow trout implanted intraperitoneally with a micro-osmotic pump containing either vehicle (Sham), 20 μg (Cort-I) or 40 μg cortisol/g BW (Cort-II). Cortisol treatments terminated at 34 days as indicated by the dashed line. The mRNA expression values are normalized with elongation factor 1α (ef1α) and the expression ratios are presented relative to the Sham 14-day treatment. Statistical differences between values were determined by a two factor ANOVA and Holm-Sidak post-hoc test: gh1 (treatment: P=0.002, time: P<0.001, treatment×time: P<0.001), gh2 (treatment: P<0.001, time: P=0.055, treatment×time: P<0.001), plasma GH (treatment: P=0.007, time: P=0.986, treatment×time: P=0.582) and ghr (treatment: P=0.003, time: P<0.001, treatment×time: P<0.001). Bars for a given parameter and treatment that do not share a common letter are different from one another. At a given time, a difference from the Sham treatment is indicated by * and a difference between the cortisol treatments is indicated by † (P<0.05). Values are means+s.e.m. (n=8).
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Figure 6
(A) Liver insulin-like growth factor I (igf1) mRNA expression, (B) plasma IGF1, (C) IGF binding protein 1 (igfbp1) mRNA expression and (D) igfbp2 mRNA expression in rainbow trout implanted intraperitoneally with a micro-osmotic pump containing either vehicle (Sham), 20 μg (Cort-I) or 40 μg cortisol/g BW (Cort-II). Cortisol treatments terminated at 34 days as indicated by the dashed line. The mRNA expression values are normalized with elongation factor 1α (ef1α) and the expression ratios are presented relative to the Sham 14-day treatment. Statistical differences between values were determined by a two factor ANOVA and Holm-Sidak post-hoc test: igf1 (treatment: P<0.001, time: P=0.006, treatment×time: P=0.048), plasma IGF1 (treatment: P=0.148, time: P=0.719, treatment×time: P=0.003), igfbp1 (treatment: P<0.001, time: P=0.055, treatment×time: P=0.692) and igfbp2 (treatment: P=0.002, time: P=0.002, treatment×time: P=0.12). Bars for a given parameter and treatment that do not share a common letter are different from one another. At a given time, a difference from the Sham treatment is indicated by * and a difference between the cortisol treatments is indicated by † (P<0.05). Values are means+s.e.m. (n=8).
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Figure 7
(A) Plasma glucose, liver (B) glycogen and (D) lipid content, and white muscle (C) glycogen and (E) lipid content in rainbow trout implanted intraperitoneally with a micro-osmotic pump containing either vehicle (Sham), 20 g (Cort-I) or 40 μg cortisol/g BW (Cort-II). Cortisol treatments terminated at 34 days as indicated by the dashed line. Statistical differences between values were determined by a two factor ANOVA and Holm-Sidak post-hoc test: plasma glucose (treatment: P<0.001, time: P=0.007, treatment×time: P=0.014), liver glycogen (treatment: P<0.001, time: P=0.358, treatment×time: P=0.733), muscle glycogen (treatment: P=0.664, time: P=0.123, treatment×time: P=0.696), liver lipid (treatment: P<0.001, time: P=0.167, treatment×time: P=0.237) and muscle lipid (treatment: P=0.010, time: P=0.572, treatment×time: P=0.199). Bars for a given parameter and treatment that do not share a common letter are different from one another. At a given time, a difference from the Sham treatment is indicated by * and a difference between the cortisol treatments is indicated by † (P<0.05). Values are means+s.e.m. (n=8).
- © 2015 Society for Endocrinology
