Regulation of hepatic growth hormone receptors in coho salmon ( Oncorhynchus kisutch)

• Published in: General and comparative endocrinology Vol. 88; no. 2; pp. 243 - 252
• Main Authors: Gray, Elisabeth S., Kelley, Kevin M., Law, Samuel, Tsai, Robert, Young, Graham, Bern, Howard A.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.11.1992; Elsevier
• Subjects: Analysis of Variance; Animals; Biological and medical sciences; Blood Glucose - analysis; Body Height; Cell receptors; Cell structures and functions; Fasting - adverse effects; Fundamental and applied biological sciences. Psychology; Growth Hormone - physiology; Hormone receptors. Growth factor receptors. Cytokine receptors. Prostaglandin receptors; Hydrocortisone - physiology; Insulin-Like Growth Factor I - physiology; Liver - metabolism; Magnesium Chloride - pharmacology; Molecular and cellular biology; Receptors, Somatotropin - biosynthesis; Regression Analysis; Salmon - physiology; Sodium-Potassium-Exchanging ATPase - biosynthesis; Thyroxine - physiology; Weight Gain; Vertebrata; Regulation(control); Binding capacity; Adenohypophyseal hormone; Pisces; Liver; Oncorhynchus kisutch; STH; Hormonal receptor
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/0016-6480(92)90256-J

Factors potentially regulating hepatic growth hormone (GH) receptors in coho salmon ( Oncorhynchus kisutch) have been investigated. From December to June of the first year, relative changes in hepatic 125I-sGH binding and 35SO 4 incorporation by ceratobranchial cartilage were similar. Stunted salmon, which in seawater have elevated plasma GH yet fail to grow, showed lower hepatic 125I-sGH binding than did normally growing seawater salmon. However, MgCl 2 treatment of stunts' membranes to reveal total specific binding of 125I-sGH indicated receptor occupation by endogenous sGH. Total specific 125I-sGH binding was low in seawater stunts and remained low if these fish remained unfed after return to fresh water, but increased approximately twofold upon feeding. Total specific binding in fasted salmon in fresh water showed a trend toward decreased levels by 1 week; by 3 weeks, binding was 40% lower than in fed fish. There was a positive correlation ( r = 0.600) between condition factor and total specific binding in fed and fasted salmon in fresh water. Two weeks after hypophysectomy total speck binding was 50% lower than in sham-operated control salmon, indicating pituitary regulation of GH receptors. GH treatment reduced both free and total 125I-sGH binding in salmon examined 24 hr after treatment. Treatment with recombinant bovine insulin-like growth factor I, thyroxine, or cortisol did not affect free 125I-sGH binding. Both the pituitary and nutrition appear to be prime regulators of hepatic GH receptors in coho salmon.