[Zinc and the growth hormone system].
Chronic zinc nutritional deficiency constantly causes delay in pondero-statural growth. The mineral controls GH synthesis and secretion, but its administration acts on physical growth also after hypophysectomy: zinc supplementation causes a significant increase in liver synthesis of IGF-I (somatomedin C), which, in chronic mineral nutritional deficiency, is remarkably reduced. In men, in this condition, GH response to its releasing factor (GRF) is normal: a demonstration of the less important role of the pituitary gland in this situation. Therefore, in chronic zinc deficiency, reduced liver production of IGF-I is responsible for reduced physical growth; moreover in this situation receptor resistance to IGF-I (in addition to GH), that fades away after dietetic supplementation of the mineral, has been demonstrated. Therefore zinc play an important role at receptor level, throughout various mechanisms (including a proven increase in receptor number, due to its aggregating membrane direct induced effect).
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Istituto di Clinica Medica Generale, Università degli Studi, Ferrara.
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D000818:Animals; D013006:Growth Hormone / Q000172:deficiency / Q000502:physiology*; D006801:Humans; D011986:Receptors, Somatotropin / Q000187:drug effects / Q000502:physiology; D013002:Somatomedins / Q000502:physiology; D015032:Zinc / Q000172:deficiency / Q000502:physiology*
D011986:Receptors, Somatotropin; D013002:Somatomedins; D013006:Growth Hormone; D015032:Zinc