The Moleculer Mechanism Of Copper-stimulated Growth

Abstract:The present study was conducted to evaluate the effect of different copper levels on the growth of weanling pigs and on the proliferation of cartilage cells in vivo. In the first experiment, 60 of weanling pigs were randomly assigned into six groups of 10 each, fed on basal diets supplemented with 0,100,150,200,250,300mg/kg copper for 80 days, respectively. The average daily gain (AGD), gain:feed (GF), copper concentration, activities of copper protein(or ceruloplasmin,CP) and superoxide dismutase (SOD), growth hormone (GH), insulin-like growth factor I (IGF-l)and insulin-like growth factor binding protein 3 (IGFBP3) levels in serum were detected at interval of 20 days. in the second experiment, cartilage cells from the lateral trochler ridge of the distal femur in one-day pig were cultured in medium supplemented with 0,7.8,15.6,31.2,62.5 i~ mol/L copper. IGF- I and IGFBP3 levels in culture medium were determined with radioimmunoassay (RIA). DNA synthesis in chondrocytes was measured by 3H-thymindine incorporation. The results were as follows: ADG, CP and SOD activities,copper concentration,GH,IGF-I and IGFBP3 levels in serum were increased significantly in the pigs fed on diets added with l00,150,200,250,300mg/kgCu. From 20th to 60th day of the experiment, ADG had a significantly positive correlation with copper levels in diets, copper levels in serum, activities of CP and SOD in serum, and levels of GH,IGF-1 and IGFBP in55serum, respectively. Meanwhile, levels of GH.,IGF-1 and IGFBP in serum had a significant positive correlation with copper in diets, copper levels in serum, activities of CP and SOD in serum from 20th to 40th day of the experiment. Proliferation-promoting activity and incorporation of 3H-thymindine in chondrocytes increased in culture medium added with 7.8,15.6 and 31.2 i~ mol/L Cu. The content of IGF- I and IGFBP3 in chondrocytes was also enhanced significantly in culture medium with 15.6,3 1.2,62.5 i.t mol/L Cu. The results showed that effects of copper supplemented in diets and in culture medium on growth in pigs and chondrocyte proliferation were related to the increasing levels of GH, JGF-1 and IGFBP3 in serum or culture medium which were induced by copper.