| Since Braude found that large amount of copper as additive added into diets had specific stimulating growth for growing pigs in 1945, copper as additive has been used universally and many experiments have been conducted about it. It is well known that copper as sulfate pentahydrate added into diets from 100 mg/kg to 250mg/kg stimulated the growing performance in early growing stage of pigs (especially the pig weight below 50kg), but the function of growing performance of copper was gradually lessened in latter stages. According to the effect of adding a suitable dosage copper sulfate pentahydrate in pig diets upon feed intake, enzyme activity and stimulation of hormone related to growth regulation, the mechanism on the stimulating growth of high dosage copper was likely related to improving food intake, enhancing enzyme activity and stimulating some relative hormone of growth regulation. Therefore, the regulation of neuroendocrine must be learned much to explore the mechanism of stimulating animal growth of copper.It was investigated that animal growth was regulated by the axis of growth, the protocol of GH and IGF-1 being its center. What's more, the secretion of GH and IGF-1 was improved because of copper addition, and the contents of some hormone secretion related to the GH releasing in hypothalamus was regulated by large amount of copper, such as SS, GHRH and Ghrelin, etc.DA (dopamine) is an important neurotransmitter of central nervous system, it belongs to CA (catecholamine). It was proved that its active form was L-Dopa, which had a striking function of accelerating animal growing, and copper was functioned as enzyme form and participated in CA metabolism. So the effect of the copper on the DA metabolism of central nervous system and some hormones related to the GH releasing of the growth axis was studied in this experiment. It was of great importance to explain the mechanism of stimulating animal growth of copper.The experiment of two copper sources and three supplemented treatments (5 mg/kg, 125 mg/kg, 250mg/kg) was conducted, which was lasted for 45 days, in which seventy-five piglets were randomly assigned to five groups of fifteen pigs (each setting up five repetitions). The findings were tested by molecular cloning, immunohischemical and radio-immunity technique, etc. This experiment of growth was conducted to study the effect of large amount of copper on DA metabolism in swine mesencephalic nigra, hypothalamus and stratal tract.The result was as follows: The metabolism contents of DA in swine mesencephalic nigra were prominently enhanced due to high dosage copper supplemented in diets, and the concentrations of DA in hypothalamus were significantly promoted, too. What's more, the releasing contents of SS were significantly decreased. But there was no obvious regulation of the data of the metabolism contents of DA in swine stratal tract.In experimented groups, the metabolism contents of DA in swine mesencephalic nigra were prominently improved by the high dosage copper added into the diets, there was no significant difference in two copper sources, but with promoting Cu supplemented concentrations, the levels of DA in mesencephalic nigra tended to decline. The NA(noradrenaline) contents in swine mesencephalic nigra among the groups supplemented with 125mg/kg (p<0.05) > 250mg/kg (p<0.01) Cu as copper sulfate pentahydrate compared with the controlled group were significantly different. What's more, with promoting Cu supplemented concentrations, the concentrations of NA tended to rise; the concentrations of NA in the group of 125mg/kg (p<0.01) Cu as copper methionine were much higher than those of the controlled group, but there was no striking difference between the concentrations of NA in the group of 25Omg/kg (p<0.01) Cu as copper methionine and the controlled group. The concentrations of Cu in serum had a positive relation with the concentrations of DA and NA in mesencephalic nigra(r=0.7338,n=15,P<0.05; r=0.6383,n=15,p<0.05).The DA levels of all experimented groups in swine hypothalamus had prominently a more increase because of high amount copper supplement than those of the controlled group. In addition, the DA levels in the two groups supplemented with Cu as copper methionine were significantly higher than those of Cu as copper sulfate pentahydrate (p<0.05); compared with the controlled group, the NA levels in swine hypothalamus had a significant rise because of high dosage copper supplement (p<0.01) ,when promoted Cu supplementing concentrations from 125 mg/kg to 250 mg/kg in the pig diets, the levels of DA and NA all had a declining tendency, the NA levels in the groups supplemented with Cu as copper sulfate pentahydrate was significantly higher than those of the groups supplemented with Cu as copper methionine (p<0.05). The concentrations of DA in swine mesencephalic nigra had a positive relation with the contents of NA in swine hypothalamus (r=0.9585, n=15, p<0.01) . SS secretion in swine hypothalamus was prominently restrained due to high dosage copper supplement.The activity of DP H in groups supplemented with 125mg/kg(p<0.05) > 250mg/kg(p<0.05) Cu as copper sutfate pentahydrate was significantly higher than those in groups supplemented with 125mg/kg(p<0.05)> 250mg/kg(p<0.05) Cu as copper methionine. The activity of MAO-B in groups supplemented with 125mg/kg(p<0.01), 250mg/kg(p<0.01) Cu as copper sutfate pentahydrate was significantly higher than those in groups supplemented with 125mg/kg(p<0.01)> 250mg/kg(p<0.01) Cu as copper methionine . In summary, relative enzyme activity of copper in swine mesencephalic nigra and hypothalamus were significantly enhanced, and the metabolism of DA in swine center nervous system were improved as well.Therefore, on the regulation of stimulating animal growth of high dosage copper, the metabolism of DA, NA and etc. in swine center nervous system were increased by relative enzyme activity of copper improved because of large amount of copper, as a result, some kinds of hormone secretion in the growth axis finally being regulated, and then stimulated the pig growth.
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