Effects Of Copper On The Secretion Of SS From The Swine Hypothalamus

Two experiments were conducted to study the effects of copper on somatostain(SS/SST) of hypothalamus of piglets.1. Effects of copper on the concentration of SS in culturing nerve cells from the swine hypothalamus in vivoThe hypothalamuses were taken from the embryos of 3 Landrace sows at the pregnancy of 42,45,60 days and 4 Landrace new bom piglets. All nerve cells of the hypothalamus were divided into 4 groups at random. Copper was supplemented into culturing media at four levels (0, 7.8 umol/L, 15.6 umol/L and 31.2 umol/L, respectively) when they had been cultured after 10 days. The result indicated that the variation of the SS concentration among the four groups was not significant, after nerve cells being cultured for 12 hours.2. Experiment of weanling pigletsThe growth experiment was conducted to study the effect of dietary copper with various levels and sources on the performance of piglets, content of copper and GH (growth hormone) in serum, and SS in hypothalamus and metabolism of CA (catecholamine) in hypothalamus.75 weanling piglets were completely divided at random into 5 groups with 15 pigs in each group. 5mg/kg copper sulfate was supplemented to the control diets, the copper content of 4 experimental diets were 125mg/kg, 250mg/kg copper sulfate and copper methionine, respectively, provided, the level of dietary methionine was the same.The results showed that the average daily gain (ADG) and average daily feed intake (ADF) of experimental groups were significantly higher than those of control group (p<0.05).Comparing with the control group, the contents of copper & GH in serum in 4 experimental groups increased significantly (p<0.05) , and there was a positive correlation between the levels of dietary copper and the contents of copper in serum including GH in serum (r=0.8191,n=15,p<0.01) .The concentration of SS in control group was the highest among all groups. The concentrations of SS in diets contenting copper sulfate were significantly higher than that of copper methionine, when supplemented with equal level of copper(125mg/kg or 250mg/kg).There was a negative correlation between the serum copper content and the SSconcentration (r=-0.6119, n=l 5, p<0.05) , and between the serum GH content and the SS concentration (r=-0.3747, n=15,p<0.05) .Comparing with control group,the concentrations of DA(dopamine) & NE(noradrenalin) increased significantly (p<0.05) . Supplemented with equal level(125mg/kg or 250mg/kg) of copper, the concentrations of DA in copper sulfate groups were significantly lower than that in copper methionine groups (p<0.05) .Comparing with control group, activity of MAO (monoamine oxidase) in the groups supplemented with 125mg/kg copper methionine decreased significantly (p<0.05 ) . Supplemented with 125mg/kg copper, activity of MAO (monoamine oxidase) in copper sulfate was higher than that of copper methionine.There was a negative correlation between the concentration of SS and the concentrations of DA & NE(r=-0.8895, n=15, P<0.01;r=-0.5403, n=15, p<0.05), between the activity of MAO and the concentration of DA (r=-0.7563, n=15, p<0.05 ) , when diets were supplemented with high level copper(125mg/kg or 250mg/kg).The results showed that sulfate copper did not directly restrain the secretion of SS from the swine hypothalamus in vivo.The diet of high copper level stimulated significantly the secretions of DA and NE, but at the same time it restrained the secretion of SS from the swine hypothalamus. The significant difference between DA and SS may be caused by the difference between copper methionine and copper sulfate in regulating MAO of hypothalamus.