中文摘要：

[目的]本文旨在研究三聚氰胺与三聚氰酸混合物对小鼠睾酮生成和合成调控的影响。[方法]选40只4周龄雄性ICR小鼠随机分成4组,每组10只,分为三聚氰胺（MA）与三聚氰酸（CA）混合物（MC）低剂量组（MA、CA各1 mg·kg^-1,MC2）、中剂量组（MA、CA各5 mg·kg^-1,MC10）、高剂量组（MA、CA各25 mg·kg^-1,MC50）和对照组（玉米油灌胃）,连续灌服28 d;放射免疫法测定血清中睾酮含量,荧光定量PCR和蛋白免疫印迹法分别检测与睾酮合成相关的蛋白（St AR、P450scc、P450 17α和17β-HSD）及其基因的表达变化,免疫组织化学方法检测睾丸间质细胞数量。[结果]MC10和MC50组小鼠血清中睾酮含量显著低于对照组（P〈0.05）;与对照组相比,混合物处理各组的St AR mRNA和17β-HSD mRNA表达量明显下调（P〈0.05）,MC10和MC50组的P450 17αmRNA表达量以及MC50组的P450scc mRNA表达量也明显降低（P〈0.05）;睾酮合成相关的蛋白表达与mRNA水平变化一致,混合物处理各组的17β-HSD蛋白表达明显低于对照组,MC50组的P45017α蛋白表达以及MC10和MC50组的St AR及P450scc蛋白表达也明显低于对照组（P〈0.05）;MC50和MC10组的小鼠睾丸间质细胞数量极显著低于对照组（P〈0.01）。[结论]三聚氰胺与三聚氰酸混合物减少了间质细胞的数量并下调了睾酮合成相关蛋白的表达,导致血清中睾酮水平降低。

英文摘要：

[Objectives] The purpose of the present study was to examine the production and synthesis regulation of testosterone in mice after treating with mixture of melamine and cyanuric acid （MC）.[Methods] Forty male ICR mice were randomly separated into four groups and then were given 0,2（MC2）,10（MC10）or 50（MC50） mg·kg^-1·d^-1 melamine plus the same amount of cyanuric acid by oral gavage for 28 d. Serum levels of testosterone were detected by radioimmunoassay method,the mRNA expressions of genes associated with testosterone synthesis were detected by quantity real-time PCR（qRT-PCR）,the proteins associated with testosterone synthesis were detected by Western blot and the number of Leydig cells was detected by immunohistochemistry.[Results] The serum level of testosterone was significantly decreased in MC10 and MC50（P〈0.05）. Compared with the control group,mRNA transcription levels of StAR and 17β-HSD decreased significantly in treated groups（P〈0.05）,and the level of P450 17α in MC10 and MC50 decreased significantly（P〈0.05）. In addition,the mRNA level of P450scc decreased significantly in MC50. The protein expression of 17β-HSD in MC treated groups and P450 17α in MC50,and StAR and P450scc in MC10 and MC50 decreased significantly（P〈0.05）. The proteins expressions of StAR,P450scc,P450 17α and 17β-HSD had the same decreased trend with their mRNA transcription levels. StAR in MC10 and MC50,P450 17α in MC 50,P450scc in MC10 and MC50 and 17β-HSD in MC treated groups decreased compared with control group （P〈0.05）. The numbers of Leydig cells in MC10 and MC50 were also dramatically reduced （P〈0.01）.[Conclusions] The mixture of melamine and cyanuric acid down-regulated the expression of genes and proteins associated with testosterone synthesis and reduced the number of Leydig cells,and both of them contributed to the decrease of testosterone in sera.