The Reproductive Toxicity Of Melamine In The Absence And Presence Of Cyanuric Acid In Mice

"China Sanlu milk power incidenf" has been drawn widespread attention for melamine at home and abroad. The study about the toxic of melamine is also more and more,but more about the toxic effects of melamine alone.The results showed that the melamine is a low-toxic substances. Recently, the study about the toxic effects of melamine and cyanuric acid mixture showed that the toxic of melamine and cyanuric acid mixture is more than melamine alone. Currently, the study about the toxic effects of melamine and cyanuric acid mixture are mainly focused on the toxic effects of melamine and cyanuric acid mixture to the kidney and liver. Few reports about the toxic effects of these compounds on the reproductive system.The experimental are mainly about the study of melamine alone and melamine and cyanuric acid mixture to the toxic effects of the reproductive system in mice, in order to supplement the toxicological data for melamine.Test one The reproductive toxicity of melamine in the absence and presence of cyanuric acid in male miceMethod:56male mice weighing25-30g were randomly selected and divided into seven groups. The mice of control group were administered1mL of physiological saline. The mice of melamine group were administered with melamine alone, at doses of2(low dose),10(middle dose),and50(high dose) mg/kg/day. The mice of mixed groups were administered with the combination of melamine and cyanuric acid at the dosages consisting of1(low dose),5(middle dose), and25(highdose) mg/kg/day of each. All administrations were made via gastric gavages for30consecutive days. At the end of the experiment, all mice of each group were sacrificed by cervical dislocation, and the testis tissues were collected immediately from each mouse to histopathological examination,electron microscopy, apoptosis detection and immunohistochemistry.Results:①Clinical observations,no abnormal reaction in the melamine groups with low, middle doses and control group.However,compared with the control group,the co-administration group of melamine and cyanuric acid and melamine with high dose had exhibited anorexia, dull and depression. In particular, mixed high dose group hair dull, slow-growing.②Testicular histopathology examination,spermatogenic cells of the mouse from control group at all stages exhibited normal development including spermatogonia, primary spermatocytes, secondary spermatocytes, and sperm cells.However,Compared with the control group, spermatogenic cells at all stages of other experimental groups of mice with different degrees of changes.Melamine group with high dose,co-administration of melamine and cyanuric acid groups with middle and high doses are most serious.With decreased layers of epithelial cell and the structural damage was found in many spermatogenic cells at all stages. Also, swelling and lysis of nucleus occurs in the primary spermatocytes, secondary spermatocytes and the sperm cells with the uneven size and staining of varying intensity.In addition, a reduction in the number of sperm or even no mature sperm was observed in some sertoli cells of seminiferous tubule.③Ultrastructural changes of testicular tissue in mouse, the morphological structure had a different degrees of changes was observed in the leydig cells and seminiferous cells at all stages of the mice from middle and high doses groups of melamine.Irregular nucleus shapes were observed in interstitial cells of mixed doses groups with margical collection of heterochromatins in a few cell nuclei.In addition, the mice from co-administration groups of melamine and cyanuric acid with middle and high doses exhibited some indistinct of nuclear membrane, and lysis of cytoplasm in spermatogonia and primary spermatocytes.Compared with mixed group with low and middle does,Co-administration of melamine and cyanuric acid with high dose is more obvious.④Apoptosis examination of spermatogenic cells,compared with control group, the animals treated with high dose of melamine alone,co-administration group of melamine and cyanuric acid with middle dose had a significant increase in apoptotic index of spermatogenic cells (P <0.05).Compared with control group, co-administration group of melamine and cyanuric acid with high dose had a significant increase in apoptotic index of spermatogenic cells (P<0.01).⑤Iinmunohistoehemistry results showed that the animals treated with melamine alone and co-administration group of melamine and cyanuric acid,the expression of Bax protein was both increased. The animals treated with high dose of melamine had a significant increase (P<0.05).Co-administration of melamine and cyanuric acid with middle and high does had a significant increase (P<0.01).Animals treated with melamine alone and co-administration group of melamine and cyanuric acid,the expression of Bc1-2protein was both declined.Compared with control group, the animals treated with high dose of melamine had a significant decreased (P<0.01).Co-administration of melamine and cyanuric acid with middle does had a significant decreased (P<0.05).Co-administration of melamine and cyanuric acid with high does had a significant decreased (P<0.01)Test two The reproductive toxicity of melamine in the absence and presence of cyanuric acid in female miceMethod:56female mice weighing25-30g were randomly selected and divided into seven groups including one control group, three melamine groups (low, middle, andhigh doses), and three mixed groups of melamine and cyanuric acid (low, middle, and high doses). The mice of control group were administered1mL of physiological saline. The mice of melamine group were administered with melamine alone, at doses of2(low dose),10(middle dose),and50(high dose) mg/kg/day. The mice of Mix groups were administered with the combination of melamine and cyanuric acid at the dosages consisting of1(low dose),5(middle dose), and25(highdose) mg/kg/day of each. All administrations were made via gastric gavages for30consecutive days. After30days, all mice of each group were sacrificed by cervical dislocation, blood and the ovarian tissues were collected immediately from each mouse, to detect progesterone,estradiol and detect the expression of ER and PR gene in the ovary.Result:①The progesterone and estradiol levels are decreased in groups of melamine alone in mouse serum.But progesterone did not show significant difference (P>0.05),estradiol levels had a significant decreased in melamine groups with middle and high doses (P<0.01).Co-administration of melamine and cyanuric acid, progesterone levels had a significant decreased (P<0.01), estradiol levels had a significant decreased in mixed groups with middle and high doses.②RT-PCR results showed that compared with control group, the expression of ER gene did not show significant difference in melamine group with middle dose (P>0.05).Mixed group with low does and melamine group with high dose,signifieant differenee (P<0.05), mixed groups with middle and high doses, signifieant difference (P <0.01).The expression of PR gene had decreased in melamine group and mixed group. Compared with control group, melamine group with low and middle doses and mixed groups with low dose did not show significant difference.Howere,mixed group with low and middle doses and melamine group with high dose,signifieant difference (P<0.01)...