Effects Of Melamine On Genitourinary System And Placental Functions In Pregnant Rats

Objective By establishing pregnant rats'pregnancy melamine poisonous model, researchmelamine to pregnant rats'kidney and ovarian pathological changes of the organizations and thehormone levels and placenta influence, explore melamine to pregnant rats genitourinary systemand placental functioning.Methods 40 Wistar pregnant rats were randomly divided into control group (n=10, the ratswere given equal amount of vegetable oil) and melamine experimental group (n=30, the ratswere given 400mg/kg, 800mg/kg and 1200mg/kg of melamine-mixed vegetable oil respectivelyin each subgroups), the rats were mated in ratio of male: female=2:1. From the 6th to the 19thdays of pregnancy, the rats in the control group were continuously fed with vegetable oil andthose rats in the melamine experimental group were continuously fed with 400mg/kg, 800mg/kgand 1200mg/kg of melamine respectively. The changes in body weight and abnormal symptomsof the pregnant rats in the two groups were observed. At the 20th days of gestation, the pregnantrats were sacrificed and the organ co-efficient (organ relative weights) of heart, liver, kidneys,spleen, lung, bladder, uterus and ovary, and the number of ovarian corpus luteum werecalculated. The pathological changes tissues of ovarian, kidney, liver and bladder of the deadpregnant rats were observed. The serum levels of progesterone (P), placental lactogen (HPL) andestriol (E3) were detected by using radioimmunoassay method.Results (1)The pregnant rats in middle-dose melamine subgroup, low-dose melaminesubgroup and control group are in good condition, especially in eating, drinking and growth,obvious poisoning symptoms and signs were not observed . The rats in the high-dose melaminesubgroup presented with different degrees of poisoning symptoms in urinary and reproductivesystems. In the 9th and 11th days of gestation, two pregnant rats died. Autopsy found that thesizes of both kidneys, swelling, sallow color, surface uneven, hard, matte when longitudinal.(2) High-dose melamine subgroup and middle-dose melamine subgroup in the body weight ofpregnant rats compared with the control group were significantly decreased (P <0.01), low-dosemelamine subgroup and the control group (P = 0.725) there was no significant difference. Withthe dose increased, weight decreased.(3) With the increase in dose of melamine, the weight of pregnant rats in ovaries, liver, kidneyhad increased, uterine weight has been reduced. Groups'organ coefficient of pregnant rats inspleen, lung, bladder, heart did not change significantly. Groups organ coefficient of pregnant rats :â‘ the liver: high-dose melamine subgroup,and control group had significant differences (all P <0.001), low-dose melamine subgroup andcontrol group were significantly different (P <0.01);â‘¡kidney: the high, middle and low-dosemelamine subgroup and control group were significantly different respectively (all P <0.001);â‘¢ovaries: the high-dose melamine subgroup and control group were significantly different (P<0.01);â‘£uterus: the high-dose melamine subgroup compared with the control group there wassignificant difference (P <0.05).(4) High-dose melamine subgroup and middle-dose melamine subgroup in the number ofcorpus luteum compared with the control group significantly (all P <0.001), low-dose melaminesubgroup compared with the control group there was significant difference (P <0.01).(5) High-dose melamine subgroup of renal tubules tubal lumen expand, cavity visible stones,PAS stain see renal tubular mesangium matrix widened, epithelial empty bubble deformation,brush off disappear, transparent pipe flanges type, renal interstitial have lymphocytic infiltrates,fibrosis, partial glomerular glass sample degeneration. middle-dose melamine subgroup of renaltubular cavity and interstitial are visible granular crystallization, renal tubular brushed off theborder, visible minority lymphocytes. Glomerular cysts lined decrescent, full of homogeneousred dye substance.High-dose melamine subgroup of ovarian tissue found in vacuolar degeneration of luteumcells increase, decrease levels of follicle, atretic follicles were increased, showing that ovarianstones. middle-dose melamine subgroup of ovarian tissue found the luteum cells of ovariantissue can be seen between the crystalline particles.High-dose melamine subgroup: liver cell swelling, hypertrophy.High-dose melamine subgroup had mild bladder transitional cell loss, infiltration of laminapropria lymphocytes, did not see significant stones or crystals.(6)â‘ The serum levels of placental lactogen in the experimental groups are lower than thecontrol group, high, middle-dose melamine subgroup and control group had significantdifferences (all P <0.001), low-dose melamine subgroup and the control group there wassignificant difference (P <0.05)â‘¡The serum levels of progesterone in the experimental groupcompared with the control group there were significant differences (all P <0.001).â‘¢The serumlevels of estriol analysis of variance, F = 0.526, P = 0.669, no significant difference. The serumlevels of estriol were lower than the control group.Conclusion1 pregnancy pregnant rats exposed to high levels of melamine can cause obvious symptomsof the genitourinary system and even death.2 The exposure to high levels of melamine could induce lithiasis or crystal formation in kidney and ovary of Wistar pregnant rats, which may result in tissues of varying degrees injury.3 Each doses of melamine can reduce secretion of placental hormones, which are potentiallyharmful to placental function and the off-springs.