Effects of low‐dose melamine exposure during pregnancy on maternal and fetal kidneys in rats

Abstract

Despite the previous reports on melamine contamination in high concentrations some years ago, there were not many studies on low-level exposure in daily life, particularly in pregnancy. We investigated the effect of low-dose melamine on the kidneys of the pregnant rats and their developing embryos/fetuses during various gestational stages namely implantation, gastrulation, organogenesis, maturation and whole pregnancy. Our results showed that the repeated low level of melamine (12.5, 25, and 50 mg/kg bw/d) during pregnancy did not cause obstruction of renal tubules although more precipitating crystals were found in the early gestational periods. Simple hyperplasia in the maternal tubules and pelvic epithelium were more prominent after exposed to melamine during the whole gestational period. Neonatal kidneys significantly suffered more from congestion in glomeruli and interstitium, dilated tubules and interstitial edema after melamine administration to the mother in the late and the whole gestational periods. A trend of advance of glomerular development in fetuses was also observed. We conclude that in utero exposure of low-level melamine could post a risk on the kidneys of the pregnant mother as well as the developing fetuses, which may further increase the possibility of other health problems later in life.

Melamine induced changes in histopathology of the main organs and transcriptional levels of MAPK signaling genes in kidneys of female mice

“…Previous studies confirmed that melamine can change the structure of the kidney and induce kidney disease 38,41 . It was indicated that melamine could induce renal toxicity in pregnant rats 42 . In this study, pathophysiological changes of kidney was also induced by melamine.…”

Continuing Occurrence of Melamine and Its Derivatives in Infant Formula and Dairy Products from the United States: Implications for Environmental Sources

“…Given that the nephrotoxic effects of melamine are mediated by uric acid, probably not cyanuric acid, its potential risk to human health may be low. However, recent epidemiological studies suggested that the pathogenic mechanisms are different between low chronic and acute exposure (e.g., 2008 Chinese melamine-tainted food scandal) of melamine , and that the low and continuous melamine exposure was linked to the risk of uric acid and calcium urolithiasis. − Furthermore, the TDI value reported above was derived from a short-term animal toxicity assay conducted 30 years ago . More stringent regulations on melamine in food are needed, especially considering the synergistic effects of melamine with other environmental chemicals, including cyanuric acid, , uric acid, and di­(2-ethylhexyl) phthalate .…”

Development of analytical method of melamine in placenta from pregnant women by isotope‐dilution liquid chromatography/tandem mass spectrometry

“…6,14,17,18 No human studies have attempted to examine the effect of maternal melamine exposure on kidney function or renal morphology in their fetuses; only animal studies have investigated this relationship. [21][22][23][24][25][26][27][28][29] Our use of isotope dilution liquid chromatography/tandem mass spectrometry (LC/MS/MS), which we plan to use in the second stage of our studies, has found melamine in the placenta of humans.…”

“…In mammals, mother and fetal compartments are separated by the placenta, an organ that connects the developing fetus to the uterine wall and the only source of nutrients from the pregnant mother . Animal studies, which have detected melamine in the placentas, amniotic fluid, and even fetus or neonatal kidney in rats, have concluded that melamine can cross the placental barrier and enter the fetus …”

“…20 Animal studies, which have detected melamine in the placentas, amniotic fluid, and even fetus or neonatal kidney in rats, have concluded that melamine can cross the placental barrier and enter the fetus. [21][22][23][24][25][26][27][28][29] There are several quantitative methods for measuring melamine in different biospecimens, including plasma and tissue (kidney, placenta, etc.) in in vivo studies.…”