Effects of ammonia and urea in vitro on mRNA of candidate bovine endometrial genes

Large amounts of protein intake are associated with elevated ammonia and urea concentrations in both plasma and uterine fluid in dairy cows. These increased concentrations affect successful embryo development and subsequent pregnancy establishment. The objective of the present study was to examine the effects of ammonia and urea on the expression of some candidate genes in the endometrium of mid-luteal phase of the estrous cycle of dairy cows. Endometrial explants were cultured and treated with 0, 75, 150, 300, 600 μM of ammonium chloride or 0, 4, 8, 12, 16 mM of urea. After the RNA extraction and reverse transcription, real time PCR was performed to assess the treatment effects on relative amounts of mRNA of candidate genes. BCL2 mRNA was greater in explants treated with 150 μM of ammonium chloride compared to explants treated with 0, 75 and 300 μM. Relative amounts of IGFBP1 mRNA were less in explants treated with 600 μM of ammonium chloride when compared with other concentrations. Relative FGF2 gene expression was less in explants treated with a greater concentration (600 μM) of ammonium chloride or urea (16 mM) when compared with lesser concentrations. Expression of HSPA1A, IGFBP3 and SERPINA14 genes was greater in explants exposed to lesser concentrations (150 μM) of ammonium chloride or urea (4 mM). Relative amounts of IGF1 and BAX mRNA were not affected by any of the ammonium chloride or urea concentrations tested. In conclusion, greater concentrations of ammonia and urea have negative effects on some endometrial gene expression, while moderate concentrations have positive effects.