Animal Model Establishment And Its Mechanism Of N-carbamoylglutamate’s Effect On Sexual Development

In large-scale farms, delayed puberty, out of heat and even breeding failure of gilts are occurred frequently. Two experiments were desigened to evaluate the effect of diet supplemented with N-carbamoylglutamate（NCG） on sexual development and its mechanism in SD rats.Experiment 1: The aim of this experiment is to exvulate the effect of NCG on sexual development in polytocous animals. Totally 60 SPF SD female rats were selected and divided into control group, 0.05% NCG group and 0.1% NCG group randomly. The rats of tested groups（0.05% NCG and 0.1% NCG） fed on based diet supplemented with diffenent levels of NCG, the control group fed on based diet only. Female SD rats were mated after 65-day-old（before puberty） through putting male rats into their cages. The puberty of tested rats were detected by vaginal plug after mating. The number of litter alive were recorded both at farrowing and weaning（21 days） in the first and second parities. Compared with the control group, female SD rats supplemented with NCG can reach their puberty by 3.5 d to 4.2 d（P<0.05） ahead. The number of litter born and born alive showed insignificant difference（P>0.05）, while NCG adminstration can increase the number of rat alive by 2.0-2.8 at weaning（P<0.05）. In their second parities, no negative effect was found on the number of born and born alive, as well as birth weight（all P>0.05） in NCG adminstration. In summary, diet administration with NCG can reach puberty more earlier and increase the number of rat alive at weaning, which can improve sexual development and obtain truely precocious puberty in female SD rats.Experiment 2: According to the results of NCG improving sexual development in polytocous animals, Gn RH cell models in vitro--GT1-7 neuronal cells were used to investigate the effect of 17β-estradio（E₂） on the secretion of Gn RH, as well as the expression of genes（ER, KISS-1, GPR54 and Gn RH） related with pubery onset. GT1-7 cells of tested groups were treated with E₂ in different concentrations（10-11-10-5 M） and different time（6-30 h）, while the control group was treated with the solvent（ethanol） only. Gn RH concentration of supernatants were determined by enzymelinked immunoassay（ELISA） and genes expression were determined by relative fluorescence quantitative method. The results showed that GT1-7 cells treated with E₂ have an effect on both Gn RH secretion and Gn RH, ERα, KISS-1 and GPR54 m RNA expression. When cultured with 100 p M E₂ for 12 h, the level of Gn RH secretion and Gn RH, ERα, KISS-1 and GPR54 m RNA expression were significantly increase in GT1-7 cells, while cultured with 1 μM E₂ for 24 h presented an opposite function. The conclusion of this experment were GT1-7 cells treated with 100 p M E₂ for 12 h presented a positive regulation cell model in vitro and 1 μM E₂ for 24 h did a negative one, which could provide a theoretical foundation for further research on sexual development and puberty onset in animals.