| Cows have multiple pregnancy cycles throughout their lives.Mammary epithelial cells undergo the process of proliferation,differentiation and apoptosis in each cycle.The study of mammary epithelial cell proliferation is an important safeguard for improving milk production of cows.Some studies have shown that the supplement of eucommia ulmoides extract in feed can promote milk production of cows,but the effect of eucommia ulmoides extract on breast development has not been reported.In this study,mice at the age of 4 weeks were randomly divided into 3 groups: the high-dose group(5‰),the low-dose group(1‰)and the control group.The extracts of eucommia ulmoides were added to the diet of pregnant and lactating mice,and the weaned mice were fed with the same diet.H&E staining and real-time quantitative PCR(q-PCR)were used to study the effects of eucommia ulmoides extracts on the morphological structure and proliferation of mouse mammary glands.The results were as follows:1.During the pregnancy period,the mice were prefed for 2 weeks,the mammary gland H&E staining result of 17 days pregnant mice showed that the alveolar morphology was more obvious in the low-dose group and the high-dose group than the control group,and the guide wall was significantly thickened.q-PCR result showed that the expression levels of IGF-2 gene in both low-dose and high-dose groups were significantly upregulated(P < 0.001),.Cyclin D1 also showed the same trend,suggesting that eucommia ulmoides extract could promote breast development during pregnancy.By comparing the daily weight gain of each group,it was found that the daily weight gain from the high-dose group was significantly faster than that of the control group.H&E results showed that the mammary glands of the high-dose and low-dose groups presented more acinus and more obvious alveolar structure in the early stage of lactation compared with the control group.2.After weaning,the young mice were fed to the age of 6 weeks and 8 weeks.The results showed that the 6-week-old high-dose group and low-dose group developed an obvious terminal end bud(TEB)structure,and the duct extended faster than the control group.The mammary gland of 8-week-old high-dose group was approaching the state of sexual maturity,and the proliferation and development rate of the duct was significantly faster than that of the low-dose group and control group.The results of q-PCR showed that the expression level of ERα in 6-week-old mouse mammary gland was increased(P < 0.001),and the expression level of downstream gene AREG was also significantly increased(P < 0.01),indicating that eucommia ulmosus extract had a role in promoting cell proliferation in adolescence.3.Cow mammary epithelial cell line(BMECs)was selected for in vitro experiment,and cell proliferation was detected by Ed U method after 48 h of treatment with eucommia ulmoides extract.It was found that the proportion of proliferating cells increased with the supplement of eucommia ulmoides extract concentrations,and the number of cell proliferation in the 500 mg/m L group was significantly higher than that in the control group(P < 0.01).In general,through the preliminary study of breast proliferation during pregnancy and adolescence,this study found that eucommia ulmoides extract played an important role in the lactation process,which may be realized by regulating the proliferation of breast epithelial cells.The effect of eucommia ulmoides extract on the proliferation of mammary epithelial cells was further illustrated in vitro with BMCEs,which provided a theory basis for the application of eucommia ulmoides in livestock practice. |
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