文献类型： 外文期刊

作者： Du, Wei ¹ ; Zhang, Zhi Fei ¹ ; Xiao, Jia Ying ¹ ; Wang, Ying ¹ ; Liu, Weng Yi ¹ ; Zheng, Hui Ling ¹ ;

作者机构： 1.Northwest A&F Univ, Coll Anim Sci & Technol, Shaanxi Key Lab Mol Biol Agr, Yangling, Shaanxi, Peoples R China

2.Guangdong Acad Agr Sci, Inst Anim Sci, Guangzhou, Peoples R China

关键词： 5-HTP; beta-casein; JAK2; STAT5a; apoptosis; mammary epithelial cell

期刊名称：JOURNAL OF ANIMAL SCIENCE （ 影响因子：3.3； 五年影响因子：3.1 ）

ISSN： 0021-8812

年卷期： 2023 年 101 卷

页码：

收录情况： SCI

摘要： 5-Hydroxytryptamine (5-HT) is an amine produced in both the mammary gland and the central nervous system. Tryptophan hydroxylase 1 (TPH1) catalyzes the conversion of 5-hydroxytryptophan (5-HTP) into l-tryptophan, which is then converted into 5-HT by monoamine-oxidase (MAO-A). In the mammary gland, 5-HT has been shown to have a variety of paracrine-autocrine actions, including suppressing lactation, controlling the destiny of mammary epithelial cells, and maintaining calcium homeostasis throughout the transition from pregnancy to lactation. To examine the effects of 5-HT on the composition of colostrum and milk, a total of 30 transition Guan Zhong dairy goats were intramuscularly injected with 5-HTP (1.0 mg/kg) every morning before feeding from 10 d before the projected parturition date to the day of parturition. The average number of days animals received injections was 8.2 3.2 d. 5-HTP treatment increased serum 5-HT concentration from days 5 to 2 relative to parturition (P < 0.05), and decreased the casein concentration of colostrum (P < 0.05). In the in vitro experiment, mammary epithelial cells isolated from three individual goats' mammary glands were separately treated with 200 mu M 5-HTP, 30 mu M PCPA (the specific inhibitor of TPH1), or 200 mu M 5-HTP + 50 mu M SB269970 (the selective antagonist of 5-HTR7). The results showed that 200 mu M 5-HTP inhibited the expression of beta-casein, downregulated the activity of the JAK2/ STAT5a signaling pathway, and promoted the apoptosis of goat mammary epithelial cells (GMECs) (P < 0.05). When GMECs were treated with 30 mu M Four-chloro-dl-phenylalanine (PCPA), a specific inhibitor of 5-HT synthesis, the mRNA expression of STAT5a and the phosphorylated STAT5a protein level were upregulated. The 50 mu M SB269970 treatment rescued the effects of 5-HTP on GMECs (P < 0.05). Taken together, the results indicated that 5-HTP exerted an inhibitory effect on beta-casein synthesis and a proapoptotic effect in GMECs via HTR7 and the JAK2/STAT5a axis. Discover the surprising role of 5-hydroxytryptamine (5-HT, serotonin) in inhibiting the synthesis of milk protein in mammary glands, as well as its potential as a molecular target for rescuing this effect. This study identifies HTR7 as the key player in rescuing the inhibitory effect of 5-HT on casein synthesis in goat mammary epithelial cells. Lay Summary 5-Hydroxytryptamine (5-HT), which is produced in both the mammary gland and the central nervous system, is a recognized important regulator of mammary gland homeostasis. Casein is the major protein in the milk of mammals including cows, goats, and humans, and is a crucial source of high-quality amino acids for humans. In this study, prenatal intramuscular injection of 5-hydroxytryptophan (5-HTP), the precursor of 5-HT, not only increased the level of 5-HT in the serum of goats before delivery but also decreased the concentration of casein in colostrum. Furthermore, in goat mammary epithelial cells which are responsible for milk synthesis, it was found that 5-HTP blocked genes and signal pathways related to casein synthesis, and also promoted cell apoptosis. Additional results demonstrated that the type 7 5-HT receptor (HTR7) mediated the impacts of 5-HT, which provided a potential reliable target for improving milk quality.