Laboratory of Genetic Improvement and Healthy Breeding of Dairy Goats, Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China.
Department of Animal Science, University of California, Davis, CA 95616, USA.
J Anim Sci. 2022 Mar 1;100(3). doi: 10.1093/jas/skac065.
Due to the large amounts of calcium transferred to milk from mammary glands, periparturient dairy goats face challenges with calcium metabolism disorder and hypocalcemia. Serotonin (5-hydroxytryptamine, 5-HT), the product of 5-hydroxy-l-tryptophan (5-HTP) catalyzed by tryptophan hydroxylase 1, is a multifunctional monoamine thought to be a homeostatic regulator of the animal. The objective of the current study was to investigate the effects and underlying mechanisms of intramuscular 5-HTP injections on calcium homeostasis in the goat mammary glands. In the in vivo experiment, 30 multiparous Guanzhong dairy goats were randomly assigned to 2 groups, one group was injected with 5-HTP intramuscularly and the other group was injected with normal saline. From the first 10 d of the expected date for delivery, 5-HTP or saline was injected into goats through the shoulder muscle every morning before feeding, with a dose of 1 mg/kg per body weight. In the in vitro experiment, goat mammary epithelial cells (GMEC) were treated with 100 μM 5-HT for the evaluation of 5-HT in calcium transportation. The results demonstrated that 5-HTP treatment had no effect on the basic composition of colostrum (P > 0.05) but increased the serum 5-HT concentrations on days -5, -4, -3, and 5 relative to parturition (P < 0.05). The 5-HTP injection group had greater serum calcium concentration on day 4 and greater serum parathyroid hormone-related protein (PTHrP) on days -5, -4, -1, 3, 4, and 5 compared with the saline injection group (P < 0.05). It was further confirmed that 5-HT could increase intracellular calcium levels by increasing PTHrP and decreasing plasma membrane Ca2+-ATPases1 (PMCA1) in GMEC (P < 0.05). In conclusion, 5-HTP treatment in multiparous goats during the transition period from pregnancy to lactation is a feasible way to protect goats from calcium metabolism disorder.
由于乳腺向牛奶中转移了大量的钙，围产期奶山羊面临钙代谢紊乱和低钙血症的挑战。血清素（5-羟色胺，5-HT）是色氨酸羟化酶 1 催化 5-羟色氨酸（5-HTP）产生的一种多功能单胺，被认为是动物体内平衡的调节剂。本研究旨在探讨肌肉内注射 5-HTP 对山羊乳腺钙稳态的影响及其潜在机制。在体内实验中，将 30 只经产关中奶山羊随机分为 2 组，一组肌肉内注射 5-HTP，另一组注射生理盐水。从预计分娩前 10d 开始，每天早上在喂奶前通过肩部肌肉向山羊注射 5-HTP 或生理盐水，剂量为 1mg/kg 体重。在体外实验中，用 100μM 5-HT 处理山羊乳腺上皮细胞（GMEC），以评估 5-HT 在钙转运中的作用。结果表明，5-HTP 处理对初乳的基本成分没有影响（P>0.05），但与分娩相比，血清 5-HT 浓度在-5、-4、-3 和 5d 时升高（P<0.05）。与生理盐水注射组相比，5-HTP 注射组在第 4 天血清钙浓度较高，在-5、-4、-1、3、4 和 5d 时血清甲状旁腺激素相关蛋白（PTHrP）浓度较高（P<0.05）。进一步证实，5-HT 可通过增加 PTHrP 和减少 GMEC 中的质膜 Ca2+-ATPases1（PMCA1）来增加细胞内钙水平（P<0.05）。综上所述，围产期奶山羊在妊娠向泌乳过渡期肌肉内注射 5-HTP 是一种保护其免受钙代谢紊乱的可行方法。
