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Liu Y, Li H. L-leucine promotes the synthesis of milk protein and milk fat in bovine mammary epithelial cells through the AKT/mTOR signaling pathway under hypoxic conditions. J Nutr Biochem 2024; 134:109732. [PMID: 39117078 DOI: 10.1016/j.jnutbio.2024.109732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 07/31/2024] [Accepted: 08/04/2024] [Indexed: 08/10/2024]
Abstract
Hypoxia stress has been demonstrated to impede animal embryonic development, spermatogenesis, and lactation, leading to decreased animal production performance. However, the impact of hypoxia-induced activation of hypoxia inducible factor-1 (HIF-1) signaling on milk protein and fat synthesis remains unclear. L-leucine, a branched-chain amino acid, is known to modulate milk protein and fat synthesis. Therefore, our study aimed to evaluate the effect of L-leucine on milk protein and fat synthesis under hypoxic conditions and shed light on the molecular mechanism using an in vitro model. The results indicated that hypoxia treatment significantly decreased the synthesis of α-casein and β-casein, as well as inhibited factors related to milk fat synthesis in bovine mammary epithelial cells (MAC-T). Additionally, hypoxia stress suppressed the activities of the mammalian target of rapamycin (mTOR) and protein kinase B (AKT). Interfering with HIF-1α significantly reversed the expression of AKT, mTOR and factors related to milk synthesis. Importantly, supplementation with L-leucine activated AKT/mTOR signaling, thereby enhancing milk protein and fat synthesis in MAC-T cells to some extent. In conclusion, these findings suggest that HIF-1 signaling plays an important role in milk synthesis and that L-leucine may stimulate the synthesis of milk protein and fat by activating the AKT/mTOR signaling pathway under hypoxic conditions, making it a potential additive for promoting milk synthesis inhibited by hypoxia.
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Affiliation(s)
- Yuan Liu
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Huixia Li
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China.
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Zhang J, Geng S, Zhu Y, Li L, Zhao L, Ma Q, Huang S. Effects of dietary methionine supplementation on the growth performance, immune responses, antioxidant capacity, and subsequent development of layer chicks. Poult Sci 2024; 103:103382. [PMID: 38176373 PMCID: PMC10792981 DOI: 10.1016/j.psj.2023.103382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 12/09/2023] [Accepted: 12/12/2023] [Indexed: 01/06/2024] Open
Abstract
Deficiencies or excesses of dietary amino acids, and especially of methionine (Met), in laying hens can lead to abnormal protein anabolism and oxidative stress, which affect methylation and cause cellular dysfunction. This study investigated the effects of dietary methionine (Met) levels on growth performance, metabolism, immune response, antioxidant capacity, and the subsequent development of laying hens. A total of 384 healthy 1-day-old Hyline Grey chicks of similar body weight were randomly allocated to be fed diets containing 0.31%, 0.38%, 0.43% (control group), or 0.54% Met for 6 wk, with 6 replicates of 16 chicks in each. The growth performance of the chicks was then followed until 20 wk old. The results showed dietary supplementation with 0.43% or 0.54% Met significantly increased their mean daily body weight gain, final weight, and Met intake. However, the feed:gain (F/G) decreased linearly with increasing Met supplementation, from 0.31 to 0.54% Met. Met supplementation increased the serum albumin, IgM, and total glutathione concentrations of 14-day-old chicks. In contrast, the serum alkaline phosphatase activity and hydroxyl radical concentration tended to decrease with increasing Met supplementation. In addition, the highest serum concentrations of IL-10, T-SOD, and GSH-PX were in the 0.54% Met-fed group. At 42 d of age, the serum ALB, IL-10, T-SOD, GSH-PX, T-AOC, and T-GSH were correlated with dietary Met levels. Finally, Met supplementation reduced the serum concentrations of ALP, IL-1β, IgA, IgG, hydrogen peroxide, and hydroxyl radicals. Thus, the inclusion of 0.43% or 0.54% Met in the diet helps chicks achieve superior performance during the brooding period and subsequently. In conclusion, Met doses of 0.43 to 0.54% could enhance the growth performance, protein utilization efficiency, antioxidant capacity, and immune responses of layer chicks, and to promote more desirable subsequent development during the brooding period.
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Affiliation(s)
- Jiatu Zhang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; Feed Safety and Healthy Livestock, Beijing Jingwa Agricultural Innovation Center, Beijing 101206, China
| | - Shunju Geng
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Yahao Zhu
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Lan Li
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Lihong Zhao
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; Feed Safety and Healthy Livestock, Beijing Jingwa Agricultural Innovation Center, Beijing 101206, China
| | - Qiugang Ma
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; Feed Safety and Healthy Livestock, Beijing Jingwa Agricultural Innovation Center, Beijing 101206, China
| | - Shimeng Huang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; Feed Safety and Healthy Livestock, Beijing Jingwa Agricultural Innovation Center, Beijing 101206, China.
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