Department of Animal, Dairy and Veterinary Science, Utah State University, 4815 Old Main Hill, Logan, UT, 84322, USA; Department of Human Nutrition, Food and Animal Sciences, University of Hawai`i at Mānoa, 1955 East-West Rd., Honolulu, HI, 96822, USA.
Department of Animal, Dairy and Veterinary Science, Utah State University, 4815 Old Main Hill, Logan, UT, 84322, USA; Department of Biology, Westminster College, 1840 South 1300 East, Salt Lake City, UT, 84105, USA.
Domest Anim Endocrinol. 2023 Jan;82:106773. doi: 10.1016/j.domaniend.2022.106773. Epub 2022 Oct 23.
The majority of beef cattle in the United States often receive at least one anabolic implant resulting in improved growth, feed efficiency, and environmental and economic sustainability. However, the physiological and molecular mechanisms through which anabolic implants increase skeletal muscle growth of beef cattle remain elusive. The objective of this study was to identify transcriptional changes occurring in skeletal muscle of steers receiving anabolic implants containing different steroid hormones. Forty-eight steers were stratified by weight into 1 of 4 (n = 12/treatment) implant treatment groups: (1) estradiol (ImpE2; 25.7 mg E2; Compudose, Elanco Animal Health, Greenfield, IN), (2) trenbolone acetate (ImpTBA; 200 mg TBA; Finaplix-H, Merck Animal Health, Madison, NJ), (3) combination (ImpETBA; 120 mg TBA + 24 mg E2; Revalor-S, Merck Animal Health), or (4) no implant (CON). Skeletal muscle biopsies were taken from the longissimus 2 and 10 d post-implantation. The mRNA abundance of 94 genes associated with skeletal muscle growth was examined. At 10 d post-implantation, steers receiving ImpETBA had greater (P = 0.02) myoblast differentiation factor 1 transcript abundance than CON. Citrate synthase abundance was increased (P = 0.04) in ImpETBA steers compared to CON steers. In ImpE2 steers 10 d post-implantation, muscle RING finger protein 1 decreased (P = 0.05) compared to CON steers, and forkhead box protein O4 decreased (P = 0.05) in ImpETBA steers compared to CON steers. Interleukin-6 abundance tended to be increased (P = 0.09) in ImpE2 steers compared to both ImpETBA and CON steers. Furthermore, interleukin-10 mRNA abundance tended to be increased (P = 0.06) in ImpTBA steers compared to ImpETBA steers. Leptin receptor abundance was reduced (P = 0.01) in both ImpE2 and ImpTBA steers when compared to CON steers. Abundance of phosphodiesterase 4B was increased (P = 0.04) in ImpTBA steers compared to CON steers 2 d post-implantation. Taken together, the results of this research demonstrate that estradiol increases skeletal muscle growth via pathways related to nutrient partitioning and mitochondria function, while trenbolone acetate improves steer skeletal muscle growth via pathways related to muscle growth.
美国大多数肉牛通常至少接受一次合成代谢植入物，从而提高生长速度、饲料效率以及环境和经济可持续性。然而，合成代谢植入物增加肉牛骨骼肌生长的生理和分子机制仍不清楚。本研究的目的是鉴定接受含有不同类固醇激素的合成代谢植入物的阉牛骨骼肌中发生的转录变化。48 头阉牛按体重分为 4 个（n=12/处理）植入处理组之一：（1）雌二醇（ImpE2；25.7 mg E2；Compudose，Elanco Animal Health，Greenfield，IN），（2）醋酸 trenbolone（ImpTBA；200 mg TBA；Finaplix-H，Merck Animal Health，Madison，NJ），（3）组合（ImpETBA；120 mg TBA+24 mg E2；Revalor-S，Merck Animal Health）或（4）无植入物（CON）。在植入后 2 和 10 天从背最长肌 2 和 10 天采集骨骼肌活检。检查了 94 个与骨骼肌生长相关的基因的 mRNA 丰度。在植入后 10 天，接受 ImpETBA 的阉牛的成肌分化因子 1 转录物丰度高于 CON（P=0.02）。与 CON 阉牛相比，ImpETBA 阉牛的柠檬酸合酶丰度增加（P=0.04）。在植入后 10 天的 ImpE2 阉牛中，肌肉 RING 指蛋白 1 减少（P=0.05）与 CON 阉牛相比，ImpETBA 阉牛中的叉头框蛋白 O4 减少（P=0.05）与 CON 阉牛相比。与 ImpETBA 和 CON 阉牛相比，白细胞介素 6 的丰度在 ImpE2 阉牛中趋于增加（P=0.09）。此外，与 ImpETBA 阉牛相比，白细胞介素 10 的 mRNA 丰度在 ImpTBA 阉牛中趋于增加（P=0.06）。与 CON 阉牛相比，瘦素受体的丰度在 ImpE2 和 ImpTBA 阉牛中降低（P=0.01）。植入后 2 天，ImpTBA 阉牛的磷酸二酯酶 4B 丰度增加（P=0.04）与 CON 阉牛相比。总之，这项研究的结果表明，雌二醇通过与营养分配和线粒体功能相关的途径增加骨骼肌生长，而醋酸 trenbolone 通过与肌肉生长相关的途径改善牛骨骼肌生长。
