Approximately 90% of beef cattle on feed in the United States receive at least one anabolic implant, which results in increased growth, efficiency, and economic return to producers. However, the complete molecular mechanism through which anabolic implants function to improve skeletal muscle growth remains unknown. This study had 2 objectives: (1) determine the effect of polyamines and their precursors on proliferation rate in bovine satellite cells (BSC); and (2) understand whether trenbolone acetate (TBA), a testosterone analog, has an impact on the polyamine biosynthetic pathway. To address these, BSC were isolated from 3 finished steers and cultured. Once cultures reached 75% confluency, they were treated in 1% fetal bovine serum (FBS) and/or 10 nM TBA, 10 mM methionine (Met), 8 mM ornithine (Orn), 2 mM putrescine (Put), 1.5 mM spermidine (Spd), or 0.5 mM spermine (Spe). Initially, a range of physiologically relevant concentrations of Met, Orn, Put, Spd, and Spe were tested to determine experimental doses to implement the aforementioned experiments. One, 12, or 24 h after treatment, mRNA was isolated from cultures and abundance of paired box transcription factor 7 (Pax7), Sprouty 1 (Spry), mitogen-activated protein kinase-1 (Mapk), ornithine decarboxylase (Odc), and S adenosylmethionine (Amd1) were determined, and normalized to 18S. No treatment × time interactions were observed (P ≥ 0.05). Treatment with TBA, Met, Orn, Put, Spd, or Spe increased (P ≤ 0.05) BSC proliferation when compared with control cultures. Treatment of cultures with Orn or Met increased (P ≤ 0.01) expression of Odc 1 h after treatment when compared with control cultures. Abundance of Amd1 was increased (P < 0.01) 1 h after treatment in cultures treated with Spd or Spe when compared with 1% FBS controls. Cultures treated with TBA had increased (P < 0.01) abundance of Spry mRNA 12 h after treatment, as well as increased mRNA abundance of Mapk (P < 0.01) 12 h and 24 h after treatment when compared with 1% FBS control cultures. Treatment with Met increased (P < 0.01) mRNA abundance of Pax7 1 h after treatment as compared with 1% FBS controls. These results indicate that treatments of BSC cultures with polyamines and their precursors increase BSC proliferation rate, as well as abundance of mRNA involved in cell proliferation. In addition, treatment of BSC cultures with TBA, polyamines, or polyamine precursors impacts expression of genes related to the polyamine biosynthetic pathway and proliferation.

在美国，大约 90% 的饲料肉牛至少接受了一种合成代谢植入物，从而提高了生产者的生长、效率和经济回报。然而，合成代谢植入物改善骨骼肌生长的完整分子机制仍然未知。本研究有两个目的：（1）确定多胺及其前体对牛卫星细胞（BSC）增殖率的影响；(2) 了解睾酮类似物醋酸群勃龙 (TBA) 是否对多胺生物合成途径有影响。为了解决这些问题，从 3 头成品公牛中分离出 BSC 并进行培养。一旦培养物达到 75% 汇合，它们就在 1% 胎牛血清 (FBS) 和/或 10 nM TBA、10 mM 蛋氨酸 (Met)、8 mM 鸟氨酸 (Orn)、2 mM 腐胺 (Put)、1.5 mM 亚精胺中处理(速度), 或 0.5 mM 精胺 (Spe)。最初，测试了一系列生理相关浓度的 Met、Orn、Put、Spd 和 Spe，以确定实施上述实验的实验剂量。处理后 1、12 或 24 小时，从培养物中分离出 mRNA 和配对盒转录因子 7 的丰度。测定了 Pax7 )、Sprouty 1 ( Spry )、丝裂原活化蛋白激酶-1 ( Mapk )、鸟氨酸脱羧酶 ( Odc ) 和 S 腺苷甲硫氨酸 ( Amd1 )，并标准化为 18S。没有治疗×时间相互作用中观察到（P ≥0.05）。与对照培养物相比，用 TBA、Met、Orn、Put、Spd 或 Spe 处理增加了 ( P ≤ 0.05) BSC 增殖。与对照培养物相比，用 Orn 或 Met 处理培养物后 1 小时，Odc 的表达增加（P ≤ 0.01）。Amd1 的丰度增加（P< 0.01) 与 1% FBS 对照相比，用 Spd 或 Spe 处理的培养物处理后 1 小时。与 1% FBS 对照培养物相比，用 TBA 处理的培养物在处理 12 小时后Spry mRNA 的丰度增加（P < 0.01），以及处理后12 小时和 24 小时Mapk 的mRNA 丰度增加（P < 0.01）。用 Met 处理增加了 ( P < 0.01) Pax7 的mRNA 丰度与 1% FBS 对照相比，处理后 1 小时。这些结果表明，用多胺及其前体处理 BSC 培养物可提高 BSC 增殖率，以及参与细胞增殖的 mRNA 丰度。此外，用 TBA、多胺或多胺前体处理 BSC 培养物会影响与多胺生物合成途径和增殖相关的基因的表达。