Santos R L, Silva C M, Ribeiro A F, Vasconcelos A C, Pesquero J L, Coelho S G, Serakides R, Reis S R
Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Theriogenology. 1999 Apr 1;51(5):975-84. doi: 10.1016/s0093-691x(99)00043-6.
Bovine growth hormone has been used in dairy cattle to increase milk production,but it also increases the twin parturition rate. This effect is mediated by insulin-like growth factor-I (IGF-I), which prevents follicular atresia by hindering apoptosis of granulosa cells. The action of GH and IGF-I on testicular function remains unclear. The goal of this study, therefore, was to verify the effects of short-term administration of GH and induced IGF-I release on the number of testicular germ cells, testicular morphology, and apoptosis in the bovine testis. Twenty Zebu bulls were split into 2 groups. The bulls in Group 1 (n = 10) were treated with 2 subcutaneous injections of bovine GH (500 mg/bull) 7 d apart. Group 2 bulls (n = 10) received placebos under the same protocol. All of the bulls were slaughtered 14 d after the start of treatment. Fragments of the testis were collected, fixed in Bouin's solution, embedded in paraffin, and the sections stained with hematoxilin and eosin. The paraffin-embedded sections were also used for in situ detection of apoptotic cells. Blood samples were collected at slaughter to measure serum levels of IGF-I, FSH and LH. Neither the number of Stage I seminiferous epithelium germ cells and the morphometric parameters (tubular diameter, seminiferous epithelium height, and volumetric proportions of structural components) nor the blood levels of FSH and LH showed a significant difference between the 2 groups. However, the treated animals showed an increase in serum IGF-I (P<0.01). Apoptotic germ cells were detected in the testis of both groups, showing the same pattern and a stage-specific apoptosis pattern. Most of the labeled cells were spermatocytes. The localization of apoptotic germ cells did not differ between groups. These results suggest that short-term administration of GH does not affect bovine spermatogenesis in adult bulls.
牛生长激素已被用于奶牛以提高产奶量，但它也会提高双胎分娩率。这种效应是由胰岛素样生长因子-I（IGF-I）介导的，IGF-I通过阻碍颗粒细胞凋亡来防止卵泡闭锁。生长激素（GH）和IGF-I对睾丸功能的作用仍不清楚。因此，本研究的目的是验证短期给予GH和诱导IGF-I释放对牛睾丸生殖细胞数量、睾丸形态以及细胞凋亡的影响。将20头泽布公牛分为2组。第1组（n = 10）的公牛每隔7天皮下注射2次牛GH（500 mg/头）。第2组公牛（n = 10）按照相同方案接受安慰剂。在治疗开始后14天宰杀所有公牛。收集睾丸组织碎片，用Bouin氏液固定，石蜡包埋，切片用苏木精和伊红染色。石蜡包埋切片也用于原位检测凋亡细胞。在宰杀时采集血样以测量血清中IGF-I、促卵泡激素（FSH）和促黄体生成素（LH）的水平。两组之间，I期生精上皮生殖细胞数量、形态学参数（管径、生精上皮高度和结构成分的体积比例）以及FSH和LH的血水平均无显著差异。然而，治疗组动物血清IGF-I水平升高（P<0.01）。在两组动物的睾丸中均检测到凋亡生殖细胞，呈现相同的模式和阶段特异性凋亡模式。大多数标记细胞为精母细胞。两组之间凋亡生殖细胞的定位没有差异。这些结果表明，短期给予GH不影响成年公牛的精子发生。
