Oropeza A, Wrenzycki C, Herrmann D, Hadeler K-G, Niemann H
Department of Biotechnology, Institute for Animal Breeding (FAL), Mariensee, 31535 Neustadt, Germany.
Biol Reprod. 2004 Jun;70(6):1634-43. doi: 10.1095/biolreprod.103.025494. Epub 2004 Feb 6.
The developmental potential of oocytes from prepubertal cattle is decreased, compared with those from their adult counterparts. The aim of the present study was to improve the developmental capacity of oocytes from prepubertal cattle by either systemic application of recombinant bovine somatotropin (rbST) or intraovarian injection of insulin-like growth factor-I (IGF-I). Blastocyst yields and the mRNA expression pattern (relative abundance, RA) of three putative marker genes (i.e., glucose transporter-1, Glut-1; eukaryotic translation initiation factor-1A, eIF1A, and upstream binding factor, UBF) were selected as criteria to determine the success of the treatments. At 6-7 mo of age, 30 healthy Holstein calves were randomly assigned to three experimental groups. The first group served as control and received an intraovarian injection of 0.6 ml acetic acid. The second group received a single s.c. injection of 500 mg of rbST. The third group received an intraovarian injection of 6 microg recombinant human IGF-I. During the following 2 wk, follicles were aspirated four times via transvaginal ultrasound-guided technology. All animals were i.m. injected with 60 mg FSH 48 h prior to each aspiration. The treatments were repeated with the same animals at 9-10, 11-12, and 14-15 mo of age. For comparison, five adult cows were each i.m. injected with 100 mg FSH and underwent oocyte retrieval. The proportion of oocytes considered to be developmentally competent was higher in cows than calves (65% vs. 58%, 50%, 52%) for the control, rbST, and IGF-I groups, respectively. The rate of blastocysts was similar in IGF-I-treated calves and cows (28% and 25%) and was higher (P </= 0.05) than in the controls and the rbST group (11% and 16%). The RA for Glut-1 was lower (P </= 0.05) in two- to four- cell embryos from calves, compared with cows. At the 8- to 16- cell stage, Glut-1 RA was similar in IGF-I-treated calves and cows. The RA for eIF1A was higher (P </= 0.05) in 8- to 16-cell embryos derived from cows than those from the control group. Results show that IGF-I intraovarian injection increased blastocyst yields and mRNA expression of Glut-1 and eIF1A to levels found in embryos produced from adult cows. This treatment may at least partially overcome the developmental deficiency of oocytes derived from calves and could be a step forward toward the use of prepubertal animals in breeding programs aimed at shortening the generation interval.
与成年牛的卵母细胞相比，青春期前牛的卵母细胞发育潜力较低。本研究的目的是通过全身应用重组牛生长激素（rbST）或卵巢内注射胰岛素样生长因子-I（IGF-I）来提高青春期前牛卵母细胞的发育能力。选择囊胚产量和三个假定标记基因（即葡萄糖转运蛋白-1，Glut-1；真核翻译起始因子-1A，eIF1A，和上游结合因子，UBF）的mRNA表达模式（相对丰度，RA）作为判断治疗是否成功的标准。在6-7月龄时，将30头健康的荷斯坦犊牛随机分为三个实验组。第一组作为对照组，接受0.6 ml乙酸的卵巢内注射。第二组接受单次皮下注射500 mg rbST。第三组接受6 μg重组人IGF-I的卵巢内注射。在接下来的2周内，通过经阴道超声引导技术对卵泡进行4次抽吸。每次抽吸前48 h，所有动物均肌肉注射60 mg促卵泡素（FSH）。在9-10、11-12和14-15月龄时，对同一批动物重复进行治疗。为作比较，对5头成年母牛分别肌肉注射100 mg FSH并进行卵母细胞采集。对照组、rbST组和IGF-I组中，被认为具有发育能力的卵母细胞比例在母牛中高于犊牛（分别为65%对58%、50%、52%）。IGF-I处理的犊牛和母牛的囊胚率相似（分别为28%和25%），且高于对照组和rbST组（分别为11%和16%，P≤0.05）。与母牛相比，犊牛二至四细胞胚胎中Glut-1的RA较低（P≤0.05）。在8至16细胞阶段，IGF-I处理的犊牛和母牛中Glut-1的RA相似。母牛来源的8至16细胞胚胎中eIF1A的RA高于对照组（P≤0.05）。结果表明，卵巢内注射IGF-I可提高囊胚产量，并使Glut-1和eIF1A的mRNA表达水平达到成年母牛所产胚胎中的水平。这种处理方法可能至少部分克服犊牛来源卵母细胞的发育缺陷，并且可能朝着在育种计划中使用青春期前动物以缩短世代间隔迈出了一步。
