The objective of this study was to determine the effects of bovine nerve growth factor-β (NGF) on pre-ovulatory follicle vascular area, LH release, ovulation, and luteal function when administered systemically to heifers. Post-pubertal Holstein heifers (n = 12) received an intravaginal progesterone-releasing device (CIDR) and GnRH agonist (100 μg IM). The CIDR was removed 5 d later, and heifers were given dinoprost (25 mg IM) at CIDR removal and 24 h later, followed by a second dose of GnRH agonist 48 h later. Heifers were randomly assigned to treatments using a cross-over design. For example, heifers assigned to NGF (250 μg reconstituted in 12 mL PBS IM) in replicate 1 were assigned to control (12 mL PBS IM) in replicate 2. Transrectal ultrasonography was performed before treatment and repeated every 4 h up to 32 h to determine the pre-ovulatory follicle diameter, vascular area, and ovulation. Serum samples were obtained to assess LH concentrations during the periovulatory period and every 2 d post-ovulation for measuring progesterone concentrations. A subset of heifers had luteal biopsies performed on days 9 (n = 6 per treatment) and 14 (n = 6 per treatment) post-ovulation to count luteal cell numbers and measure relative mRNA abundance for steroidogenic and angiogenic enzymes and LH receptor. Treatment with NGF increased pre-ovulatory follicle diameter (P = 0.02) and serum LH concentrations (P = 0.03) but did not affect time to ovulation (P = 0.42). Heifers treated with NGF had increased serum progesterone concentrations in the subsequent luteal phase (P = 0.03), but no change in vascular area of the follicle (P = 0.16) or CL (P = 0.20). Heifers treated with NGF had a greater number of small luteal cells (P < 0.01) and a tendency for increased LH receptor (LHR) mRNA abundance in the CL (P = 0.10). There was also increased steroidogenic acute regulatory protein (STAR; P = 0.05) and a tendency for increased cytochrome P450 family 11 (CYP11A1; P = 0.10) mRNA abundance in the CL of NGF-treated heifers. There was decreased prostaglandin E2 synthase (PGES; P = 0.03) and its receptor (PGER; P = 0.05) mRNA abundance and a tendency for decreased cytochrome P450 family 17 subfamily A member 1 (CYP17A1; P = 0.08) and hydroxysteroid 17-beta dehydrogenase (HSD17B; P = 0.06) mRNA abundance in the CL of NGF-treated heifers. Administration of NGF improved CL function in heifers potentially as a result of increased LH release.

中文翻译：

---

对具有排卵前卵泡的小母牛施用神经生长因子-β 可增强黄体形成和功能并促进 LH 释放

本研究的目的是确定牛神经生长因子-β (NGF) 对小母牛全身给药时对排卵前卵泡血管面积、LH 释放、排卵和黄体功能的影响。青春期后的荷斯坦小母牛（n = 12）接受了阴道内孕酮释放装置（CIDR）和 GnRH 激动剂（100 μg IM）。5 天后去除 CIDR，并在去除 CIDR 时和 24 小时后给予小母牛地诺前列素（25 mg IM），然后在 48 小时后给予第二剂 GnRH 激动剂。使用交叉设计将小母牛随机分配到治疗组。例如，在重复 1 中分配给 NGF（250 μg 在 12 mL PBS IM 中重构）的小母牛在重复 2 中分配给对照（12 mL PBS IM）。在治疗前进行经直肠超声检查，每 4 小时重复一次，直至 32 小时，以确定排卵前卵泡直径、血管面积和排卵。获取血清样本以评估排卵期期间和排卵后每 2 天的 LH 浓度，以测量孕酮浓度。一部分小母牛在排卵后第 9 天（每次治疗 n = 6）和第 14 天（每次治疗 n = 6）进行黄体活检，以计算黄体细胞数量并测量类固醇生成酶和血管生成酶以及 LH 受体的相对 mRNA 丰度。NGF 治疗增加了排卵前卵泡直径 (P = 0.02) 和血清 LH 浓度 (P = 0.03)，但不影响排卵时间 (P = 0.42)。用 NGF 处理的小母牛在随后的黄体期血清黄体酮浓度增加（P = 0.03），但毛囊血管面积 (P = 0.16) 或 CL (P = 0.20) 没有变化。用 NGF 处理的小母牛有更多数量的小黄体细胞 (P < 0.01) 和增加 CL 中 LH 受体 (LHR) mRNA 丰度的趋势 (P = 0.10)。在 NGF 处理的小母牛的 CL 中，类固醇生成急性调节蛋白 (STAR; P = 0.05) 和细胞色素 P450 家族 11 (CYP11A1; P = 0.10) mRNA 丰度也有增加的趋势。前列腺素 E2 合酶 (PGES; P = 0.03) 及其受体 (PGER; P = 0.05) mRNA 丰度降低，细胞色素 P450 家族 17 亚家族 A 成员 1 (CYP17A1; P = 0.08) 和羟基类固醇 17-β 有降低的趋势脱氢酶（HSD17B；P = 0.06）在 NGF 处理的小母牛 CL 中的 mRNA 丰度。