Hernandez-Medrano J H, Williams R W, Peters A R, Hannant D, Campbell B K, Webb R
Division of Animal Sciences, School of Biosciences, The University of Nottingham, Loughborough, LE12 5RD, UK.
Reprod Fertil Dev. 2012;24(7):973-82. doi: 10.1071/RD11210.
The aim of the present study was to investigate the effect of the neonatal immunisation of bull calves against a novel gonadotrophin-releasing hormone (GnRH) construct, comprised of GnRH coupled to the glycoprotein D subunit of the bovine herpes virus-1 (GnRH-BHV1 gD), on endocrine status, reproductive organ development and carcass quality. Eighteen bull calves received either GnRH construct (n=9) or saline (control; n=9) at 2, 6 and 13.5 weeks of age. Blood samples were taken to determine antibody titres against GnRH, FSH and testosterone (T) concentrations and LH pulse characteristics, with testicular circumference monitored monthly. Immunisation reduced LH pulse amplitude (P<0.05) and T concentrations (P<0.05), particularly at the peak in anti-GnRH titres after the second booster at 16 weeks of age (P<0.001), but not when titres fell. Despite antibody titres decreasing after 16 weeks, immunisation reduced testicular size between 16 to 57 weeks of age (P<0.05), provoking an 8-week delay in puberty onset, defined as testicular circumference ≥14 cm. In conclusion, neonatal immunisation induced a significant immune response against GnRH, provoking a temporary endocrine disturbance that had a long-term effect on testicular development, delaying the onset of puberty. These results support the hypothesis that a developmental window exists during testicular development, such that disturbance of the endocrine drive to the gonads during this period results in a longer-term impairment of gonadal function.
本研究的目的是调查新生公牛犊接种一种新型促性腺激素释放激素（GnRH）构建体（由与牛疱疹病毒1型糖蛋白D亚基偶联的GnRH组成，即GnRH - BHV1 gD）对内分泌状态、生殖器官发育和胴体品质的影响。18头公牛犊在2周、6周和13.5周龄时分别接种GnRH构建体（n = 9）或生理盐水（对照组；n = 9）。采集血样以测定抗GnRH抗体滴度、促卵泡生成素（FSH）和睾酮（T）浓度以及促黄体生成素（LH）脉冲特征，每月监测睾丸周长。免疫接种降低了LH脉冲幅度（P < 0.05）和T浓度（P < 0.05），尤其是在16周龄第二次加强免疫后抗GnRH滴度达到峰值时（P < 0.001），但在滴度下降时则没有这种情况。尽管16周后抗体滴度下降，但免疫接种使16至57周龄期间的睾丸大小减小（P < 0.05），使青春期开始延迟了8周，青春期定义为睾丸周长≥14厘米。总之，新生期免疫接种引发了针对GnRH的显著免疫反应，导致暂时的内分泌紊乱，对睾丸发育产生长期影响，延迟了青春期的开始。这些结果支持了这样一种假说，即在睾丸发育过程中存在一个发育窗口，在此期间性腺内分泌驱动的紊乱会导致性腺功能的长期损害。
