Colorado State University, Animal Reproduction and Biotechnology Laboratory, Fort Collins, Colorado, USA.
Theriogenology. 2012 Sep 1;78(4):830-41. doi: 10.1016/j.theriogenology.2012.03.033. Epub 2012 Apr 26.
Gonadotropin-releasing hormone is intermittently released from the hypothalamus in consistent patterns from before birth to final maturation of the hypothalamic-pituitary-gonadal axis at puberty. Disruption of this signaling via GnRH vaccination during the neonatal period can alter reproduction at maturity. The objective of this study was to investigate the long-term effects of GnRH-antibody exposure on reproductive maturation and function in elk calves passively exposed to high concentrations of GnRH antibodies immediately after birth. Fifteen elk calves (eight males and seven females) born to females treated with GnRH vaccine or sham vaccine during midgestation were divided into two groups based on the concentration of serum GnRH antibodies measured during the neonatal period. Those with robust (>15 pmol (125)I-GnRH bound per mL of serum) titers (N = 10; four females and six males) were designated as the exposed group, whereas those with undetectable titers (N = 5; three females and two males) were the unexposed group. Onset of puberty, reproductive development, and endocrine function in antibody-exposed and unexposed male and female elk calves were compared. Neonatal exposure to high concentrations of GnRH antibodies had no effect on body weight (P = 0.968), endocrine profiles (P > 0.05), or gametogenesis in either sex. Likewise, there were no differences between groups in gross or histologic structure of the hypothalamus, pituitary, testes, or ovaries. Pituitary stimulation with a GnRH analog before the second potential reproductive season induced substantial LH secretion in all experimental elk. All females became pregnant during their second reproductive season and all males exhibited similar mature secondary sexual characteristics. There were no differences between exposure groups in hypothalamic GnRH content (P = 0.979), pituitary gonadotropin content (P > 0.05) or gonadal structure. We concluded that suppressing GnRH signaling through immunoneutralization during the neonatal period likely does not alter long-term reproductive function in this species.
促性腺激素释放激素在出生前到青春期下丘脑-垂体-性腺轴最终成熟期间以一致的模式间歇性地从下丘脑释放。在新生儿期通过 GnRH 疫苗接种破坏这种信号传导会改变成熟时的生殖。本研究的目的是研究 GnRH 抗体暴露对被动暴露于 GnRH 抗体高浓度的 elk 小牛在出生后立即新生期生殖成熟和功能的长期影响。在妊娠中期用 GnRH 疫苗或假疫苗处理的雌性所生的 15 头 elk 小牛（8 头雄性和 7 头雌性）根据新生期测量的血清 GnRH 抗体浓度分为两组。那些具有强（> 15 pmol（125）I-GnRH 结合每毫升血清）滴度的（N = 10；4 头雌性和 6 头雄性）被指定为暴露组，而那些检测不到滴度的（N = 5；3 头雌性和 2 头雄性）为未暴露组。比较抗体暴露和未暴露的雄性和雌性 elk 小牛的青春期开始、生殖发育和内分泌功能。新生期暴露于高浓度 GnRH 抗体对体重（P = 0.968）、内分泌谱（P > 0.05）或两性配子发生均无影响。同样，在两性的下丘脑、垂体、睾丸或卵巢的大体或组织学结构方面，各组之间也没有差异。在第二个潜在生殖季节前用 GnRH 类似物刺激垂体会引起所有实验 elk 大量 LH 分泌。所有雌性在第二个生殖季节都怀孕，所有雄性都表现出相似的成熟第二性征。在 GnRH 含量（P = 0.979）、垂体促性腺激素含量（P > 0.05）或性腺结构方面，暴露组之间没有差异。我们得出结论，在新生儿期通过免疫中和抑制 GnRH 信号传导不太可能改变该物种的长期生殖功能。
