School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, China.
Institute of Animal Science, Tibet Academy of Agricultural and Animal Husbandry Science, Lhasa, China.
Reprod Domest Anim. 2023 Sep;58(9):1179-1187. doi: 10.1111/rda.14432. Epub 2023 Jul 26.
The hypothalamic-pituitary-gonadal (HPG) axis connects the hypothalamus, pituitary gland, and gonads. The regulation of reproductive processes includes integrating various factors from structural functions and environmental conditions in the HPG axis, with the outcome indication of these processes being the pulsatile secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus. These factors include feed consumption and nutritional condition, sex steroids, season/photoperiod, pheromones, age, and stress. GnRH pulsatile secretion affects the pattern of gonadotropin secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which then regulates both endocrine function and gamete maturation in the gonads. This regulates gonadotropins and testosterone (T) production. There is evidence that in males, GnRH participates in a variety of host behavioural and physiological processes such as the release of reproductive hormones, progression of spermatogenesis and sperm function, aggressive behaviour, and physiological metabolism. GnRH activates receptors expressed on Leydig cells and Sertoli cells, respectively to stimulate T secretion and spermatogenesis in the testis. Photoperiod affects the reproductive system of the hypothalamic-pituitary axis via rhythmic diurnal melatonin secretion. Increased release of melatonin promotes sexual activity, GnRH production, LH stimulation, and T production. This induces testicular functions, spermatogenesis, and puberty. GnRH reduces the release of LH by the pituitary through the cascade effect and decreases plasma concentration of T. Gut microbiota maintain sex steroid homeostasis and may induce reduction in reproduction productivity. Recently, findings of kisspeptin-neurokinin-dynorphin neuronal network in the brain have resulted in fast advances in how GnRH secretion is controlled. Emerging studies have also indicated that other neuropeptide analogues could be used in control reproduction procedures in various goat and sheep breeds. The Tibetan male sheep and goats reproduce on a seasonal basis and have high reproductive performance. This is a review for the role of GnRH in Tibetan male sheep and goats reproduction. This is intended to enhance reproductive knowledge for understanding the key roles of GnRH relating to male reproductive efficiency of Tibetan sheep or goats.
下丘脑-垂体-性腺（HPG）轴连接下丘脑、垂体和性腺。生殖过程的调节包括整合 HPG 轴中结构功能和环境条件的各种因素，其结果表现为下丘脑促性腺激素释放激素（GnRH）的脉冲式分泌。这些因素包括饲料消耗和营养状况、性激素、季节/光周期、信息素、年龄和应激。GnRH 脉冲式分泌影响促卵泡激素（FSH）和促黄体生成素（LH）的促性腺激素分泌模式，进而调节性腺中的内分泌功能和配子成熟。这调节了促性腺激素和睾酮（T）的产生。有证据表明，在男性中，GnRH 参与了多种宿主行为和生理过程，如生殖激素的释放、精子发生和精子功能的进展、攻击性行为和生理代谢。GnRH 激活分别表达在睾丸间质细胞和支持细胞上的受体，以刺激 T 的分泌和精子发生。光周期通过昼夜节律性褪黑素分泌影响下丘脑-垂体轴的生殖系统。褪黑素释放增加促进了性行为、GnRH 产生、LH 刺激和 T 产生。这诱导了睾丸功能、精子发生和青春期。GnRH 通过级联效应减少垂体中 LH 的释放，并降低 T 的血浆浓度。肠道微生物群维持性激素的稳态，并可能导致生殖生产力下降。最近，在大脑中发现了 kisspeptin-神经激肽-强啡肽神经元网络，这使得 GnRH 分泌的控制机制有了快速进展。新兴的研究还表明，其他神经肽类似物可以用于控制各种山羊品种的繁殖程序。藏绵羊和山羊季节性繁殖，繁殖性能高。这是一篇关于 GnRH 在藏绵羊和山羊繁殖中的作用的综述。这旨在增强对 GnRH 与藏绵羊或山羊雄性生殖效率相关的关键作用的生殖知识。
