The role of GnRH in Tibetan male sheep and goat reproduction

Abstract

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.

Protein profile analysis of Jilin white goose testicles at different stages of the laying cycle by DIA strategy

“…Remarkably, we noticed that these proteins were downregulated in the mTOR signaling in the ELC vs. PLC group, suggesting their involvement in goose male fertility and spermatozoa production at the critical stage of the laying cycle. Our findings also demonstrated that several other interesting pathways were enriched in testicles tissues of the Jilin white goose, including the MAPK [ 37 ], Notch [ 38 ], GnRH signaling pathways [ 39 ], and other pathways related to reproductive hormone secretion and metabolic, which suggests that goose male reproduction is regulated with multiple signaling pathways and proteins that were widely studied to be associated with reproduction. It is worth noting that the metabolic pathways in the KEGG enrichment were significantly enriched, which suggested that may are cellular differences in testicular tissue in Jilin white geese with high and low sperm motility, and many of the DEPs identified may play a function in controlling cell metabolism, thereby involving in the regulation of sperm motility in Jilin white geese.…”

GnRH-mediated suppression of S100A4 expression inhibits endometrial epithelial cell proliferation in sheep via GNAI2/MAPK signaling

“…In livestock, GnRH also plays a wide range of regulatory roles ( 36 ), but some factors are unknown. Five studies analyzed the use of a GnRH agonist versus a control.…”

“…Beckett and Lean reported that GnRH administration before 40 days after delivery may shorten the time to first estrus but was not associated with the final reproductive performance of the cow ( 39 ). A review described the current research on GnRH function in sheep reproduction and indicated that GnRH plays a role in many aspects of reproduction ( 36 ). However, there are no direct reports on whether GnRH can regulate embryo implantation or its mechanism.…”

Exploring pathogenesis and biomarkers through establishment of a rat model of male infertility with liver depression and kidney deficiency

“…T and E 2 are indispensable steroid hormones for maintaining normal male reproductive function, and their levels are closely related to spermatogenesis. Consequently, GnRH, FSH, LH, T, and E 2 collectively construct a complex regulatory network within the endocrine system, intimately intertwined with testicular reproductive function, collaboratively upholding male reproductive health [ 67 ]. Nevertheless, in cases of HPGA dysfunction, disruptions in reproductive hormones may emerge, triggering testicular insufficiency and hindering sperm production, development, and maturation, ultimately culminating in MI.…”