IGF-I and NGFβ enhance in vitro progressive motility and vitality of human spermatozoa

NGF, EPO, and IGF-1 in the Male Reproductive System

Several studies have demonstrated interesting results considering the implication of three growth factors (GFs), namely nerve growth factor (NGF), erythropoietin (EPO), and the insulin-like growth factor-I (IGF-1) in the physiology of male reproductive functions. This review provides insights into the effects of NGF, EPO, and IGF-1 on the male reproductive system, emphasizing mainly their effects on sperm motility and vitality. In the male reproductive system, the expression pattern of the NGF system varies according to the species and testicular development, playing a crucial role in morphogenesis and spermatogenesis. In humans, it seems that NGF positively affects sperm motility parameters and NGF supplementation in cryopreservation media improves post-thaw sperm motility. In animals, EPO is found in various male reproductive tissues, and in humans, the protein is present in seminal plasma and testicular germ cells. EPO receptors have been discovered in the plasma membrane of human spermatozoa, suggesting potential roles in sperm motility and vitality. In humans, IGF-1 is expressed mainly in Sertoli cells and is present in seminal plasma, contributing to cell development and the maturation of spermatozoa. IGF-1 seems to modulate sperm motility, and treatment with IGF-1 has a positive effect on sperm motility and vitality. Furthermore, lower levels of NGF or IGF-1 in seminal plasma are associated with infertility. Understanding the mechanisms of actions of these GFs in the male reproductive system may improve the outcome of sperm processing techniques.

Risk of Sperm Disorders and Impaired Fertility in Frozen-Thawed Bull Semen: A Genome-Wide Association Study

Cryopreservation is a widely used method of semen conservation in animal breeding programs. This process, however, can have a detrimental effect on sperm quality, especially in terms of its morphology. The resultant sperm disorders raise the risk of reduced sperm fertilizing ability, which poses a serious threat to the long-term efficacy of livestock reproduction and breeding. Understanding the genetic factors underlying these effects is critical for maintaining sperm quality during cryopreservation, and for animal fertility in general. In this regard, we performed a genome-wide association study to identify genomic regions associated with various cryopreservation sperm abnormalities in Holstein cattle, using single nucleotide polymorphism (SNP) markers via a high-density genotyping assay. Our analysis revealed a significant association of specific SNPs and candidate genes with absence of acrosomes, damaged cell necks and tails, as well as wrinkled acrosomes and decreased motility of cryopreserved sperm. As a result, we identified candidate genes such as POU6F2, LPCAT4, DPYD, SLC39A12 and CACNB2, as well as microRNAs (bta-mir-137 and bta-mir-2420) that may play a critical role in sperm morphology and disorders. These findings provide crucial information on the molecular mechanisms underlying acrosome integrity, motility, head abnormalities and damaged cell necks and tails of sperm after cryopreservation. Further studies with larger sample sizes, genome-wide coverage and functional validation are needed to explore causal variants in more detail, thereby elucidating the mechanisms mediating these effects. Overall, our results contribute to the understanding of genetic architecture in cryopreserved semen quality and disorders in bulls, laying the foundation for improved animal reproduction and breeding.

In vitro effects of plasma rich in growth factors on human teratozoospermic semen samples

There is a correlation between teratozoospermia and production of reactive oxygen species leading to poor assisted reproductive techniques outcomes. This study aimed to examine the effect of plasma-rich in growth factors (PRGF) on teratozoospermic samples. Twenty-five teratozoospermic samples were included in this study. After sperm preparation, it was divided into four groups, including 0 (control), 1, 5, and 10% PRGF. Sperm motility, viability (eosin-nigrosin staining), morphology (Papanicolaou staining), DNA fragmentation (sperm chromatin dispersion test), mitochondrial membrane potential (JC-1 staining by flow cytometry), and lipid peroxidation (measurement of malondialdehyde, MDA) were evaluated before and after 1 h of incubation with or without PRGF. Our results showed that after 1 h of incubation, the addition of 1% PRGF improved sperm progressive motility (47.72 ± 13.76%) compared to the control group (17.36 ± 8.50%) (p < 0.001). Also, 1% PRGF preserved the sperm's total motility (77.50 ± 13.28% vs. 65.63 ± 19.03%, for 1% PRGF and control, respectively) and viability after incubation. The rate of normal sperm morphology was the same between different groups. Higher mitochondrial membrane potential and lower DNA fragmentation were also observed in sperm treated with different concentrations of PRGF compared to the control group, but the differences were non-significant. The MDA levels were significantly decreased in PRGF-treated groups compared to the control group (0.99 ± 0.62, 0.95 ± 0.33, 0.95 ± 0.79, and 1.49 ± 0.27 for 1% PRGF, 5% PRGF, 10% PRGF and control, respectively). Based on our results, it seems that PRGF incubation can improve sperm parameters and especially decrease the level of malondialdehyde as an indicator of oxidative stress, which is one of the main problems of teratozoospermic samples.

Effects of Growth Hormone on Adult Human Gonads: Action on Reproduction and Sexual Function

Growth hormone (GH), which is commonly considered to be a promoter of growth and development, has direct and indirect effects on adult gonads that influence reproduction and sexual function of humans and nonhumans. GH receptors are expressed in adult gonads in some species including humans. For males, GH can improve the sensitivity of gonadotropins, contribute to testicular steroidogenesis, influence spermatogenesis possibly, and regulate erectile function. For females, GH can modulate ovarian steroidogenesis and ovarian angiogenesis, promote the development of ovarian cells, enhance the metabolism and proliferation of endometrial cells, and ameliorate female sexual function. Insulin-like growth factor-1 (IGF-1) is the main mediator of GH. In vivo, a number of the physiological effects of GH are mediated by GH-induced hepatic IGF-1 and local IGF-1. In this review, we highlight the roles of GH and IGF-1 in adult human gonads, clarify potential mechanisms, and explore the efficacy and the risk of GH supplementation in associated deficiency and assisted reproductive technologies. Besides, the effects of excess GH on adult human gonads are discussed as well.